Patent Application
20230253034
One embodiment of the present invention relates to a semiconductor device and an electronic device.
Note that one embodiment of the present invention is not limited to the above technical field. The technical field of the invention disclosed in this specification and the like relates to an object, a driving method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Therefore, specific examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a power storage device, an imaging device, a memory device, a signal processing device, a processor, an electronic device, a system, a driving method thereof, a manufacturing method thereof, and a testing method thereof.
Integrated circuits that imitate the mechanism of the human brain are currently under active development. The integrated circuits incorporate electronic circuits as the brain mechanism and include circuits corresponding to “neurons” and “synapses” of the human brain. Such integrated circuits may therefore be called “neuromorphic”, “brain-morphic”, or “brain-inspired” circuits, for example. The integrated circuits have a non-von Neumann architecture and are expected to be able to perform parallel processing with extremely low power consumption as compared with a von Neumann architecture, in which power consumption increases with increasing processing speed.
An information processing model that imitates a biological neural network including “neurons” and “synapses” is called an artificial neural network (ANN). For example, Non-Patent Document 1 and Non-Patent Document 2 each disclose an arithmetic device including an artificial neural network constructed using an SRAM (Static Random Access Memory).
An artificial neural network performs calculations in which the connection strength (sometimes referred to as weight coefficient) of a synapse that connects two neurons is multiplied by a signal transmitted between the two neurons. In particular, in a hierarchical artificial neural network, the connection strength of synapses between a plurality of first neurons in a first layer and one of second neurons in a second layer and signals input from the plurality of first neurons in the first layer to the one of the second neurons in the second layer need to be multiplied and summed (i.e., need to be subjected to product-sum operation); for example, the number of connection strengths and the number of parameters indicating the signals are determined in accordance with the scale of the artificial neural network. The second neuron performs operation with an activation function by using the result of the product-sum operation of the connection strength of synapses and the signals output from the first neurons, and outputs the arithmetic operation result as a signal to a third neuron in a third layer. That is, in the artificial neural network, as the number of layers, the number of neurons, and the like increase, the number of circuits corresponding to the “neurons” and “synapses” also increases, which sometimes makes the amount of arithmetic operation enormous. Thus, in some cases, power consumption of the circuits is increased, and the amount of heat generated from the circuits is also increased.
There are a variety of artificial neural network models; an example of a model used for image analysis is a convolutional neural network (CNN). A convolutional neural network is a kind of neural network that achieves excellent performance in the field of image recognition, and the amount of arithmetic operation depends on the resolution of images, the size of filters, and the like. Specifically, for example, as the resolution of an image becomes higher, as the size of a filter becomes larger, or as the stride becomes smaller, the amount of arithmetic operation in a convolutional neural network increases; thus, the power consumption of the circuits might be increased.
As the number of circuits included in a chip increases, the power consumption increases and the amount of heat generated when a device is driven also increases. In particular, a larger amount of heat generation is more likely to affect the characteristics of circuit elements included in a chip; thus, a circuit constituting the chip preferably includes circuit elements that are less affected by temperature. In addition, variations in characteristics of transistors, current sources, or the like included in a chip lead to variations in arithmetic operation results.
An object of one embodiment of the present invention is to provide a semiconductor device and the like that perform product-sum operation and/or arithmetic operation with a function. Another object of one embodiment of the present invention is to provide a semiconductor device and the like that perform convolutional processing. Another object of one embodiment of the present invention is to provide a semiconductor device and the like intended for AI. Another object of one embodiment of the present invention is to provide a semiconductor device and the like intended for a DNN. Another object of one embodiment of the present invention is to provide a semiconductor device and the like with low power consumption. Another object of one embodiment of the present invention is to provide a semiconductor device and the like that are less affected by environmental temperature. Another object of one embodiment of the present invention is to provide a semiconductor device and the like that are less affected by variations in characteristics of transistors. Another object of one embodiment of the present invention is to provide a semiconductor device and the like that are less affected by variations in characteristics of current sources. Another object of one embodiment of the present invention is to provide a novel semiconductor device and the like.
Note that the objects of one embodiment of the present invention are not limited to the objects listed above. The objects listed above do not preclude the existence of other objects. Note that the other objects are objects that are not described in this section and will be described below. The objects that are not described in this section are derived from the description of the specification, the drawings, and the like and can be extracted as appropriate from the description by those skilled in the art. Note that one embodiment of the present invention is to achieve at least one of the objects listed above and the other objects. Note that one embodiment of the present invention does not necessarily achieve all the objects listed above and the other objects.
(1)
One embodiment of the present invention is a semiconductor device including a first circuit and a second circuit. The first circuit includes a first holding portion and a first driving transistor. The second circuit includes a second holding portion and a second driving transistor. The first circuit is electrically connected to a first input wiring, a second input wiring, a first wiring, and a second wiring. The second circuit is electrically connected to the first input wiring, the second input wiring, the first wiring, and the second wiring. The first holding portion has a function of holding a first potential corresponding to a first current flowing between a source and a drain of the first driving transistor from the first wiring. The second holding portion has a function of holding a second potential corresponding to a second current flowing between a source and a drain of the second driving transistor from the second wiring. The first circuit has a function of outputting the first current to the first wiring when a first-level potential is input to the first input wiring and a second-level potential is input to the second input wiring; a function of outputting the first current to the second wiring when the second-level potential is input to the first input wiring and the first-level potential is input to the second input wiring; and a function of not outputting the first current to the first wiring and the second wiring when the second-level potential is input to the first input wiring and the second-level potential is input to the second input wiring. The second circuit has a function of outputting the second current to the second wiring when the first-level potential is input to the first input wiring and the second-level potential is input to the second input wiring; a function of outputting the second current to the first wiring when the second-level potential is input to the first input wiring and the first-level potential is input to the second input wiring; and a function of not outputting the second current to the first wiring and the second wiring when the second-level potential is input to the first input wiring and the second-level potential is input to the second input wiring. A current amount of each of the first current and the second current corresponds to a filter value included in a filter used for convolutional processing. The first-level potential and the second-level potential that are input to the first input wiring and the second input wiring are determined in accordance with image data subjected to the convolutional processing.
(2)
Another embodiment of the present invention is a semiconductor device that includes a first circuit and a second circuit and differs from the above (1) in some components. The first circuit includes a first holding portion and a first driving transistor. The second circuit includes a second holding portion and a second driving transistor. The first circuit is electrically connected to a first input wiring, a second input wiring, a first wiring, and a second wiring. The second circuit is electrically connected to the first input wiring, the second input wiring, the first wiring, and the second wiring. The first holding portion has a function of holding a first potential corresponding to a first current flowing between a source and a drain of the first driving transistor from the first wiring. The second holding portion has a function of holding a second potential corresponding to a second current flowing between a source and a drain of the second driving transistor from the second wiring. The first driving transistor has a function of making the first current corresponding to the held first potential flow between the source and the drain of the first driving transistor. The second driving transistor has a function of making the second current corresponding to the held second potential flow between the source and the drain of the second driving transistor. The first circuit has a function of outputting the first current to the first wiring in a first period when a first-level potential is input to the first input wiring and a second-level potential is input to the second input wiring; a function of outputting the first current to the second wiring in the first period when the second-level potential is input to the first input wiring and the first-level potential is input to the second input wiring; and a function of not outputting the first current to the first wiring and the second wiring in the first period when the second-level potential is input to the first input wiring and the second-level potential is input to the second input wiring. The second circuit has a function of outputting the second current to the second wiring in the first period when the first-level potential is input to the first input wiring and the second-level potential is input to the second input wiring; a function of outputting the second current to the first wiring in the first period when the second-level potential is input to the first input wiring and the first-level potential is input to the second input wiring; and a function of not outputting the second current to the first wiring and the second wiring in the first period when the second-level potential is input to the first input wiring and the second-level potential is input to the second input wiring. A current amount of each of the first current and the second current corresponds to a filter value included in a filter used for convolutional processing. The first-level potential and the second-level potential that are input to the first input wiring and the second input wiring and the length of the first period are determined in accordance with image data subjected to the convolutional processing.
(3)
In one embodiment of the present invention, the first period may include a second period and a third period in the above structure (2). Specifically, the first input wiring has a function of supplying the first-level potential or the second-level potential to both the first circuit and the second circuit in the second period. The second input wiring has a function of supplying the first-level potential or the second-level potential to both the first circuit and the second circuit in the second period. The first input wiring has a function of supplying the first-level potential or the second-level potential to both the first circuit and the second circuit in the third period. The second input wiring has a function of outputting the first-level potential or the second-level potential to both the first circuit and the second circuit in the third period. Note that the length of the third period is preferably greater than or equal to 1.8 times and less than or equal to 2.2 times the length of the second period.
(4)
In one embodiment of the present invention according to any one of the above (1) to (3), the first circuit may include a first transistor, a second transistor, a third transistor, and a first capacitor, and the second circuit may include a fourth transistor, a fifth transistor, a sixth transistor, and a second capacitor. Specifically, the first holding portion includes the first transistor and the first capacitor, and the second holding portion includes the fourth transistor and the second capacitor. A first terminal of the first transistor is electrically connected to a first terminal of the first capacitor and a gate of the first driving transistor. A second terminal of the first transistor is electrically connected to the first wiring. A first terminal of the first driving transistor is electrically connected to a first terminal of the second transistor and a first terminal of the third transistor. A second terminal of the second transistor is electrically connected to the first wiring. A gate of the second transistor is electrically connected to the first input wiring. A second terminal of the third transistor is electrically connected to the second wiring. A gate of the third transistor is electrically connected to the second input wiring. A first terminal of the fourth transistor is electrically connected to a first terminal of the second capacitor and a gate of the second driving transistor. A second terminal of the fourth transistor is electrically connected to the second wiring. A first terminal of the second driving transistor is electrically connected to a first terminal of the fifth transistor and a first terminal of the sixth transistor. A second terminal of the fifth transistor is electrically connected to the second wiring. A gate of the fifth transistor is electrically connected to the first input wiring. A second terminal of the sixth transistor is electrically connected to the first wiring. A gate of the sixth transistor is electrically connected to the second input wiring.
(5)
In one embodiment of the present invention according to the above (4), the first circuit may include a seventh transistor and the second circuit may include an eighth transistor. Specifically, a first terminal of the seventh transistor is electrically connected to the first terminal of the first driving transistor, the first terminal of the second transistor, and the first terminal of the third transistor. A second terminal of the seventh transistor is electrically connected to one of the first terminal and the second terminal of the first transistor. A first terminal of the eighth transistor is electrically connected to the first terminal of the second driving transistor, the first terminal of the fifth transistor, and the first terminal of the sixth transistor. A second terminal of the eighth transistor is electrically connected to one of the first terminal and the second terminal of the fourth transistor. A gate of the first transistor is electrically connected to a gate of the fourth transistor, a gate of the seventh transistor, and a gate of the eighth transistor.
(6)
In one embodiment of the present invention according to any one of the above (1) to (3), the first circuit may include a first transistor, a second transistor, a third transistor, and a first capacitor, and the second circuit may include a fourth transistor, a fifth transistor, a sixth transistor, and a second capacitor. Specifically, the first holding portion includes the first transistor and the first capacitor, and the second holding portion includes the fourth transistor and the second capacitor. A first terminal of the first transistor is electrically connected to a first terminal of the first capacitor and a gate of the first driving transistor. A first terminal of the first driving transistor is electrically connected to a second terminal of the first transistor, a first terminal of the second transistor, and a first terminal of the third transistor. A second terminal of the second transistor is electrically connected to the first wiring. A gate of the second transistor is electrically connected to the first input wiring. A second terminal of the third transistor is electrically connected to the second wiring. A gate of the third transistor is electrically connected to the second input wiring. A first terminal of the fourth transistor is electrically connected to a first terminal of the second capacitor and a gate of the second driving transistor. A first terminal of the second driving transistor is electrically connected to a second terminal of the fourth transistor, a first terminal of the fifth transistor, and a first terminal of the sixth transistor. A second terminal of the fifth transistor is electrically connected to the second wiring. A gate of the fifth transistor is electrically connected to the first input wiring. A second terminal of the sixth transistor is electrically connected to the first wiring. A gate of the sixth transistor is electrically connected to the second input wiring.
(7)
In one embodiment of the present invention according to any one of the above (1) to (3), the first circuit may include a third holding portion and a third driving transistor, and the second circuit may include a fourth holding portion and a fourth driving transistor. Specifically, the first circuit is electrically connected to a third wiring, and the second circuit is electrically connected to the third wiring. The third holding portion has a function of holding a third potential corresponding to a third current flowing between a source and a drain of the third driving transistor from the first wiring. The fourth holding portion has a function of holding a fourth potential corresponding to a fourth current flowing between a source and a drain of the fourth driving transistor from the second wiring. The third driving transistor has a function of making the third current corresponding to the held third potential flow between the source and the drain of the third driving transistor. The fourth driving transistor has a function of making the fourth current corresponding to the held fourth potential flow between the source and the drain of the fourth driving transistor. The semiconductor device has a function of switching the first current flowing through one of the first wiring and the second wiring to the third current and switching the second current flowing through the other of the first wiring and the second wiring to the fourth current, in accordance with a signal input to the third wiring.
(8)
One embodiment of the present invention according to any one of the above (1) to (7) may include a third circuit, a fourth circuit, and a fifth circuit. The third circuit has a function of supplying the first current corresponding to the filter value, to the first circuit through the first wiring; and a function of supplying the second current corresponding to the filter value, to the second circuit through the second wiring. The fourth circuit has a function of inputting the first-level potential or the second-level potential to the first input wiring in accordance with the image data; and a function of inputting the first-level potential or the second-level potential to the second input wiring in accordance with the image data. The fifth circuit has a function of comparing currents flowing from the first wiring and the second wiring, and outputting a potential corresponding to a product of the filter value and the image data from an output terminal of the fifth circuit.
(9)
Another embodiment of the present invention is an electronic device including the semiconductor device according to any one of the above (1) to (8) and a housing. In the electronic device, image feature extraction may be performed by the convolutional processing.
Note that in this specification and the like, a semiconductor device refers to a device that utilizes semiconductor characteristics, and means a circuit including a semiconductor element (a transistor, a diode, a photodiode, or the like), a device including the circuit, and the like. The semiconductor device also means all devices that can function by utilizing semiconductor characteristics. For example, an integrated circuit, a chip including an integrated circuit, an electronic component including a chip in a package, and the like are examples of the semiconductor device. Moreover, a memory device, a display device, a light-emitting device, a lighting device, an electronic device, and the like themselves are semiconductor devices, or include semiconductor devices in some cases.
In the case where there is description “X and Y are connected” in this specification and the like, the case where X and Y are electrically connected, the case where X and Y are functionally connected, and the case where X and Y are directly connected are regarded as being disclosed in this specification and the like. Accordingly, without being limited to a predetermined connection relation, for example, a connection relation shown in drawings or texts, a connection relation other than one shown in drawings or texts is regarded as being disclosed in the drawings or the texts. Each of X and Y denotes an object (e.g., a device, an element, a circuit, a wiring, an electrode, a terminal, a conductive film, or a layer).
For example, in the case where X and Y are electrically connected, one or more elements that allow electrical connection between X and Y (e.g., a switch, a transistor, a capacitor, an inductor, a resistor, a diode, a display device, a light-emitting device, and a load) can be connected between X and Y. Note that a switch has a function of being controlled to be turned on or off. That is, the switch has a function of being in a conduction state (on state) or a non-conduction state (off state) to control whether current flows or not.
For example, in the case where X and Y are functionally connected, one or more circuits that allow functional connection between X and Y (e.g., a logic circuit (an inverter, a NAND circuit, or a NOR circuit); a signal converter circuit (a digital-to-analog converter circuit, an analog-to-digital converter circuit, a gamma correction circuit, or the like); a potential level converter circuit (a power supply circuit (a step-up circuit, a step-down circuit, or the like), a level shifter circuit for changing the potential level of a signal, or the like); a voltage source; a current source; a switching circuit; an amplifier circuit (a circuit that can increase signal amplitude, the amount of current, or the like, an operational amplifier, a differential amplifier circuit, a source follower circuit, a buffer circuit, or the like); a signal generation circuit; a memory circuit; or a control circuit) can be connected between X and Y. For instance, even if another circuit is provided between X and Y, X and Y are regarded as being functionally connected when a signal output from X is transmitted to Y.
Note that an explicit description “X and Y are electrically connected” includes the case where X and Y are electrically connected (i.e., the case where X and Y are connected with another element or another circuit provided therebetween) and the case where X and Y are directly connected (i.e., the case where X and Y are connected without another element or another circuit provided therebetween).
It can be expressed as, for example, “X, Y, and a source (or a first terminal or the like) and a drain (or a second terminal or the like) of a transistor are electrically connected to each other, and X, the source (or the first terminal or the like) of the transistor, the drain (or the second terminal or the like) of the transistor, and Y are electrically connected in this order”. Alternatively, it can be expressed as “a source (or a first terminal or the like) of a transistor is electrically connected to X; a drain (or a second terminal or the like) of the transistor is electrically connected to Y; and X, the source (or the first terminal or the like) of the transistor, the drain (or the second terminal or the like) of the transistor, and Y are electrically connected to each other in this order”. Alternatively, it can be expressed as “X is electrically connected to Y through a source (or a first terminal or the like) and a drain (or a second terminal or the like) of a transistor, and X, the source (or the first terminal or the like) of the transistor, the drain (or the second terminal or the like) of the transistor, and Y are provided in this connection order”. When the connection order in a circuit configuration is defined by an expression similar to the above examples, a source (or a first terminal or the like) and a drain (or a second terminal or the like) of a transistor can be distinguished from each other to specify the technical scope. Note that these expressions are examples and the expression is not limited to these expressions. Here, X and Y each denote an object (e.g., a device, an element, a circuit, a wiring, an electrode, a terminal, a conductive film, or a layer).
Even when independent components are electrically connected to each other in a circuit diagram, one component has functions of a plurality of components in some cases. For example, when part of a wiring also functions as an electrode, one conductive film has functions of both of the components that are a wiring and an electrode. Thus, electrical connection in this specification includes, in its category, such a case where one conductive film has functions of a plurality of components.
In this specification and the like, a “resistor” can be, for example, a circuit element or a wiring having a resistance value higher than 0Ω. Therefore, in this specification and the like, a “resistor” sometimes includes a wiring having a resistance value, a transistor in which current flows between its source and drain, a diode, and a coil. Thus, the term “resistor” can be sometimes replaced with the terms “resistance”, “load”, “region having a resistance value”, and the like; conversely, the terms “resistance”, “load”, and “region having a resistance value” can be sometimes replaced with the term “resistor” and the like. The resistance value can be, for example, preferably greater than or equal to 1 mΩ and less than or equal to 10Ω, further preferably greater than or equal to 5 mΩ and less than or equal to 5Ω, still further preferably greater than or equal to 10 mΩ and less than or equal to 152. As another example, the resistance value may be greater than or equal to 1Ω and less than or equal to 1×109Ω.
In this specification and the like, a “capacitor” can be, for example, a circuit element having an electrostatic capacitance higher than 0 F, a region of a wiring having an electrostatic capacitance value, parasitic capacitance, or gate capacitance of a transistor. Thus, in this specification and the like, the terms “capacitor”, “parasitic capacitance”, “gate capacitance”, and the like can be replaced with the term “capacitance” or the like in some cases. Conversely, the term “capacitance” can be replaced with the terms “capacitor”, “parasitic capacitance”, “gate capacitance”, and the like in some cases. The term “pair of electrodes” of “capacitor” can be replaced with “pair of conductors”, “pair of conductive regions”, “pair of regions”, and the like. Note that the electrostatic capacitance value can be greater than or equal to 0.05 fF and less than or equal to 10 pF, for example. As another example, the electrostatic capacitance value may be greater than or equal to 1 pF and less than or equal to 10 μF.
In this specification and the like, a transistor includes three terminals called a gate, a source, and a drain. The gate is a control terminal for controlling the conduction state of the transistor. Two terminals functioning as the source and the drain are input/output terminals of the transistor. One of the two input/output terminals serves as the source and the other serves as the drain on the basis of the conductivity type (n-channel type or p-channel type) of the transistor and the levels of potentials applied to the three terminals of the transistor. Therefore, the terms “source” and “drain” can be replaced with each other in this specification and the like. In this specification and the like, expressions “one of a source and a drain” (or a first electrode or a first terminal) and “the other of the source and the drain” (or a second electrode or a second terminal) are used in description of the connection relation of a transistor. Depending on the transistor structure, a transistor may include a back gate in addition to the above three terminals. In that case, in this specification and the like, one of the gate and the back gate of the transistor may be referred to as a first gate and the other of the gate and the back gate of the transistor may be referred to as a second gate. Moreover, the terms “gate” and “back gate” can be replaced with each other in one transistor in some cases. In the case where a transistor includes three or more gates, the gates may be referred to as a first gate, a second gate, and a third gate, for example, in this specification and the like.
The case where a single circuit element is illustrated in a circuit diagram may indicate a case where the circuit element includes a plurality of circuit elements. For example, the case where a single resistor is illustrated in a circuit diagram may indicate a case where two or more resistors are electrically connected to each other in series. As another example, the case where a single capacitor is illustrated in a circuit diagram may indicate a case where two or more capacitors are electrically connected to each other in parallel. As another example, the case where a single transistor is illustrated in a circuit diagram may indicate a case where two or more transistors are electrically connected to each other in series and their gates are electrically connected to each other. Similarly, as another example, the case where a single switch is illustrated in a circuit diagram may indicate a case where a switch includes two or more transistors which are electrically connected to each other in series and whose gates are electrically connected to each other.
In this specification and the like, a node can be referred to as a terminal, a wiring, an electrode, a conductive layer, a conductor, an impurity region, or the like depending on the circuit configuration, the device structure, or the like. Furthermore, a terminal, a wiring, or the like can be referred to as a node.
In this specification and the like, “voltage” and “potential” can be replaced with each other as appropriate. “Voltage” refers to a potential difference from a reference potential, and when the reference potential is a ground potential, for example, “voltage” can be replaced with “potential”. Note that the ground potential does not necessarily mean 0 V. Moreover, potentials are relative values, and a potential supplied to a wiring, a potential applied to a circuit and the like, and a potential output from a circuit and the like, for example, change with a change of the reference potential.
In this specification and the like, the term “high-level potential” or “low-level potential” does not mean a particular potential. For example, in the case where two wirings are both described as “functioning as a wiring for supplying a high-level potential”, the levels of the high-level potentials supplied from the wirings are not necessarily equal to each other. Similarly, in the case where two wirings are both described as “functioning as a wiring for supplying a low-level potential”, the levels of the low-level potentials supplied from the wirings are not necessarily equal to each other.
“Current” means a charge transfer (electrical conduction); for example, the description “electrical conduction of positively charged particles occurs” can be rephrased as “electrical conduction of negatively charged particles occurs in the opposite direction”. Therefore, unless otherwise specified, “current” in this specification and the like refers to a charge transfer (electrical conduction) accompanied by carrier movement. Examples of a carrier here include an electron, a hole, an anion, a cation, and a complex ion, and the type of carrier differs between current flow systems (e.g., a semiconductor, a metal, an electrolyte solution, and a vacuum). The “direction of a current” in a wiring or the like refers to the direction in which a carrier with a positive charge moves, and the amount of current is expressed as a positive value. In other words, the direction in which a carrier with a negative charge moves is opposite to the direction of a current, and the amount of current is expressed as a negative value. Thus, in the case where the polarity of current (or the direction of current) is not specified in this specification and the like, the description “current flows from element A to element B” can be rephrased as “current flows from element B to element A”, for example. The description “current is input to element A” can be rephrased as “current is output from element A”, for example.
Ordinal numbers such as “first”, “second”, and “third” in this specification and the like are used to avoid confusion among components. Thus, the terms do not limit the number of components. In addition, the terms do not limit the order of components. In this specification and the like, for example, a “first” component in one embodiment can be referred to as a “second” component in other embodiments or the scope of claims. As another example, a “first” component in one embodiment in this specification and the like can be omitted in other embodiments or the scope of claims.
In this specification and the like, the terms for describing positioning, such as “over” and “under”, are sometimes used for convenience to describe the positional relation between components with reference to drawings. The positional relation between components is changed as appropriate in accordance with the direction in which the components are described. Thus, the positional relation is not limited to the terms described in the specification and the like, and can be described with another term as appropriate depending on the situation. For example, the expression “an insulator positioned over (on) a top surface of a conductor” can be replaced with the expression “an insulator positioned under (on) a bottom surface of a conductor” when the direction of a drawing showing these components is rotated by 180°.
Furthermore, the terms such as “over” and “under” do not necessarily mean that a component is placed directly over or directly under and in direct contact with another component. For example, the expression “electrode B over insulating layer A” does not necessarily mean that the electrode B is formed on and in direct contact with the insulating layer A, and does not exclude the case where another component is provided between the insulating layer A and the electrode B.
In this specification and the like, the terms “film”, “layer”, and the like can be interchanged with each other depending on the situation. For example, the term “conductive layer” can be changed into the term “conductive film” in some cases. As another example, the term “insulating film” can be changed into the term “insulating layer” in some cases. Alternatively, the term “film”, “layer”, or the like is not used and can be interchanged with another term depending on the case or the situation. For example, the term “conductive layer” or “conductive film” can be changed into the term “conductor” in some cases. As another example, the term “insulating layer” or “insulating film” can be changed into the term “insulator” in some cases.
In this specification and the like, the term “electrode”, “wiring”, “terminal”, or the like does not limit the function of a component. For example, an “electrode” is used as part of a “wiring” in some cases, and vice versa. Furthermore, the term “electrode” or “wiring” can also mean the case where a plurality of “electrodes”, “wirings”, or the like are formed in an integrated manner, for example. For example, a “terminal” is used as part of a “wiring,” an “electrode,” or the like in some cases, and vice versa. Furthermore, the term “terminal” also includes the case where a plurality of “electrodes”, “wirings”, “terminals”, or the like are formed in an integrated manner, for example. Therefore, for example, an “electrode” can be part of a “wiring” or a “terminal”, and a “terminal” can be part of a “wiring” or an “electrode”. Moreover, the terms “electrode”, “wiring”, “terminal”, and the like are sometimes replaced with the term “region” or the like depending on the case.
In this specification and the like, the terms “wiring”, “signal line”, “power supply line”, and the like can be interchanged with each other depending on the case or the situation. For example, the term “wiring” can be changed into the term “signal line” in some cases. As another example, the term “wiring” can be changed into the term “power supply line” or the like in some cases. Conversely, the term “signal line”, “power supply line”, or the like can be changed into the term “wiring” in some cases. The term “power supply line” or the like can be changed into the term “signal line” or the like in some cases. Conversely, the term “signal line” or the like can be changed into the term “power supply line” or the like in some cases. The term “potential” that is applied to a wiring can be changed into the term “signal” or the like depending on the case or the situation. Conversely, the term “signal” or the like can be changed into the term “potential” in some cases.
In this specification and the like, an impurity in a semiconductor refers to, for example, an element other than a main component of a semiconductor layer. For example, an element with a concentration of lower than 0.1 atomic % is an impurity. When an impurity is contained, for example, the density of defect states in a semiconductor is increased, carrier mobility is decreased, or crystallinity is decreased in some cases. In the case where the semiconductor is an oxide semiconductor, examples of an impurity that changes characteristics of the semiconductor include Group 1 elements, Group 2 elements, Group 13 elements, Group 14 elements, Group 15 elements, and transition metals other than the main components; specific examples are hydrogen (contained also in water), lithium, sodium, silicon, boron, phosphorus, carbon, and nitrogen. Specifically, in the case where the semiconductor is a silicon layer, examples of an impurity that changes characteristics of the semiconductor include Group 1 elements, Group 2 elements, Group 13 elements, and Group 15 elements (except oxygen and hydrogen).
In this specification and the like, a switch has a function of being in a conduction state (on state) or a non-conduction state (off state) to determine whether current flows or not. Alternatively, a switch has a function of selecting and changing a current path. For example, an electrical switch or a mechanical switch can be used. That is, a switch can be any element capable of controlling current, and is not limited to a particular element.
Examples of an electrical switch include a transistor (e.g., a bipolar transistor and a MOS transistor), a diode (e.g., a PN diode, a PIN diode, a Schottky diode, a MIM (Metal Insulator Metal) diode, a MIS (Metal Insulator Semiconductor) diode, and a diode-connected transistor), and a logic circuit in which such elements are combined. Note that in the case of using a transistor as a switch, a “conduction state” of the transistor refers to a state where a source electrode and a drain electrode of the transistor can be regarded as being electrically short-circuited. Furthermore, a “non-conduction state” of the transistor refers to a state where the source electrode and the drain electrode of the transistor can be regarded as being electrically disconnected. Note that in the case where a transistor operates just as a switch, there is no particular limitation on the polarity (conductivity type) of the transistor.
An example of a mechanical switch is a switch formed using a MEMS (micro electro mechanical system) technology. Such a switch includes an electrode that can be moved mechanically, and operates by controlling conduction and non-conduction with movement of the electrode.
In this specification, “parallel” indicates a state where two straight lines are placed at an angle greater than or equal to −10° and less than or equal to 10°. Thus, the case where the angle is greater than or equal to −5° and less than or equal to 5° is also included. In addition, “approximately parallel” or “substantially parallel” indicates a state where two straight lines are placed at an angle greater than or equal to −30° and less than or equal to 30°. Moreover, “perpendicular” indicates a state where two straight lines are placed at an angle greater than or equal to 80° and less than or equal to 100°. Thus, the case where the angle is greater than or equal to 85° and less than or equal to 95° is also included. Furthermore, “approximately perpendicular” or “substantially perpendicular” indicates a state where two straight lines are placed at an angle greater than or equal to 60° and less than or equal to 120°.
One embodiment can provide a semiconductor device and the like that perform product-sum operation and/or arithmetic operation with a function. Another embodiment of the present invention can provide a semiconductor device and the like that perform convolutional processing. Another embodiment of the present invention can provide a semiconductor device and the like with low power consumption. Another embodiment of the present invention can provide a semiconductor device and the like that are less affected by environmental temperature. Another embodiment of the present invention can provide a semiconductor device and the like that are less affected by variations in characteristics of transistors. Another embodiment of the present invention can provide a semiconductor device and the like that are less affected by variations in characteristics of current sources. Another embodiment of the present invention can provide a novel semiconductor device and the like.
Note that the effects of one embodiment of the present invention are not limited to the effects listed above. The effects listed above do not preclude the existence of other effects. Note that the other effects are effects that are not described in this section and will be described below. The effects that are not described in this section are derived from the description of the specification, the drawings, and the like and can be extracted from the description by those skilled in the art. Note that one embodiment of the present invention has at least one of the effects listed above and the other effects. Accordingly, depending on the case, one embodiment of the present invention does not have the effects listed above in some cases.
In an artificial neural network (hereinafter referred to as a neural network), the connection strength between synapses can be changed when existing information is given to the neural network. The processing for determining a connection strength by providing a neural network with existing information in such a manner is called “learning” in some cases.
Furthermore, when a neural network in which “learning” has been performed (the connection strength has been determined) is provided with some type of information, new information can be output on the basis of the connection strength. The processing for outputting new information on the basis of provided information and the connection strength in a neural network in such a manner is called “inference” or “recognition” in some cases.
Examples of the model of a neural network include a Hopfield type and a hierarchical type. In particular, a neural network with a multilayer structure is called a “deep neural network” (DNN) and machine learning using a deep neural network is called “deep learning” in some cases.
In this specification and the like, a metal oxide is an oxide of metal in a broad sense. Metal oxides are classified into an oxide insulator, an oxide conductor (including a transparent oxide conductor), an oxide semiconductor (also simply referred to as an OS), and the like. For example, in the case where a metal oxide is included in a channel formation region of a transistor, the metal oxide is referred to as an oxide semiconductor in some cases. That is, when a metal oxide can form a channel formation region of a transistor that has at least one of an amplifying function, a rectifying function, and a switching function, the metal oxide can be referred to as a metal oxide semiconductor. In the case where an OS transistor is mentioned, the OS transistor can also be referred to as a transistor including a metal oxide or an oxide semiconductor.
In this specification and the like, a metal oxide containing nitrogen is also collectively referred to as a metal oxide in some cases. A metal oxide containing nitrogen may be called a metal oxynitride.
In this specification and the like, one embodiment of the present invention can be constituted by appropriately combining a structure described in an embodiment with any of the structures described in the other embodiments. In addition, in the case where a plurality of structure examples are described in one embodiment, the structure examples can be combined as appropriate.
Note that a content (or part of the content) described in one embodiment can be applied to, combined with, or replaced with at least one of another content (or part of the content) in the embodiment and a content (or part of the content) described in one or a plurality of different embodiments.
Note that in each embodiment, a content described in the embodiment is a content described using a variety of diagrams or a content described with text disclosed in the specification.
Note that by combining a diagram (or part thereof) described in one embodiment with at least one of another part of the diagram, a different diagram (or part thereof) described in the embodiment, and a diagram (or part thereof) described in one or a plurality of different embodiments, much more diagrams can be formed.
Embodiments described in this specification are described with reference to the drawings. Note that the embodiments can be implemented in many different modes, and it will be readily appreciated by those skilled in the art that modes and details can be changed in various ways without departing from the spirit and scope thereof. Therefore, the present invention should not be interpreted as being limited to the description in the embodiments. Note that in the structures of the invention in the embodiments, the same portions or portions having similar functions are denoted by the same reference numerals in different drawings, and repeated description thereof is omitted in some cases. In perspective views and the like, some components might not be illustrated for clarity of the drawings.
In this specification and the like, when a plurality of components are denoted with the same reference numerals, and in particular need to be distinguished from each other, an identification sign such as “_1”, “[n]”, or “[m,n]” is sometimes added to the reference numerals. Components denoted with identification signs such as “_1”, “[n]”, and “[m,n]” in the drawings and the like are sometimes denoted without such identification signs in this specification and the like when the components do not need to be distinguished from each other.
In the drawings in this specification, the size, the layer thickness, or the region is exaggerated for clarity in some cases. Therefore, they are not limited to the illustrated scale. The drawings are schematic views showing ideal examples, and embodiments of the present invention are not limited to shapes, values, or the like shown in the drawings. For example, variations in signal, voltage, or current due to noise, variations in signal, voltage, or current due to difference in timing, or the like can be included.
This embodiment describes an arithmetic circuit that is a semiconductor device of one embodiment of the present invention and performs product-sum operation and/or arithmetic operation with a function.
First, a hierarchical neural network is described. A hierarchical neural network includes one input layer, one or a plurality of intermediate layers (hidden layers), and one output layer, for example, and is configured with a total of at least three layers. A hierarchical neural network 100 illustrated in
Each of the layers of the neural network 100 includes one or a plurality of neurons. In
Note that
Next, signal transmission from a neuron in one layer to a neuron in the subsequent layer and signals input to and output from the neurons are described. Note that description here is made focusing on the neuron Nj(k) in the k-th layer.
Specifically, z1(k-1) to zm(k-1) that are output signals from the neuron N1(k-1) to the neuron Nm(k-1) in the (k−1)-th layer are output to the neuron Nj(k). Then, the neuron Nj(k) generates zj(k) in accordance with z1(k-1) to zm(k-1), and outputs zj(k) as the output signal to the neurons in the (k+1)-th layer (not illustrated).
The efficiency of transmitting a signal input from a neuron in one layer to a neuron in the subsequent layer depends on the connection strength (hereinafter referred to as a weight coefficient) of the synapse that connects the neurons to each other. In the neural network 100, a signal output from a neuron in one layer is multiplied by the corresponding weight coefficient and then is input to a neuron in the subsequent layer. When i is an integer greater than or equal to 1 and less than or equal to m and the weight coefficient of the synapse between the neuron Ni(k-1) in the (k−1)-th layer and the neuron Nj(k) in the k-th layer is wi(k-1)j(k), a signal input to the neuron Nj(k) in the k-th layer can be expressed by Formula (1.1).
[Formula 1]
w
i
(k-1)
j
(k)
·z
i
(k-1) (1.1)
That is, when the signals are transmitted from the neuron N1(k-1) to the neuron Nm(k-1) in the (k−1)-th layer to the neuron Nj(k) in the k-th layer, the signals z1(k-1) to zm(k-1) are multiplied by the corresponding weight coefficients w1(k-1)j(k) to wm(k-1)j(k). Then, w1(k-1)j(k)·z1(k-1) to wm(k-1)j(k)·zm(k-1) are input to the neuron Nj(k) in the k-th layer. At this time, the total sum uj(k) of the signals input to the neuron Nj(k) in the k-th layer is expressed by Formula (1.2).
In addition, a bias may be added to the product-sum result of the weight coefficients w1(k-1)j(k) to wm(k-1)j(k) and the signals z1(k-1) to zm(k-1) of the neurons. When the bias is denoted by b, Formula (1.2) can be rewritten as the following formula.
The neuron Nj(k) generates the output signal zj(k) in accordance with uj(k). Here, the output signal zj(k) from the neuron Nj(k) is defined by the following formula.
z
j
(k)=ƒ(uj(k)) (1.4)
A function ƒ(uj(k)) is an activation function in a hierarchical neural network, and a step function, a ramp function (ReLU function), a sigmoid function, a tan h function, a softmax function, or the like can be used. Note that the activation function may be the same or different among all neurons. In addition, the neuron activation function may be the same or different between the layers.
Signals output from the neurons in the layers, the weight coefficients w, or the bias b may be an analog value or a digital value. For example, a binary or ternary digital value may be used. A value having a larger number of bits may be used. In the case of an analog value, for example, a linear ramp function, a sigmoid function, or the like is used as an activation function. In the case of a binary digital value, for example, a step function with an output of −1 or 1 or an output of 0 or 1 is used. Alternatively, the neurons in the layers may each output a ternary or higher-level signal; for example, as an activation function for outputting three levels, a step function with an output of −1, 0, or 1 or a step function with an output of 0, 1, or 2 is used, for example. Furthermore, as an activation function for outputting five levels, a step function with an output of −2, −1, 0, 1, or 2 may be used, for example. The use of a digital value as at least one of the signals output from the neurons in the layers, the weight coefficient w, and the bias b enables a reduction of the circuit scale, a reduction of power consumption, or an increase of arithmetic operation speed, for example. Furthermore, the use of an analog value as at least one of the signals output from the neurons in the layers, the weight coefficient w, and the bias b can improve the arithmetic operation accuracy.
The neural network 100 performs operation in which by input of an input signal to the first layer (the input layer), output signals are sequentially generated in the layers from the first layer (the input layer) to the last layer (the output layer) according to Formula (1.1), Formula (1.2) (or Formula (1.3)), and Formula (1.4) on the basis of the signals input from the previous layers, and the output signals are output to the subsequent layers. The signal output from the last layer (the output layer) corresponds to the calculation results of the neural network 100.
Described here is an example of an arithmetic circuit that is capable of performing the arithmetic operation of Formula (1.2) (or Formula (1.3)) and Formula (1.4) in the above-described neural network 100. Note that in the arithmetic circuit, for example, a weight coefficient of a synapse circuit of the neural network 100 has two levels (e.g., a combination of “−1” and “+1” or a combination of “0” and “+1”), three levels (e.g., a combination of “−1”, “0”, and “1”), or multiple levels of four or more levels (e.g., in the case of five levels, a combination of “−2”, “−1”, “0”, “1”, and “2”), and a neuron activation function is a function that outputs two levels (e.g., a combination of “−1” and “+1” or a combination of “0” and “+1”), three levels (e.g., a combination of “−1”, “0”, and “1”), or multiple levels of four or more levels (e.g., in the case of four levels, a combination of “0”, “1”, “2”, and “3”). In this specification and the like, one of a weight coefficient and a value of a signal (sometimes referred to as an arithmetic value) input from a neuron in one layer to a neuron in the subsequent layer is referred to as first data, and the other is referred to as second data in some cases. Note that the arithmetic value and the weight coefficient of the synapse circuit of the neural network 100 are not limited to digital values, and an analog value can be used as at least one of them.
An arithmetic circuit 110 illustrated in
Note that the whole or part of the arithmetic circuit 110 may be used for applications other than a neural network, AI, and the like. For example, in the case where product-sum operation processing, matrix operation processing, or the like is performed in calculation for graphics (e.g., convolutional processing for performing image feature extraction), scientific calculation, or the like, the processing may be performed using the whole or part of the arithmetic circuit 110. In other words, the whole or part of the arithmetic circuit 110 may be used for not only calculation for AI but also general calculation.
The circuit ILD is electrically connected to a wiring IL[1] to a wiring IL[n] and a wiring ILB[1] to a wiring ILB[n], for example. The circuit WLD is electrically connected to a wiring WLS[1] to a wiring WLS[m], for example. The circuit XLD is electrically connected to a wiring XLS[1] to a wiring XLS[m], for example. The circuit AFP is electrically connected to a wiring OL[1] to a wiring OL[n] and a wiring OLB[1] to a wiring OLB[n], for example.
The array portion ALP includes m×n circuits MP, for example. The circuits MP are arranged in a matrix of m rows and n columns in the array portion ALP, for example. Note that in
The circuit MP[i,j] is electrically connected to the wiring IL[j], the wiring ILB[j], the wiring WLS[i], the wiring XLS[i], the wiring OL[j], and the wiring OLB[j], for example.
The circuit MP[i,j] has a function of holding a weight coefficient between the neuron Ni(k-1) and the neuron Nj(k) (sometimes referred to as one of the first data and the second data, and here referred to as the first data), for example. Specifically, the circuit MP[i,j] holds information (e.g., a potential, a resistance value, or a current value) corresponding to the first data (a weight coefficient) input from the wiring IL[j] and the wiring ILB[j]. In addition, the circuit MP[i,j] has a function of outputting the product of a signal z1(k-1) output from the neuron Ni(k-1) (sometimes referred to as the other of the first data and the second data, and here referred to as the second data) and the first data. As a specific example, when the second data zi(k-1) is input from the wiring XLS[i], the circuit MP[i,j] outputs, to the wiring OL[j] and the wiring OLB[j], information (e.g., a current or a voltage) corresponding to the product of the first data and the second data or information (e.g., a current or a voltage) related to the product of the first data and the second data. Note that although an example of the case where the wiring IL[j] and the wiring ILB[1] are provided is described, one embodiment of the present invention is not limited thereto. Only one of the wiring IL[j] and the wiring ILB[1] may be provided.
The circuit ILD has a function of inputting, to the circuit MP[1,1] to the circuit MP[m,n], information (e.g., a potential, a resistance value, or a current value) corresponding to first data w1(k-1)l(k) to wm(k-1)n(k) that are weight coefficients, through the wiring IL[1] to the wiring IL[n] and the wiring ILB[1] to the wiring ILB[n], for example. As a specific example, the circuit ILD supplies, to the circuit MP[i,j], information (e.g., a potential, a resistance value, or a current value) corresponding to the first data wi(k-1)j(k) that is a weight coefficient, through the wiring IL[j] and the wiring ILB[j].
The circuit XLD has a function of supplying, to the circuit MP[1,1] to the circuit MP[m,n], the second data z1(k-1) to zm(k-1) corresponding to arithmetic values output from the neuron N1(k-1) to a neuron Nm(k-1), through the wiring XLS[1] to the wiring XLS[m], for example. Specifically, the circuit XLD supplies, to the circuit MP[i,1] to the circuit MP[i,n], information (e.g., a potential or a current value) corresponding to the second data zi(k-1) output from the neuron Ni(k-1), through the wiring XLS[i]. Although an example of the case where the wiring XLS[i] is provided is described, one embodiment of the present invention is not limited thereto. For example, in the arithmetic circuit 110 in
The circuit WLD has a function of selecting the circuit MP to which information (e.g., a potential, a resistance value, or a current value) corresponding to the first data input from the circuit ILD is to be written, for example. In the case where information (e.g., a potential, a resistance value, or a current value) is written to the circuit MP[i,1] to the circuit MP[i,n] positioned in the i-th row of the array portion ALP, for example, the circuit WLD supplies, to the wiring WLS[i], a signal for turning on or off writing switching elements included in the circuit MP[i,1] to the circuit MP[i,n], and supplies, to the other wirings WLS, a potential for turning off writing switching elements included in the circuits MP in rows other than the i-th row, for example. Although an example of the case where the wiring WLS[i] is provided is described, one embodiment of the present invention is not limited thereto. For example, in addition to the wiring WLS[i], a wiring transmitting an inverted signal of a signal input to the wiring WLS[i] may be additionally provided.
Although
The circuit AFP includes a circuit ACTF[1] to a circuit ACTF[n], for example. The circuit ACTF[j] is electrically connected to the wiring OL[j] and the wiring OLB[j], for example. The circuit ACTF[j] generates, for example, a signal corresponding to information (e.g., a potential or a current value) input from the wiring OL[j] and the wiring OLB[j]. For example, information input from the wiring OL[j] and information input from the wiring OLB[j] (e.g., potentials or current values) are compared and a signal based on the comparison result is generated. The signal corresponds to the signal zj(k) output from the neuron Nj(k). That is, the circuit ACTF[1] to the circuit ACTF[n] function as circuits that perform arithmetic operation of an activation function of the above-described neural network, for example. However, one embodiment of the present invention is not limited thereto. For example, the circuit ACTF[1] to the circuit ACTF[n] may have a function of converting an analog signal into a digital signal. As another example, the circuit ACTF[1] to the circuit ACTF[n] may have a function of amplifying an analog signal and outputting the amplified signal, i.e., a function of converting output impedance. As another example, the circuit ACTF[1] to the circuit ACTF[n] may have a function of converting a current or a charge into a voltage. As another example, the circuit ACTF[j] may have a function of initializing potentials of the wiring OL[j] and the wiring OLB[j].
Although the arithmetic circuit 110, the arithmetic circuit 120, and the arithmetic circuit 130 illustrated in
Next, the circuit ACTF[1] to the circuit ACTF[n] are described. The circuit ACTF[1] to the circuit ACTF[n] can have a circuit configuration shown in
In
The resistance values of the resistor RE and the resistor REB are preferably equal to each other. For example, the difference between the resistance values of the resistor RE and the resistor REB is desirably within 10%, further preferably within 5% of the resistance value of the resistor RE. However, one embodiment of the present invention is not limited thereto. Depending on the case or according to circumstances, the resistance values of the resistor RE and the resistor REB may be different values.
The wiring VAL functions as a wiring for supplying a constant voltage, for example. The constant voltage can be VDD that is a high-level potential, VSS that is a low-level potential, or a ground potential (GND), for example. The constant voltage is preferably set as appropriate in accordance with the configuration of the circuit MP. Alternatively, the wiring VAL may be supplied with not a constant voltage but a pulse signal, for example.
A voltage between the first terminal and the second terminal of the resistor RE is determined in accordance with a current flowing from the wiring OL[j]. Thus, a voltage based on the resistance value of the resistor RE and the current is input to the first input terminal of the comparator CMP. Similarly, a voltage between the first terminal and the second terminal of the resistor REB is determined in accordance with a current flowing from the wiring OLB[j]. Thus, a voltage based on the resistance value of the resistor REB and the current is input to the second input terminal of the comparator CMP.
The comparator CMP has a function of, for example, comparing voltages input to the first input terminal and the second input terminal and outputting a signal from an output terminal of the comparator CMP on the basis of the comparison result. For example, the comparator CMP can output a high-level potential from the output terminal of the comparator CMP in the case where the voltage input to the second input terminal is higher than the voltage input to the first input terminal, and can output a low-level potential from the output terminal of the comparator CMP in the case where the voltage input to the first input terminal is higher than the voltage input to the second input terminal. In other words, since a potential output from the output terminal of the comparator CMP is either a high-level potential or a low-level potential, the circuit ACTF[j] can output the binary output signal zj(k). For example, the high-level potential and the low-level potential output from the output terminal of the comparator CMP can correspond to “+1” and “−1” of the output signal zj(k), respectively. Depending on the case, the high-level potential and the low-level potential output from the output terminal of the comparator CMP may correspond to “+1” and “0” of the output signal zj(k), respectively.
Although the resistor RE and the resistor REB are used for the circuit ACTF[j] in
The comparator CMP included in each of the circuits ACTF[j] in
A switch S01a and a switch S01b may be provided in the circuit ACTF[j] in
The comparator CMP included in each of the circuits ACTF[j] in
A first terminal of the switch S02a is electrically connected to a terminal VinT, a first terminal of the switch S02b is electrically connected to a terminal VrefT, and a second terminal of the switch S02a is electrically connected to a second terminal of the switch S02b and a first terminal of the capacitor CC. A second terminal of the capacitor CC is electrically connected to an input terminal of the inverter circuit INV3 and a first terminal of the switch S03. A terminal VoutT is electrically connected to an output terminal of the inverter circuit INV3 and a second terminal of the switch S03.
The terminal VinT functions as a terminal for inputting an input potential to the comparator CMP, the terminal VrefT functions as a terminal for inputting a reference potential to the comparator CMP, and the terminal VoutT functions as a terminal for outputting an output potential from the comparator CMP. Note that the terminal VinT can correspond to one of the first terminal and the second terminal of each of the comparators CMP in
Although the circuits ACTF[j] in
The circuit ACTF[j] illustrated in
The wiring VrefL functions as a voltage line for supplying a constant voltage Vref, and Vref is preferably higher than or equal to GND and lower than or equal to VDD, for example. According to circumstances, Vref may be a potential lower than GND or a potential higher than VDD. Note that Vref is used as a reference potential (potential for comparison) in the comparator CMPa and the comparator CMPb.
A voltage between the first terminal and the second terminal of the resistor RE is determined in accordance with a current flowing from the wiring OL[j]. Thus, a voltage based on the resistance value of the resistor RE and the current is input to the first input terminal of the comparator CMPa. Similarly, a voltage between the first terminal and the second terminal of the resistor REB is determined in accordance with a current flowing from the wiring OLB[j]. Thus, a voltage based on the resistance value of the resistor REB and the current is input to the first input terminal of the comparator CMPb.
The comparator CMPa compares voltages input to the first input terminal and the second input terminal and outputs a signal from an output terminal of the comparator CMPa on the basis of the comparison result. For example, the comparator CMPa can output a high-level potential from the output terminal of the comparator CMPa in the case where the voltage (Vref) input to the second input terminal is higher than the voltage input to the first input terminal, and can output a low-level potential from the output terminal of the comparator CMPa in the case where the voltage input to the first input terminal is higher than the voltage (Vref) input to the second input terminal.
Like the comparator CMPa, the comparator CMPb compares voltages input to the first input terminal and the second input terminal and outputs a signal from an output terminal of the comparator CMPb on the basis of the comparison result. For example, the comparator CMPb can output a high-level potential from the output terminal of the comparator CMPb in the case where the voltage (Vref) input to the second input terminal is higher than the voltage input to the first input terminal, and can output a low-level potential from the output terminal of the comparator CMPb in the case where the voltage input to the first input terminal is higher than the voltage (Vref) input to the second input terminal.
At this time, the potentials output from the output terminals of the comparator CMPa and the comparator CMPb can each be expressed as the ternary output signal zj(k), for example. For example, the output signal zj(k) can be “+1” in the case where a high-level potential is output from the output terminal of the comparator CMPa and a low-level potential is output from the output terminal of the comparator CMPb; the output signal zj(k) can be “−1” in the case where a low-level potential is output from the output terminal of the comparator CMPa and a high-level potential is output from the output terminal of the comparator CMPb; and the output signal zj(k) can be “0” in the case where a low-level potential is output from the output terminal of the comparator CMPa and a low-level potential is output from the output terminal of the comparator CMPb.
The circuit configuration of the circuit ACTF[j] is not limited to that illustrated in
For example, the wiring VrefL electrically connected to the second input terminals of the comparator CMPa and the comparator CMPb in
As another example, as a component different from the circuits ACTF[j] in
The wiring OL[j] is electrically connected to the first terminal of the resistor RE and a non-inverting input terminal of the operational amplifier OPa, and the wiring OLB[j] is electrically connected to the first terminal of the resistor REB and a non-inverting input terminal of the operational amplifier OPb. An inverting input terminal of the operational amplifier OPa is electrically connected to an output terminal of the operational amplifier OPa, and an inverting input terminal of the operational amplifier OPb is electrically connected to an output terminal of the operational amplifier OPb. Furthermore, the second terminal of the resistor RE is electrically connected to the wiring VAL, and the second terminal of the resistor REB is electrically connected to the wiring VAL.
That is, the operational amplifier OPa and the operational amplifier OPb included in the circuit ACTF[j] in
As another example, as a component different from the circuits ACTF[j] in
The wiring OL[j] is electrically connected to a first input terminal (e.g., the inverting input terminal) of the operational amplifier OPa and a first terminal of the load LEa, and the wiring OLB[j] is electrically connected to a first input terminal (e.g., the inverting input terminal) of the operational amplifier OPb and a first terminal of the load LEb. Moreover, a second input terminal (e.g., the non-inverting input terminal) of the operational amplifier OPa is electrically connected to the wiring Vref1L, and a second input terminal (e.g., the non-inverting input terminal) of the operational amplifier OPb is electrically connected to the wiring Vref2L. A second terminal of the load LEa is electrically connected to the output terminal of the operational amplifier OPa, and a second terminal of the load LEb is electrically connected to the output terminal of the operational amplifier OPb.
Note that the wiring Vref1L and the wiring Vref2L function as wirings that supply voltages equal to or different from each other. Thus, the wiring Vref1L and the wiring Vref2L can be combined into one wiring in some cases.
The load LEa and the load LEb of the circuit ACTF[j] in
In the circuit ACTF[j] in
As another example, as a component different from the circuits ACTF[j] in
The wiring OL[j] is electrically connected to an input terminal of the analog-to-digital converter circuit ADCa and the first terminal of the resistor RE, and the wiring OLB[j] is electrically connected to an input terminal of the analog-to-digital converter circuit ADCb and the first terminal of the resistor REB. The second terminal of the resistor RE is electrically connected to the wiring VAL, and the second terminal of the resistor REB is electrically connected to the wiring VAL.
In the circuit ACTF[j] in
Note that as in
Although the arithmetic circuit 110, the arithmetic circuit 120, and the arithmetic circuit 130 illustrated in
The switching circuit TW[1] to the switching circuit TW[n] each include a terminal TSa, a terminal TSaB, a terminal TSb, a terminal TSbB, a terminal TSc, and a terminal TScB.
The terminal TSa is electrically connected to the wiring OL[j], the terminal TSb is electrically connected to the circuit ILD, and the terminal TSc is electrically connected to the circuit ACTF[j]. The terminal TSaB is electrically connected to the wiring OLB[j], the terminal TSbB is electrically connected to the circuit ILD, and the terminal TScB is electrically connected to the circuit ACTF[j].
The switching circuit TW[j] has a function of establishing electrical continuity between the terminal TSa and one of the terminal TSb and the terminal TSc, and breaking electrical continuity between the terminal TSa and the other of the terminal TSb and the terminal TSc. In addition, the switching circuit TW[j] has a function of establishing electrical continuity between the terminal TSaB and one of the terminal TSbB and the terminal TScB, and breaking electrical continuity between the terminal TSaB and the other of the terminal TSbB and the terminal TScB.
That is, in the case where information (e.g., a potential, a resistance value, or a current value) corresponding to the first data w1(k-1)l(k) to wm(k-1)n(k) that are weight coefficients is to be input to any one of the circuit MP[1,j] to the circuit MP[m,j], electrical continuity is established between the terminal TSa and the terminal TSb and electrical continuity is established between the terminal TSaB and the terminal TSbB in the switching circuit TW[j], whereby information (e.g., a potential, a resistance value, or a current value) corresponding to the first data w1(k-1)l(k) to wm(k-1)n(k) can be supplied from the circuit ILD to any one of the circuit MP[1,j] to the circuit MP[m,j] through the wiring OL[j] or the wiring OLB[j].
In the case where the circuit ACTF[j] needs to obtain the sum result of the products (Formula (1.2)) of the weight coefficients and the signals of neurons calculated by the circuit MP[1,j] to the circuit MP[m,j], electrical continuity is established between the terminal TSa and the terminal TSc and electrical continuity is established between the terminal TSaB and the terminal TScB in the switching circuit TW[j], whereby information (e.g., a potential, a resistance value, or a current value) corresponding to the product-sum result can be supplied from the wiring OL[j] and the wiring OLB[j] to the circuit ACTF[j]. Then, the value of the activation function is calculated from the input product-sum result in the circuit ACTF[j], whereby the signal zj(k) can be obtained as the output signal of the neuron.
Next, the switching circuit TW[j] and the circuit ILD that are included in the arithmetic circuit 140 are described.
The switching circuit TW[j] includes a switch SWI, a switch SWIB, a switch SWO, a switch SWOB, a switch SWL, a switch SWLB, a switch SWH, and a switch SWHB, for example.
The circuit ILD includes a current source circuit ISC, for example. However, one embodiment of the present invention is not limited thereto. For example, a voltage source circuit may be provided instead of the current source circuit ISC. The current source circuit ISC has a function of supplying, to the wiring OL[j] and/or the wiring OLB[j], a current corresponding to a weight coefficient (the first data) to be input to the circuit MP. Note that at least one current source circuit ISC as a circuit for the wiring OL[j] and at least one current source circuit ISC as a circuit for the wiring OLB[j] may be separately provided. Alternatively, as illustrated in
The current source circuit ISC includes one or a plurality of constant current sources; for example, a constant current source circuit ISC1, a constant current source circuit ISC2, and a constant current source circuit ISC3 are included as the plurality of constant current sources in
Note that currents flowing to the wiring OL[j] and the wiring OLB[j] are preferably generated in the same current source circuit ISC, as shown in
Note that as each of the switch SWI, the switch SWIB, the switch SWO, the switch SWOB, the switch SWL, the switch SWLB, the switch SWH, the switch SWHB, the switch SWC1, the switch SWC2, and the switch SWC3 illustrated in
In an example of the switching circuit TW[j], the terminal TSa is electrically connected to a first terminal of the switch SWI, a first terminal of the switch SWO, a first terminal of the switch SWL, and a first terminal of the switch SWH. The terminal TSaB is electrically connected to a first terminal of the switch SWIB, a first terminal of the switch SWOB, a first terminal of the switch SWLB, and a first terminal of the switch SWHB. A second terminal of the switch SWI is electrically connected to a terminal TSb1. A second terminal of the switch SWIB is electrically connected to a terminal TSbB1. A second terminal of the switch SWO is electrically connected to the terminal TSc. A second terminal of the switch SWOB is electrically connected to the terminal TScB. A second terminal of the switch SWL is electrically connected to a terminal TSb2. A second terminal of the switch SWLB is electrically connected to a terminal TSbB2. A second terminal of the switch SWH is electrically connected to a terminal TSb3. A second terminal of the switch SWHB is electrically connected to a terminal TSbB3.
The terminal TSb1, the terminal TSb2, and the terminal TSb3 illustrated in
In the current source circuit ISC included in the circuit ILD, the terminal TSb1 is electrically connected to a first terminal of the switch SWC1, a first terminal of the switch SWC2, and a first terminal of the switch SWC3. The terminal TSbB1 is electrically connected to the first terminal of the switch SWC1, the first terminal of the switch SWC2, and the first terminal of the switch SWC3. A second terminal of the switch SWC1 is electrically connected to an output terminal of the constant current source circuit ISC1, a second terminal of the switch SWC2 is electrically connected to an output terminal of the constant current source circuit ISC2, and a second terminal of the switch SWC3 is electrically connected to an output terminal of the constant current source circuit ISC3. An input terminal of the constant current source circuit ISC1, an input terminal of the constant current source circuit ISC2, and an input terminal of the constant current source circuit ISC3 are electrically connected to a wiring VSO.
The wiring VSO functions as a wiring for supplying a constant voltage to the constant current source circuit ISC1, the constant current source circuit ISC2, and the constant current source circuit ISC3. For example, in the case where a current is supplied from the circuit ILD to the wiring OL or the wiring OLB through the switching circuit TW[j], the constant voltage is preferably a potential higher than a ground potential (e.g., VDD), and it is further preferable to use the constant current source circuit ISC1 (the constant current source circuit ISC2 or the constant current source circuit ISC3) illustrated in
Other than the circuits in
Here, when a constant voltage supplied from the wiring VSO is a high-level potential, the high-level potential is input to the first terminal of the transistor illustrated in
Alternatively, in the case of
In this specification and the like, when the threshold voltage of the transistor is denoted as Vth, “around the boundary between the saturation region and the subthreshold region” includes the case where the gate-source voltage is higher than or equal to Vth−1.0 V, higher than or equal to Vth−0.5 V, or higher than or equal to Vth−0.1 V and lower than or equal to Vth+0.1 V, lower than or equal to Vth+0.5 V, or lower than or equal to Vth+1.0 V, for example. Note that any of the lower limits and the upper limits described above can be combined with each other.
The case of
When a current flowing from the constant current source circuit ISC1 has Iut, a current flowing from the constant current source circuit ISC2 preferably has 2Iut and a current flowing from the constant current source circuit ISC3 preferably has 4Iut, for example. That is, in the case where the current source circuit ISC includes P constant current sources (P is an integer greater than or equal to 1), a current flowing from the p-th constant current source (p is an integer greater than or equal to 1 and less than or equal to P) preferably has 2(p-1)×Iut. The amount of current flowing from the current source circuit ISC can be changed in this manner.
For example, the number of constant current sources in the current source circuit ISC is set to three (P=3). In the case where a current of ut is to flow to the wiring OL[j], the switch SWI is turned on and the switch SWIB is turned off, and then the switch SWC1 is turned on and the switch SWC2 and the switch SWC3 are turned off. In the case where a current of 5Iut is to flow to the wiring OL[j], the switch SWC1 and the switch SWC3 are turned on and the switch SWC2 is turned off. That is, the current source circuit ISC can output a current having any one of eight levels (“0”, “Iut”, “2Iut”, “3Iut”, “4Iut”, “5Iut”, “6Iut”, and “7Iut”). Note that in the case where a current with larger than eight levels is to be output, the number of constant current sources is set to four or more. Similarly, by turning off the switch SWI and turning on the switch SWIB, a current having any one of the eight levels can flow to the wiring OLB[j]. Note that in the case where the current source circuit ISC does not output a current, the switch SWI and the switch SWIB of the switching circuit TW may be turned off without turning off the switch SWC1 to the switch SWC3 of the current source circuit ISC. By providing a plurality of constant current sources in this manner, the current source circuit ISC can output a current amount corresponding to a control signal (a digital value) for switching the on state and the off state of each switch. In other words, the current source circuit ISC performs digital-to-analog (DA) conversion of the control signal into the current amount. Note that the current source circuit may be configured to freely change a current value output from the current source circuit as an analog value, and the circuit ILD may include only one current source circuit with that configuration.
Note that in the above example, a current flowing from the p-th constant current source has 2(p-1)×Iut in the case where the current source circuit ISC includes P constant current sources; however, one embodiment of the present invention is not limited thereto. For example, a current flowing from the constant current source circuit ISC1, a current flowing from the constant current source circuit ISC2, and a current flowing from the constant current source circuit ISC3 may all have the same amount. For example, in the case where the current output from the current source circuit ISC has eight levels, the amount of current output from the current source circuit ISC may be controlled in the following manner: the number of constant current sources in the current source circuit ISC is seven (P=7), currents from the constant current sources in the current source circuit ISC are all set to have the same amount, and how many current sources will output a current is controlled.
In the circuit ILD, the terminal TSb2 is electrically connected to the wiring VCN and the terminal TSbB2 is electrically connected to the wiring VCN.
The wiring VCN functions as a wiring for supplying a constant voltage to the wiring OL[j] and/or the wiring OLB[j]. In the case where a current (positive current) is supplied from the circuit ILD to the wiring OL or the wiring OLB through the switching circuit TW[j], for example, a constant voltage supplied from the wiring VCN is preferably a low-level potential (e.g., VSS). In the case where a current (negative current) is supplied from the wiring OL or the wiring OLB to the circuit ILD through the switching circuit TW[j], for example, a constant potential supplied from the wiring VCN is preferably a high-level potential. Note that in the case where a capacitor C3 is connected to a source terminal of a transistor M1 or the like and the source terminal is not connected to a power supply line or the like as illustrated in
In the circuit ILD, the terminal TSb3 is electrically connected to the wiring VCN2 and the terminal TSbB3 is electrically connected to the wiring VCN2.
The wiring VCN2 functions as a wiring for supplying a constant voltage to the wiring OL[j] and/or the wiring OLB[j]. In the case where a current (positive current) is supplied from the circuit ILD to the wiring OL or the wiring OLB through the switching circuit TW[j], for example, a constant voltage supplied from the wiring VCN is preferably a high-level potential (e.g., VDD). In the case where a current (negative current) is supplied from the wiring OL or the wiring OLB to the circuit ILD through the switching circuit TW[j], for example, a constant potential supplied from the wiring VCN is preferably a low-level potential.
By switching the on state and the off state of each of the switch SWI, the switch SWIB, the switch SWO, the switch SWOB, the switch SWL, the switch SWLB, the switch SWH, and the switch SWHB, the switching circuit TW[j] can change a circuit that establishes electrical continuity with the wiring OL[j] and the wiring OLB[j].
Here, a weight coefficient input to the circuit MP is described.
When a positive weight coefficient is to be input to the circuit MP, a current corresponding to the weight coefficient is input to the wiring OL[j] and a constant potential supplied from the wiring VCN is input to the wiring OLB[j]. For example, electrical continuity is established between the current source circuit ISC and the wiring OL[j], electrical continuity is not established between the current source circuit ISC and the wiring OLB[j], electrical continuity is not established between the circuit AFP and the wiring OL[j], electrical continuity is not established between the circuit AFP and the wiring OLB[j], electrical continuity is not established between the wiring VCN and the wiring OL[j], electrical continuity is established between the wiring VCN and the wiring OLB[j], electrical continuity is not established between the wiring VCN2 and the wiring OL[j], and electrical continuity is not established between the wiring VCN2 and the wiring OLB[j]. That is, in the switching circuit TW[j], the switches SWI and SWLB are turned on, and the switch SWIB, the switch SWO, the switch SWOB, the switch SWL, the switch SWH, and the switch SWHB are turned off. Accordingly, electrical continuity is established between the current source circuit ISC and the wiring OL[j], so that a current can flow from the current source circuit ISC to the circuit MP through the wiring OL[j]. When the number of constant current sources in the current source circuit ISC is P, the current has any one of 2P−1 levels (zero current is not included). Since the positive weight coefficient input to the circuit MP is determined in accordance with the current, the weight coefficient can have any one of 2P−1 values. In addition, electrical continuity is established between the wiring VCN and the wiring OLB[j], so that a constant voltage is input from the wiring VCN to the wiring OLB[j].
When a negative weight coefficient is to be input to the circuit MP, a current corresponding to the weight coefficient is input to the wiring OLB[j] and a constant potential supplied from the wiring VCN is input to the wiring OL[j]. For example, electrical continuity is not established between the current source circuit ISC and the wiring OL[j], electrical continuity is established between the current source circuit ISC and the wiring OLB[j], electrical continuity is not established between the circuit AFP and the wiring OL[j], electrical continuity is not established between the circuit AFP and the wiring OLB[j], electrical continuity is established between the wiring VCN and the wiring OL[j], electrical continuity is not established between the wiring VCN and the wiring OLB[j], electrical continuity is not established between the wiring VCN2 and the wiring OL[j], and electrical continuity is not established between the wiring VCN2 and the wiring OLB[j]. That is, in the switching circuit TW[j], the switch SWIB and the switch SWL are turned on, and the switch SWI, the switch SWO, the switch SWOB, the switch SWLB, the switch SWH, and the switch SWHB are turned off. Accordingly, electrical continuity is established between the current source circuit ISC and the wiring OLB[j], so that a current can flow from the current source circuit ISC to the circuit MP through the wiring OLB[j]. When the number of constant current sources in the current source circuit ISC is P, the current has any one of 2P−1 levels (zero current is not included). Since the negative weight coefficient input to the circuit MP is determined in accordance with the current, the weight coefficient can have any one of 2P−1 values. In addition, electrical continuity is established between the wiring VCN and the wiring OL[j], so that a constant voltage is input from the wiring VCN to the wiring OL[j].
When a weight coefficient of 0 is to be input to the circuit MP, a constant potential supplied from the wiring VCN is input to each of the wiring OL[j] and the wiring OLB[j]. For example, electrical continuity is not established between the current source circuit ISC and the wiring OL[j], electrical continuity is not established between the current source circuit ISC and the wiring OLB[j], electrical continuity is not established between the circuit AFP and the wiring OL[j], electrical continuity is not established between the circuit AFP and the wiring OLB[j], electrical continuity is established between the wiring VCN and the wiring OL[j], electrical continuity is established between the wiring VCN and the wiring OLB[j], electrical continuity is not established between the wiring VCN2 and the wiring OL[j], and electrical continuity is not established between the wiring VCN2 and the wiring OLB[j]. That is, in the switching circuit TW[j], the switch SWL and the switch SWLB are turned on, and the switch SWI, the switch SWIB, the switch SWO, the switch SWOB, the switch SWH, and the switch SWHB are turned off. Accordingly, electrical continuity is established between the wiring VCN and the wiring OL[j] and electrical continuity is established between the wiring VCN and the wiring OLB[j], so that a constant voltage is input from the wiring VCN to the wirings OL[j] and OLB[j].
That is, when the number of constant current sources in the current source circuit ISC is P, the number of weight coefficients (a positive weight coefficient, a negative weight coefficient, and a weight coefficient of 0) that can be input to the circuit MP is 2P+1−1.
Next, the case where information (e.g., a potential or a current) is supplied from the circuit MP to the circuit AFP is described.
Before information (e.g., a potential or a current) is supplied from the circuit MP to the circuit AFP, the wiring OL[j] and the wiring OLB[j] are preferably set to have a predetermined potential. For example, in the case where a positive current flows from the circuit AFP to the circuit MP through the wiring OL or the wiring OLB, the predetermined potential is preferably a high-level potential. As another example, in the case where a positive current flows from the circuit MP to the circuit AFP through the wiring OL or the wiring OLB, the predetermined potential is preferably a low-level potential. Thus, before information (e.g., a potential or a current) is supplied from the circuit MP to the circuit AFP, for example, electrical continuity is not established between the current source circuit ISC and the wiring OL[j], electrical continuity is not established between the current source circuit ISC and the wiring OLB[j], electrical continuity is not established between the circuit AFP and the wiring OL[j], electrical continuity is not established between the circuit AFP and the wiring OLB[j], electrical continuity is not established between the wiring VCN and the wiring OL[j], electrical continuity is not established between the wiring VCN and the wiring OLB[j], electrical continuity is established between the wiring VCN2 and the wiring OL[j], and electrical continuity is established between the wiring VCN2 and the wiring OLB[j]. That is, in the switching circuit TW[j], the switch SWH and the switch SWHB are turned on, and the switch SWI, the switch SWIB, the switch SWO, the switch SWOB, the switch SWL, and the switch SWLB are turned off. Accordingly, electrical continuity is established between the wiring OL[j] and the wiring VCN2 and electrical continuity is established between the wiring OLB[j] and the wiring VCN2, so that a constant voltage is input from the wiring VCN2 to the wiring OL[j] and the wiring OLB[j].
When information (e.g., a potential or a current) is supplied from the circuit MP[i,j] to the circuit AFP, for example, electrical continuity is not established between the current source circuit ISC and the wiring OL[j], electrical continuity is not established between the current source circuit ISC and the wiring OLB[j], electrical continuity is established between the circuit AFP and the wiring OL[j], electrical continuity is established between the circuit AFP and the wiring OLB[j], electrical continuity is not established between the wiring VCN and the wiring OL[j], electrical continuity is not established between the wiring VCN and the wiring OLB[j], electrical continuity is not established between the wiring VCN2 and the wiring OL[j], and electrical continuity is not established between the wiring VCN2 and the wiring OLB[j]. That is, in the switching circuit TW[j], the switch SWO and the switch SWOB are turned on, and the switch SWI, the switch SWIB, the switch SWL, the switch SWLB, the switch SWH, and the switch SWHB are turned off. Accordingly, electrical continuity is established between the circuit AFP and the circuit MP[i,j], so that information (e.g., a potential or a current) can be supplied from the circuit MP[i,j] to the circuit AFP.
As described above, with the circuit ILD and the switching circuit TW[j] having the configurations illustrated in
Next, configuration examples of the circuit MP[i,j] included in the arithmetic circuit 110, the arithmetic circuit 120, the arithmetic circuit 130, and the arithmetic circuit 140 are described.
The circuit MC includes a circuit HC and the circuit MCr includes a circuit HCr, for example. The circuit HC and the circuit HCr each have a function of holding information (e.g., a potential, a resistance value, or a current value). Note that the first data wi(k-1)j(k) set in the circuit MP[i,j] is determined in accordance with information (e.g., a potential, a resistance value, or a current value) held in the circuit HC and the circuit HCr. Therefore, the circuit HC and the circuit HCr are electrically connected to the wiring OL[j] and the wiring OLB[j] that supply information (e.g., a potential, a resistance value, or a current value) corresponding to the first data wi(k-1)j(k).
In
A wiring WL[i] illustrated in
The case where the first data wi(k-1)j(k) has any one of three levels “−1”, “0”, and “1” is considered, for example. In the case where the first data wi(k-1)j(k) is “1”, for example, a predetermined potential is held in the circuit HC so that a current corresponding to “1” flows from the wiring OL[j] to the wiring VE[j] through the circuit MC, and a potential V0 is held in the circuit HCr so that a current does not flow from the wiring OLB[j] to the wiring VEr[j] through the circuit MCr. In the case where the first data wi(k-1)j(k) is “−1”, for example, the potential V0 is held in the circuit HC so that a current does not flow from the wiring OL[j] to the wiring VE[j] through the circuit MC, and a predetermined potential is held in the circuit HCr so that a current corresponding to “−1” flows from the wiring OLB[j] to the wiring VEr[j] through the circuit MCr. In the case where the first data wi(k-1)j(k) is “0”, for example, the potential V0 is held in the circuit HC so that a current does not flow from the wiring OL[j] to the wiring VE[j] through the circuit MC, and the potential V0 is held in the circuit HCr so that a current does not flow from the wiring OLB[j] to the wiring VEr[j] through the circuit MCr. Note that the potential V0 can be a potential supplied from the wiring VCN in the description of
As another example, the case where the first data wi(k-1)j(k) is an analog value, specifically, a “negative analog value”, “0”, or a “positive analog value” is considered. In the case where the first data wi(k-1)j(k) is a “positive analog value”, for example, a predetermined potential is held in the circuit HC so that an analog current corresponding to the “positive analog value” flows from the wiring OL[j] to the wiring VE[j] through the circuit MC, and the potential V0 is held in the circuit HCr so that a current does not flow from the wiring OLB[j] to the wiring VEr[j] through the circuit MCr. In the case where the first data wi(k-1)j(k) is a “negative analog value”, for example, the potential V0 is held in the circuit HC so that a current does not flow from the wiring OL[j] to the wiring VE[j] through the circuit MC, and a predetermined potential is held in the circuit HCr so that an analog current corresponding to the “negative analog value” flows from the wiring OLB[j] to the wiring VEr[j] through the circuit MCr. In the case where the first data wi(k-1)j(k) is “0”, for example, the potential V0 is held in the circuit HC so that a current does not flow from the wiring OL[j] to the wiring VE[j] through the circuit MC, and the potential V0 is held in the circuit HCr so that a current does not flow from the wiring OLB[j] to the wiring VEr[j] through the circuit MCr. Note that as in the above example, the potential V0 can be a potential supplied from the wiring VCN in the description of
In addition, for example, the circuit MC has a function of outputting a current or the like corresponding to information (e.g., a potential, a resistance value, or a current value) held in the circuit HC to one of the wiring OL[j] and the wiring OLB[j], and the circuit MCr has a function of outputting a current or the like corresponding to information (e.g., a potential, a resistance value, or a current value) held in the circuit HCr to the other of the wiring OL[j] and the wiring OLB[j]. For example, in the case where a first potential is held in the circuit HC, the circuit MC supplies a current having a first current value from the wiring OL[j] or the wiring OLB[j] to the wiring VE, and in the case where a second potential is held in the circuit HC, the circuit MC supplies a current having a second current value from the wiring OL[j] or the wiring OLB[j] to the wiring VE. Similarly, in the case where the first potential is held in the circuit HCr, the circuit MCr supplies a current having the first current value from the wiring OL[j] or the wiring OLB[j] to the wiring VEr, and in the case where the second potential is held in the circuit HCr, the circuit MCr supplies a current having the second current value from the wiring OL[j] or the wiring OLB[j] to the wiring VEr. Note that the levels of the first current value and the second current value are each determined in accordance with the value of the first data wi(k-1)j(k). For example, the first current value may be larger than or smaller than the second current value. In addition, for example, one of the first current value and the second current value may be zero current; that is, the current value may be 0. Moreover, the direction in which current flows may be different between a current having the first current value and a current having the second current value.
In particular, in the case where the first data wi(k-1)j(k) has any one of three levels “−1”, “0”, and “1”, the circuit MC and the circuit MCr are preferably configured so that one of the first current value and the second current value is 0. Note that in the case where the first data wi(k-1)j(k) is an analog value, e.g., a “negative analog value”, “0”, or a “positive analog value”, the first current value or the second current value can be an analog value, for example.
In the case where a current flowing from the wiring OL[j] or the wiring OLB[j] to the wiring VE through the circuit MC and a current flowing from the wiring OL[j] or the wiring OLB[j] to the wiring VEr through the circuit MCr are made equal to each other, a potential held in the circuit MC and a potential held in the circuit MCr might not be equal to each other because transistors therein sometimes have variations in their characteristics caused in a fabrication process or the like of the transistors. In the semiconductor device of one embodiment of the present invention, the amount of current flowing from the wiring OL[j] or the wiring OLB[j] to the wiring VE through the circuit MC can be almost equal to the amount of current flowing from the wiring OL[j] or the wiring OLB[j] to the wiring VEr through the circuit MCr, even when there are variations in characteristics of the transistors.
Note that in this specification and the like, a current, a voltage, or the like corresponding to information (e.g., a potential, a resistance value, or a current value) held in the circuit HC and the circuit HCr may be a positive current, voltage, or the like, may be a negative current, voltage, or the like, or may be zero current, zero voltage, or the like; alternatively, a positive one, a negative one, and 0 may be mixed. That is, for example, the above description “the circuit MC has a function of outputting a current, a voltage, or the like corresponding to information (e.g., a potential, a resistance value, or a current value) held in the circuit HC to one of the wiring OL[j] and the wiring OLB[j], and the circuit MCr has a function of outputting a current, a voltage, or the like corresponding to information (e.g., a potential, a resistance value, or a current value) held in the circuit HCr to the other of the wiring OL[j] and the wiring OLB[j]” can be rephrased as a description “the circuit MC has a function of releasing a current, a voltage, or the like corresponding to information (e.g., a potential, a resistance value, or a current value) held in the circuit HC from one of the wiring OL[j] and the wiring OLB[j], and the circuit MCr has a function of releasing a current corresponding to information (e.g., a potential, a resistance value, or a current value) held in the circuit HCr from the other of the wiring OL[j] and the wiring OLB[j]”.
The wiring X1L[i] and a wiring X2L[i] illustrated in
The circuit MC is electrically connected to the wiring OL[j] and the wiring OLB[j], and the circuit MCr is electrically connected to the wiring OL[j] and the wiring OLB[j]. The circuit MC and the circuit MCr output currents, potentials, or the like corresponding to the product of the first data wi(k-1)j(k) and the second data zi(k-1) to the wiring OL[j] and the wiring OLB[j] in accordance with potentials, currents, or the like input to the wiring X1L[i] and the wiring X2L[i], for example. As a specific example, the destinations of the currents output from the circuit MC and the circuit MCr are determined in accordance with the potentials of the wiring X1L[i] and the wiring X2L[i]. For example, the circuit MC and the circuit MCr have a circuit configuration in which a current output from the circuit MC flows to one of the wiring OL[j] and the wiring OLB[j], and a current output from the circuit MCr flows to the other of the wiring OL[j] and the wiring OLB[j]. That is, the currents output from the circuit MC and the circuit MCr flow to not the same wiring but different wirings. Note that for example, the currents from the circuit MC and the circuit MCr flow to neither the wiring OL[j] nor the wiring OLB[j] in some cases.
The case where the second data zi(k-1) has any one of three levels “−1”, “0”, and “1” is considered, for example. In the case where the second data zi(k-1) is “1”, for example, the circuit MP establishes electrical continuity between the circuit MC and the wiring OL[j] and establishes electrical continuity between the circuit MCr and the wiring OLB[j]. In the case where the second data zi(k-1) is “−1”, for example, the circuit MP establishes electrical continuity between the circuit MC and the wiring OLB[j] and establishes electrical continuity between the circuit MCr and the wiring OL[j]. In the case where the second data zi(k-1) is “0”, for example, the circuit MP breaks electrical continuity between the circuit MC and the wiring OL[j] and between the circuit MC and the wiring OLB[j] and breaks electrical continuity between the circuit MCr and the wiring OL[j] and between the circuit MC and the wiring OLB[j] so that currents output from the circuit MC and the circuit MCr flow to neither the wiring OL[j] nor the wiring OLB[j].
An example in which the above-described operations are combined is shown. In the case where the first data wi(k-1)j(k) is “1”, a current flows from the wiring OL[j] or the wiring OLB[j] to the wiring VE[j] through the circuit MC in some cases, and a current does not flow from the wiring OL[j] or the wiring OLB[j] to the wiring VEr[j] through the circuit MCr. In the case where the first data wi(k-1)j(k) is “−1”, a current does not flow from the wiring OL[j] or the wiring OLB[j] to the wiring VE[j] through the circuit MC, and a current flows from the wiring OL[j] or the wiring OLB[j] to the wiring VEr[j] through the circuit MCr in some cases. In the case where the second data zi(k-1) is “1”, electrical continuity is established between the circuit MC and the wiring OL[j] and between the circuit MCr and the wiring OLB[j]. In the case where the second data zi(k-1) is “−1”, electrical continuity is established between the circuit MC and the wiring OLB[j] and between the circuit MCr and the wiring OL[j]. From the above, in the case where the product of the first data wi(k-1)j(k) and the second data zi(k-1) is a positive value, a current flows from the wiring OL[j] to the wiring VE[j] through the circuit MC or a current flows from the wiring OL[j] to the wiring VEr[j] through the circuit MCr. In the case where the product of the first data wi(k-1)j(k) and the second data zi(k-1) is a negative value, a current flows from the wiring OL[j] to the wiring VEr[j] through the circuit MCr or a current flows from the wiring OLB[j] to the wiring VE[j] through the circuit MC. In the case where the product of the first data wi(k-1)j(k) and the second data zi(k-1) is a value of 0, a current does not flow from the wiring OL[j] or the wiring OLB[j] to the wiring VE[j] and a current does not flow from the wiring OL[j] or the wiring OLB[j] to the wiring VEr[j].
Specific examples of the above-described example is as follows: in the case where the first data wi(k-1)j(k) is “1” and the second data zi(k-1) is “1”, a current I1[i,j] having the first current value flows from the circuit MC to the wiring OL[j] and a current I2[i,j] having the second current value flows from the circuit MCr to the wiring OLB[j], for example. Here, the second current value is zero, for example. In the case where the first data wi(k-1)j(k) is “−1” and the second data zi(k-1) is “1”, the current I1[i,j] having the second current value flows from the circuit MC to the wiring OL[j] and the current I2[i,j] having the first current value flows from the circuit MCr to the wiring OLB[j], for example. Here, the second current value is zero, for example. In the case where the first data wi(k-1)j(k) is “0” and the second data zi(k-1) is “1”, the current I1[i,j] having the second current value flows from the circuit MC to the wiring OL[j] and the current I2[i,j] having the second current value flows from the circuit MCr to the wiring OLB[j]. Here, the second current value is zero, for example.
In the case where the first data wi(k-1)j(k) is “1” and the second data zi(k-1) is “−1”, the current I1[i,j] having the first current value flows from the circuit MC to the wiring OLB[j] and the current I2[i,j] having the second current value flows from the circuit MCr to the wiring OL[j]. Here, the second current value is zero, for example. In the case where the first data wi(k-1)j(k) is “−1” and the second data zi(k-1) is “−1”, the current I1[i,j] having the second current value flows from the circuit MC to the wiring OLB[j] and the current I2[i,j] having the first current value flows from the circuit MCr to the wiring OL[j]. Here, the second current value is zero, for example. In the case where the first data wi(k-1)j(k) is “0” and the second data zi(k-1) is “−1”, the current I1[i,j] having the second current value flows from the circuit MC to the wiring OLB[j] and the current I2[i,j] having the second current value flows from the circuit MCr to the wiring OL[j]. Here, the second current value is zero, for example.
In the case where the second data zi(k-1) is “0”, electrical continuity is not established between the circuit MC and the wiring OL[j] and between the circuit MC and the wiring OLB[j], for example. Similarly, electrical continuity is not established between the circuit MCr and the wiring OL[j] and between the circuit MCr and the wiring OLB[j]. Therefore, regardless of the value of the first data wi(k-1)j(k), a current is not output from the circuit MC and the circuit MCr to the wiring OL[j] and the wiring OLB[j].
As described above, in the case where the product value of the first data wi(k-1)j(k) and the second data zi(k-1) is a positive value, for example, a current flows from the circuit MC or the circuit MCr to the wiring OL[j]. Here, in the case where the first data wi(k-1)j(k) is a positive value, a current flows from the circuit MC to the wiring OL[j], and in the case where the first data wi(k-1)j(k) is a negative value, a current flows from the circuit MCr to the wiring OL[j]. By contrast, in the case where the product value of the first data wi(k-1)j(k) and the second data zi(k-1) is a negative value, a current flows from the circuit MC or the circuit MCr to the wiring OLB[j]. Here, in the case where the first data wi(k-1)j(k) is a positive value, a current flows from the circuit MC to the wiring OLB[j], and in the case where the first data wi(k-1)j(k) is a negative value, a current flows from the circuit MCr to the wiring OLB[j]. Accordingly, the total amount of current output from a plurality of circuits MC or a plurality of circuits MCr connected to the wiring OL[j] flows to the wiring OL[j]. That is, a current having a value that is the sum of positive values flows through the wiring OL[j]. By contrast, the total amount of current output from a plurality of circuits MC or a plurality of circuits MCr connected to the wiring OLB[j] flows to the wiring OLB[j]. That is, a current having a value that is the sum of negative values flows through the wiring OLB[j]. As a result of the above-described operation, product-sum operation processing can be performed by utilizing the total value of the current flowing through the wiring OL[j], that is, the sum total of positive values, and the total value of the current flowing through the wiring OLB[j], that is, the sum total of negative values. For example, in the case where the total value of the current flowing through the wiring OL[j] is larger than the total value of the current flowing through the wiring OLB[j], it can be determined that the product-sum operation result has a positive value. In the case where the total value of the current flowing through the wiring OL[j] is smaller than the total value of the current flowing through the wiring OLB[j], it can be determined that the product-sum operation result has a negative value. In the case where the total value of the current flowing through the wiring OL[j] is almost equal to the total value of the current flowing through the wiring OLB[j], it can be determined that the product-sum operation result has a value of 0.
Note that also in the case where the second data zi(k-1) has any two levels among “−1”, “0”, and “1”, for example, two levels “−1” and “1” or two levels “0” and “1”, operation can be performed in a similar manner. Similarly, in the case where the first data wi(k-1)j(k) has any two levels among “−1”, “0”, and “1”, for example, two levels “−1” and “1” or two levels “0” and “1”, operation can be performed in a similar manner.
Note that the first data wi(k-1)j(k) may be an analog value or a multi-bit (multilevel) digital value. As a specific example, “−1” may be replaced with a “negative analog value”, and “1” may be replaced with a “positive analog value”. In this case, the amount of current flowing from the circuit MC or the circuit MCr is, for example, an analog value corresponding to the absolute value of the value of the first data wi(k-1)j(k).
Next, a modification example of the circuit MP[i,j] in
The circuit MP[i,j] illustrated in
The circuit MP[i,j] in
Next, a modification example of the circuit MP[i,j] in
Since the circuit MCr does not include the circuit HCr, an arithmetic circuit using the circuit MP[i,j] in
In the circuit MP[i,j] in
Note that the circuit configuration of the arithmetic circuit 110 using the circuit MP in
The circuit MP[i,j] illustrated in
The wiring W1L[i] and a wiring W2L[i] illustrated in
The wiring IL[j] is electrically connected to the circuit HC and the circuit HCr.
In the case where the circuit HC and the circuit HCr of the circuit MP[i,j] in
Note that in the case where the circuit HC and the circuit HCr hold substantially the same information (e.g., a voltage, a resistance value, or a current) (in the case where the first data wi(k-1)j(k) of the circuit MP[i,j] is set when the circuit HC and the circuit HCr hold substantially the same information), a predetermined potential is supplied to the wiring W1L[i] and the wiring W2L[i] so that electrical continuity is established between the circuit HC and the wiring IL[j] and electrical continuity is established between the circuit HCr and the wiring IL[j], and then a current, a voltage, or the like corresponding to the information is supplied from the wiring IL[j] to the circuit HC and the circuit HCr.
When a potential corresponding to the first data wi(k-1)j(k) is held in the circuit HC and the circuit HCr and a potential corresponding to the second data zi(k-1) is supplied to the wiring X1L[i] and the wiring X2L[i], the circuit MP[i,j] in
The circuit MP[i,j] illustrated in
Specifically, the circuit MP in
In the circuit MP in
Moreover, in the circuit MP in
Note that the circuit MP in
The circuit MP[i,j] illustrated in
The wiring WL[i] illustrated in
As described above, the circuit MC is not electrically connected to the wiring OLB[j] and the circuit MCr is not electrically connected to the wiring OL[j] in the circuit MP[i,j] in
Thus, the circuit MP[i,j] in
When used for the arithmetic circuit 110, the circuit MP[i,j] in
As in
The circuit MP[i,j] in
A first terminal of the transistor MZ is electrically connected to a first terminal of the circuit MC and a first terminal of the circuit MCr. A second terminal of the transistor MZ is electrically connected to a wiring VL. A gate of the transistor MZ is electrically connected to the wiring XL[i].
The wiring VL functions as a wiring for supplying a constant voltage, for example. The constant voltage is preferably determined in accordance with the configuration of the circuit MP[i,j], the arithmetic circuit 110, or the like. The constant voltage can be, for example, a high-level potential VDD, a low-level potential VSS, a ground potential, or the like.
The wiring WL[i] illustrated in
The wiring OL[j] is electrically connected to a second terminal of the circuit MC. The wiring OLB[j] is electrically connected to a second terminal of the circuit MCr.
The wiring IL[j] is electrically connected to the circuit HC, and the wiring ILB[j] is electrically connected to the circuit HCr.
For the operation of the case where a potential corresponding to the first data is held in each of the circuit HC and the circuit HCr of the circuit MP[i,j] in
In the circuit MP[i,j] in
In the case where a potential corresponding to the first data wi(k-1)j(k) of “1” is held in each of the circuit HC and the circuit HCr, for example, the circuit MC makes a predetermined current flow between the first terminal and the second terminal of the circuit MC when the constant voltage supplied from the wiring VL is supplied to the circuit MC. Thus, a current flows between the circuit MC and the wiring OL. Note that at this time, the circuit MCr does not make a current flow between the first terminal and the second terminal of the circuit MCr. Thus, a current does not flow between the circuit MCr and the wiring OLB. Moreover, in the case where a potential corresponding to the first data wi(k-1)j(k) of “−1” is held in each of the circuit HC and the circuit HCr, for example, the circuit MCr makes a predetermined current flow between the first terminal and the second terminal of the circuit MCr when the constant voltage supplied from the wiring VL is supplied to the circuit MC. Thus, a current flows between the circuit MCr and the wiring OLB. Note that at this time, the circuit MC does not make a current flow between the first terminal and the second terminal of the circuit MC. Thus, a current does not flow between the circuit MC and the wiring OL. In the case where a potential corresponding to the first data wi(k-1)j(k) of “0” is held in each of the circuit HC and the circuit HCr, for example, the circuit MC does not make a current flow between the first terminal and the second terminal of the circuit MC and the circuit MCr does not make a current flow between the first terminal and the second terminal of the circuit MCr regardless of whether the constant voltage from the wiring VL is supplied to the circuit MC and the circuit MCr. That is, a current does not flow between the circuit MC and the wiring OL and a current does not flow between the circuit MCr and the wiring OLB.
Note that for a specific example of the potential corresponding to the first data wi(k-1)j(k) that is held in the circuit HC and the circuit HCr in the circuit MP[i,j] in
The wiring XL[i] illustrated in
The case where the second data zi(k-1) has one of two levels “0” and “1” is considered, for example. In the case where the second data zi(k-1) is “1”, for example, a high-level potential is supplied to the wiring XL[i]. At this time, the transistor MZ is turned on; thus, the circuit MP establishes electrical continuity between the wiring VL and the first terminal of the circuit MC and establishes electrical continuity between the wiring VL and the first terminal of the circuit MCr. That is, in the case where the second data zi(k-1) is “1”, the constant voltage from the wiring VL is supplied to the circuit MC and the circuit MCr. Moreover, in the case where the second data zi(k-1) is “0”, for example, a low-level potential is supplied to the wiring XL[i]. At this time, the circuit MP does not establish electrical continuity between the circuit MC and the wiring OLB[j] and does not establish electrical continuity between the circuit MCr and the wiring OL[j]. That is, in the case where the second data zi(k-1) is “0”, the constant voltage from the wiring VL is not supplied to the circuit MC and the circuit MCr.
Here, in the case where the first data wi(k-1)j(k) is “1” and the second data zi(k-1) is “1”, for example, the result is that a current flows between the circuit MC and the wiring OL and a current does not flow between the circuit MCr and the wiring OLB. In the case where the first data wi(k-1)j(k) is “−1” and the second data zi(k-1) is “1”, for example, the result is that a current does not flow between the circuit MC and the wiring OL and a current flows between the circuit MCr and the wiring OLB. In the case where the first data wi(k-1)j(k) is “0” and the second data zi(k-1) is “1”, for example, the result is that a current does not flow between the circuit MC and the wiring OL and between the circuit MCr and the wiring OLB. In the case where the second data zi(k-1) is “0”, for example, the result is that a current does not flow between the circuit MC and the wiring OL and between the circuit MCr and the wiring OLB even when the first data wi(k-1)j(k) is any one of “−1”, “0”, and “1”.
That is, like the circuit MP[i,j] in
Note that the circuit MP[i,j] illustrated in
Next, an operation example of the arithmetic circuit 140 in
The arithmetic circuit 140 in
First, in the arithmetic circuit 140, the first data wi(k-1)j(k) to wm(k-1)j(k) are set in the circuit MP[1,j] to the circuit MP[m,j]. The first data wi(k-1)j(k) is set in the following manner: a predetermined potential is input to the wiring WLS[1] to the wiring WLS[m] sequentially by the circuit WLD to select the circuit MP[1,j] to the circuit MP[m,j] sequentially, and a potential, a current, or the like corresponding to the first data is supplied from the circuit ILD through the switching circuit TW[j], the wiring OL[j], and the wiring OLB[j] to the circuit HC of the circuit MC and the circuit HCr of the circuit MCr that are included in each of the selected circuits MP. After the supply of the potential, the current, or the like, the circuit WLD makes the circuit MP[1,j] to the circuit MP[m,j] unselected, so that the potential, the current, or the like corresponding to the first data wi(k-1)j(k) to wm(k-1)j(k) can be held in the circuit HC of the circuit MC and the circuit HCr of the circuit MCr that are included in each of the circuit MP[1,j] to the circuit MP[m,j]. For example, in the case where the first data wi(k-1)j(k) to wm(k-1)j(k) each be a positive value, a value corresponding to the positive value is input to the circuit HC and a value corresponding to zero is input to the circuit HCr. In contrast, in the case where the first data wi(k-1)j(k) to wm(k-1)j(k) each be a negative value, a value corresponding to zero is input to the circuit HC and a value corresponding to the absolute value of the negative value is input to the circuit HCr.
Next, the second data zi(k-1) to zm(k-1) are supplied to the wiring X1L[1] to the wiring X1L[m] and the wiring X2L[1] to the wiring X2L[m] by the circuit XLD. As a specific example, the second data zi(k-1) is supplied to the wiring X1L[i] and the wiring X2L[i]. Note that the wiring X1L[i] and the wiring X2L[i] correspond to the wiring XLS[i] of the arithmetic circuit 140 illustrated in
Electrical continuity between the circuit MC and the circuit MCr included in each of the circuit MP[1,j] to the circuit MP[m,j] and the wiring OL[j] and the wiring OLB[j] is determined in accordance with the second data zi(k-1) to zm(k-1) input respectively to the circuit MP[1,j] to the circuit MP[m,j]. As a specific example, in accordance with the second data zi(k-1), the circuit MP[i,j] is in any one of a state where “electrical continuity is established between the circuit MC and the wiring OL[j] and electrical continuity is established between the circuit MCr and the wiring OLB[j]”, a state where “electrical continuity is established between the circuit MC and the wiring OLB[j] and electrical continuity is established between the circuit MCr and the wiring OL[j]”, and a state where “electrical continuity between each of the circuit MC and the circuit MCr and the wiring OL[j] and the wiring OLB[j] is not established”. For example, in the case where the second data zi(k-1) has a positive value, a value with which electrical continuity can be established between the circuit MC and the wiring OL[j] and electrical continuity can be established between the circuit MCr and the wiring OLB[j] is input to the wiring X1L[1]. Then, a value with which electrical continuity cannot be established between the circuit MC and the wiring OLB[j] and electrical continuity cannot be established between the circuit MCr and the wiring OL[j] is input to the wiring X2L[1]. In the case where the second data zi(k-1) has a negative value, a value with which electrical continuity can be established between the circuit MC and the wiring OLB[j] and electrical continuity can be established between the circuit MCr and the wiring OL[j] is input to the wiring X1L[1]. Then, a value with which electrical continuity cannot be established between the circuit MC and the wiring OL[j] and electrical continuity cannot be established between the circuit MCr and the wiring OLB[j] is input to the wiring X2L[1]. In the case where the second data zi(k-1) has a value of 0, a value with which electrical continuity cannot be established between the circuit MC and the wiring OLB[j] and electrical continuity cannot be established between the circuit MCr and the wiring OL[j] is input to the wiring X1L[1]. Then, a value with which electrical continuity cannot be established between the circuit MC and the wiring OL[j] and electrical continuity cannot be established between the circuit MCr and the wiring OLB[j] is input to the wiring X2L[1].
Electrical continuity or electrical discontinuity between the circuit MC and the circuit MCr that are included in the circuit MP[i,j] and the wiring OL[j] and the wiring OLB[j] is determined in accordance with the second data zi(k-1) input to the circuit MP[i,j], whereby currents are input and output between the circuit MC and the circuit MCr and the wiring OL[j] and the wiring OLB[j]. Furthermore, the amount of the currents is determined in accordance with the first data wi(k-1)j(k) and/or the second data zi(k-1) set in the circuit MP[i,j].
For example, in the circuit MP[i,j], a current flowing from the wiring OL[j] to the circuit MC or the circuit MCr is I[i,j], and a current flowing from the wiring OLB[j] to the circuit MC or the circuit MCr is IB[i,j]. When a current flowing from the circuit ACTF[j] to the wiring OL[j] is Iout[j] and a current flowing from the wiring OLB[j] to the circuit ACTF[j] is IBout[j], Iout[j] and IBout[j] can be expressed by the following formulae.
In the circuit MP[i,j], the circuit MC releases I(+1) and the circuit MCr releases I(−1) in the case where the first data wi(k-1)j(k) is “+1”, the circuit MC releases I(−1) and the circuit MCr releases I(+1) in the case where the first data wi(k-1)j(k) is “−1”, and the circuit MC releases I(−1) and the circuit MCr releases I(−1) in the case where the first data wi(k-1)j(k) is “0”, for example.
Furthermore, the circuit MP[i,j] is in a state where “electrical continuity is established between the circuit MC and the wiring OL[j], electrical continuity is established between the circuit MCr and the wiring OLB[j], electrical continuity is broken between the circuit MC and the wiring OLB[j], and electrical continuity is broken between the circuit MCr and the wiring OL[j]” in the case where the second data zi(k-1) is “+1”; the circuit MP[i,j] is in a state where “electrical continuity is established between the circuit MC and the wiring OLB[j], electrical continuity is established between the circuit MCr and the wiring OL[j], electrical continuity is broken between the circuit MC and the wiring OL[j], and electrical continuity is broken between the circuit MCr and the wiring OLB[j]” in the case where the second data zi(k-1) is “−1”; and the circuit MP[i,j] is in a state where “electrical continuity is broken between the circuit MC and the wiring OL[j] and between the circuit MC and the wiring OLB[j], electrical continuity is broken between the circuit MCr and the wiring OL[j] and between the circuit MCr and the wiring OLB[j], and electrical continuity is broken between the circuit MCr and the wiring OL[j] and between the circuit MCr and OLB[j]” in the case where the second data zi(k-1) is “0”.
In this case, in the circuit MP[i,j], the current I[i,j] flowing from the wiring OL[j] to the circuit MC or the circuit MCr and the current IB[i,j] flowing from the wiring OLB[j] to the circuit MC or the circuit MCr are as shown in the following table. Note that depending on the case, the circuit MP[i,j] may be configured such that the amount of current I(−1) is 0. Note that the current I[i,j] may be a current flowing from the circuit MC or the circuit MCr to the wiring OL[j]. Similarly, the current IB[i,j] may be a current flowing from the circuit MC or the circuit MCr to the wiring OLB[j].
Then, Iout[j] and IBout[j] respectively flowing from the wiring OL[j] and the wiring OLB[j] are input to the circuit ACTF[j], and the circuit ACTF[j] compares Iout[j] and IBout[j], for example. On the basis of the comparison result, the circuit ACTF[j] outputs the signal zj(k) to be transmitted from the neuron Nj(k) to a neuron in the (k+1)-th layer, for example.
The arithmetic circuit 140 in
The arithmetic circuit 110, the arithmetic circuit 120, the arithmetic circuit 130, the arithmetic circuit 140, the arithmetic circuit 150, and the arithmetic circuit 160 that are described above can each be changed into a circuit that performs not the arithmetic operation of Formula (1.2) but the arithmetic operation of Formula (1.3). Formula (1.3) corresponds to arithmetic operation in which a bias is applied to the product-sum result of Formula (1.2). Thus, a circuit for applying a bias value to the wiring OL and the wiring OLB may be provided in each of the arithmetic circuit 110, the arithmetic circuit 120, the arithmetic circuit 130, the arithmetic circuit 140, the arithmetic circuit 150, and the arithmetic circuit 160.
An arithmetic circuit 170 illustrated in
The circuit BS[j] is electrically connected to the wiring OL[j], the wiring OLB[j], a wiring WLBS, and a wiring WXBS.
Like the wiring WLS[1] to the wiring WLS[m] of the arithmetic circuit 110 in
Like the wiring XLS[1] to the wiring XLS[m] of the arithmetic circuit 110 in
In addition, like the wiring WX1L[1] to the wiring WX1L[n] of the arithmetic circuit 140 in
In the j-th column of the array portion ALP of the arithmetic circuit 170, the amount of current flowing from the circuit MP[1,j] to the circuit MP[m,j] to the wiring OL[j] and the wiring OLB[j] can be expressed by Formula (1.5) and Formula (1.6). Since the wiring OL[j] and the wiring OLB[j] are electrically connected to the circuit BS[j], when a current flowing from the circuit BS[j] to the wiring OL[j] is IBIAS[j] and a current flowing from the circuit BS[j] to the wiring OLB[j] is IBIASB[j], Formula (1.5) and Formula (1.6) can be rewritten as the following formulae.
Accordingly, Iout[j] and IBout[j] each including a bias can be generated as the arithmetic operation of Formula (1.3). In addition, when Iout[j] and IBout[j] each including a bias are input to the circuit ACTF[j], the biased output signal zj(k) from the neuron Nj(k) can be generated.
Although the arithmetic circuit 170 in
Some or all of the transistors included in the above-described array portion ALP, circuit ILD, circuit WLD, circuit XLD, circuit AFP, circuit MP, switching circuit TW, and the like are preferably OS transistors, for example. For example, a transistor whose off-state current is desired to be low, specifically, a transistor having a function of holding charge accumulated in a capacitor or the like is preferably an OS transistor. In particular, in the case where an OS transistor is used as the transistor, the OS transistor preferably has a transistor structure described particularly in Embodiment 5. For a metal oxide included in a channel formation region of the OS transistor, one or more materials selected from indium, an element M (the element M is aluminum, gallium, yttrium, or tin), and zinc can be used, for example. In particular, a metal oxide containing indium, gallium, and zinc is an intrinsic (also referred to as i-type) or substantially intrinsic semiconductor that has a wide band gap, and the carrier concentration of the metal oxide is preferably lower than or equal to 1×1018 cm−3, further preferably lower than 1×1017 cm−3, still further preferably lower than 1×1016 cm−3, yet further preferably lower than 1×1013 cm−3, yet still further preferably lower than 1×1012 cm−3. The off-state current per micrometer of channel width of the OS transistor including the metal oxide in the channel formation region can be lower than or equal to 10 aA (1×10−17 A), preferably lower than or equal to 1 aA (1×10−18 A), further preferably lower than or equal to 10 zA (1×10−20 A), still further preferably lower than or equal to 1 zA (1×10−21 A), yet further preferably lower than or equal to 100 yA (1×10−22 A). Since the carrier concentration of the metal oxide in the OS transistor is low, the off-state current remains low even when the temperature of the OS transistor is changed. For example, even when the temperature of the OS transistor is 150° C., the off-state current per micrometer of channel width can be 100 zA.
Note that one embodiment of the present invention is not limited to the above, and the transistors included in the array portion ALP, the circuit ILD, the circuit WLD, the circuit XLD, the circuit AFP, the circuit MP, the switching circuit TW, and the like are not necessarily OS transistors. Other than the OS transistor, a transistor containing silicon in a channel formation region (a Si transistor) may be used, for example. As silicon, single crystal silicon, amorphous silicon (sometimes referred to as hydrogenated amorphous silicon), microcrystalline silicon, or polycrystalline silicon can be used, for example. Other than the OS transistor and the Si transistor, it is possible to use, for example, a transistor containing Ge or the like in a channel formation region, a transistor containing a compound semiconductor such as ZnSe, CdS, GaAs, InP, GaN, or SiGe in a channel formation region, a transistor containing a carbon nanotube in a channel formation region, or a transistor containing an organic semiconductor in a channel formation region.
Note that for the metal oxides in the semiconductor layers of OS transistors, n-type semiconductors of a metal oxide containing indium (e.g., In oxide) and a metal oxide containing zinc (e.g., Zn oxide) have been manufactured, but p-type semiconductors thereof are difficult to manufacture in terms of mobility and reliability in some cases. For that reason, in the arithmetic circuit 110, the arithmetic circuit 120, the arithmetic circuit 130, the arithmetic circuit 140, the arithmetic circuit 150, the arithmetic circuit 160, and the arithmetic circuit 170, OS transistors may be used as n-channel transistors included in the array portion ALP, the circuit ILD, the circuit WLD, the circuit XLD, the circuit AFP, the circuit MP, and the like, and Si transistors may be used as p-channel transistors.
Note that this embodiment can be combined with any of the other embodiments in this specification as appropriate.
This embodiment describes specific configuration examples of the circuit MP described in Embodiment 1.
Note that in Embodiment 1, [1,1], [i,j], [m,n], or the like that indicates a position in the array portion ALP is added to the reference numeral of the circuit MP; however, in this embodiment, the addition of [1,1], [i,j], [m,n], or the like to the reference numeral of the circuit MP is omitted unless otherwise specified.
First, an example of a circuit configuration that can be applied to the circuit MP in
In the circuit MP in
The transistor M1 to the transistor M4 illustrated in
The semiconductor device of one embodiment of the present invention does not depend on the connection configuration of aback gate of a transistor. In the transistor M1 to the transistor M4 illustrated in
The semiconductor device of one embodiment of the present invention does not depend on the structure of a transistor included in the semiconductor device. For example, the transistor M1 to the transistor M4 illustrated in
In this specification and the like, transistors with a variety of structures can be used as a transistor. Thus, there is no limitation on the type of transistors used. Examples of the transistor include a transistor including single crystal silicon and a transistor including a non-single-crystal semiconductor film typified by amorphous silicon, polycrystalline silicon, microcrystalline (also referred to as microcrystal, nanocrystal, or semi-amorphous) silicon, or the like. Alternatively, a thin film transistor (TFT) including a thin film of any of these semiconductors can be used, for example. The use of the TFT has various advantages. For example, since the TFT can be manufactured at a lower temperature than the case of using single crystal silicon, manufacturing costs can be reduced or a larger manufacturing apparatus can be used. Since a larger manufacturing apparatus can be used, TFTs can be manufactured over a large substrate. This enables a large number of display devices to be manufactured at a time, resulting in low cost manufacturing. Alternatively, a low manufacturing temperature allows the use of a low heat-resistance substrate. Thus, transistors can be manufactured over a light-transmitting substrate. Alternatively, transmission of light in a display element can be controlled using the transistor over a light-transmitting substrate. Alternatively, some of the films included in the transistor can transmit light because the transistor is thin. Accordingly, the aperture ratio can be increased.
For example, a transistor including a compound semiconductor (e.g., SiGe or GaAs) or an oxide semiconductor (e.g., Zn—O, In—Ga—Zn—O, In—Zn—O, In—Sn—O (ITO), Sn—O, Ti—O, Al—Zn—Sn—O (AZTO), or In—Sn—Zn—O) can be used. Alternatively, a thin film transistor including a thin film of such a compound semiconductor or oxide semiconductor can be used, for example. Accordingly, manufacturing temperature can be lowered and, for example, such a transistor can be manufactured at room temperature. As a result, the transistor can be formed directly on a substrate having low heat resistance, such as a plastic substrate or a film substrate. Note that such a compound semiconductor or oxide semiconductor can be used not only for a channel portion of the transistor but also for other applications. For example, such a compound semiconductor or oxide semiconductor can be used for a wiring, a resistor, a pixel electrode, or a light-transmitting electrode. Since such components can be deposited or formed at the same time as the transistor, the cost can be reduced.
As another example, a transistor formed by an inkjet method or a printing method can be used. The transistor can be manufactured at room temperature, manufactured at a low vacuum degree, or manufactured over a large substrate. Accordingly, the transistor can be manufactured without using a mask (reticle), so that the layout of the transistor can be easily changed. Alternatively, since the transistor can be manufactured without using a resist, the material cost is reduced, and the number of steps can be reduced. Alternatively, since a film can be formed only where needed, a material is not wasted as compared with a manufacturing method by which etching is performed after the film is formed over the entire surface; thus, the cost can be reduced.
As another example, a transistor containing an organic semiconductor, a carbon nanotube, or the like can be used. Thus, a transistor can be formed over a bendable substrate. A device using a transistor containing an organic semiconductor, a carbon nanotube, or the like can be highly resistant to impact.
Note that a transistor with any of a variety of other structures can also be used. For example, a MOS transistor, a junction transistor, a bipolar transistor, or the like can be used as the transistor. By using a MOS transistor as the transistor, the size of the transistor can be reduced. Thus, a large number of transistors can be mounted. By using a bipolar transistor as the transistor, a large amount of current can flow therethrough. Thus, a circuit can operate at high speed. Note that a MOS transistor and a bipolar transistor may be formed over one substrate. Thus, a reduction in power consumption, a reduction in size, high-speed operation, and the like can be achieved.
As another example, it is possible to use a transistor having a structure in which gate electrodes are placed over and under an active layer. With the structure in which the gate electrodes are placed over and under the active layer, a circuit configuration is such that a plurality of transistors are connected in parallel. Thus, a channel formation region is increased, so that the amount of current can be increased. Alternatively, with the structure in which the gate electrodes are placed over and under the active layer, a depletion layer can be easily formed, so that subthreshold swing can be improved.
As another example, it is possible to use a transistor having a structure in which a gate electrode is placed over an active layer, a structure in which a gate electrode is placed under an active layer, a staggered structure, an inverted staggered structure, a structure in which a channel region is divided into a plurality of regions, a structure in which active layers are connected in parallel, a structure in which active layers are connected in series, or the like. Alternatively, a transistor can have a variety of structures such as a planar type, a FIN-type, a TRI-GATE type, a top-gate type, a bottom-gate type, and a double-gate type (with gates placed over and under a channel).
As another example, it is possible to use a transistor having a structure in which at least one of a source electrode and a drain electrode overlaps with an active layer (or part thereof). Employing the structure in which at least one of the source electrode and the drain electrode overlaps with the active layer (or part thereof) can prevent unstable operation due to charge accumulation in part of the active layer.
As another example, it is possible to use a transistor having a structure in which an LDD region is provided. By providing the LDD region, it is possible to achieve a reduction in off-state current or an increase in withstand voltage (an improvement in reliability) of the transistor. Alternatively, by providing the LDD region, in the case of operation in a saturation region, the drain current does not change much even if the drain-source voltage changes, and thus the voltage-current characteristics having a flat slope can be obtained.
In this specification and the like, a transistor can be formed using a variety of substrates, for example. The type of the substrate is not limited to a certain type. Examples of the substrate include a semiconductor substrate (e.g., a single crystal substrate or a silicon substrate), an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a sapphire glass substrate, a metal substrate, a stainless steel substrate, a substrate including stainless steel foil, a tungsten substrate, a substrate including tungsten foil, a flexible substrate, an attachment film, paper including a fibrous material, and a base material film. Examples of the glass substrate include barium borosilicate glass, aluminoborosilicate glass, and soda lime glass. As examples of the flexible substrate, the attachment film, the base material film, and the like, the following can be given. The examples include plastics typified by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES), and polytetrafluoroethylene (PTFE). Another example is a synthetic resin such as acrylic. Other examples include polypropylene, polyester, polyvinyl fluoride, and polyvinyl chloride. Other examples include polyamide, polyimide, aramid, an epoxy resin, an inorganic vapor deposition film, and paper. In particular, the use of a semiconductor substrate, a single crystal substrate, an SOI substrate, or the like enables the manufacture of small-sized transistors with a small variation in characteristics, size, shape, or the like and with high current capability. When a circuit is formed with such transistors, lower power consumption of the circuit or higher integration of the circuit can be achieved.
Alternatively, a flexible substrate may be used as the substrate, and a transistor may be directly formed over the flexible substrate. Alternatively, a separation layer may be provided between the substrate and the transistor. After part or the whole of a semiconductor device is completed over the separation layer, the separation layer can be used for separation from the substrate and transfer to another substrate. In that case, the transistor can be transferred to even a substrate having low heat resistance, a flexible substrate, or the like. As the separation layer, a stacked-layer structure of inorganic films of a tungsten film and a silicon oxide film, or a structure in which an organic resin film of polyimide or the like is formed over a substrate can be used, for example.
In other words, the transistor may be formed using one substrate and then transferred to another substrate; thus, the transistor may be positioned over another substrate. Examples of the substrate to which the transistor is transferred include, in addition to the above-described substrates where the transistor can be formed, a paper substrate, a cellophane substrate, an aramid film substrate, a polyimide film substrate, a stone substrate, a wood substrate, a cloth substrate (including a natural fiber (silk, cotton, or hemp), a synthetic fiber (nylon, polyurethane, or polyester), a regenerated fiber (acetate, cupro, rayon, or regenerated polyester), or the like), a leather substrate, and a rubber substrate. When such a substrate is used, forming a transistor with excellent characteristics, forming a transistor with low power consumption, manufacturing a device with high durability, providing high heat resistance, reducing weight, or reducing thickness can be achieved.
Note that all the circuits necessary to achieve a predetermined function can be formed over one substrate (e.g., a glass substrate, a plastic substrate, a single crystal substrate, or an SOI substrate). In this manner, the cost can be reduced by a reduction in the number of components or the reliability can be improved by a reduction in the number of connection points to circuit components.
Note that it is possible that not all the circuits necessary to achieve a predetermined function are formed over one substrate. That is, it is possible to form part of the circuits necessary to achieve the predetermined function over a given substrate and form the other part of the circuits necessary to achieve the predetermined function over another substrate. For example, part of the circuits necessary to achieve the predetermined function can be formed over a glass substrate, and the other part of the circuits necessary to achieve the predetermined function can be formed on a single crystal substrate (or an SOI substrate). The single crystal substrate where the other part of the circuits necessary to achieve the predetermined function is formed (also referred to as an IC chip) can be connected to the glass substrate by COG (Chip On Glass), and the IC chip can be placed over the glass substrate. Alternatively, the IC chip can be connected to the glass substrate by TAB (Tape Automated Bonding), COF (Chip On Film), or SMT (Surface Mount Technology), or using a printed circuit board, for example. When part of the circuits is formed over the same substrate as a pixel portion in this manner, the cost can be reduced by a reduction in the number of components or the reliability can be improved by a reduction in the number of connection points to circuit components. In particular, a circuit in a portion where the driving voltage is high, a circuit in a portion where the driving frequency is high, or the like consumes much power in many cases. In view of this, such a circuit is formed over a substrate (e.g., a single crystal substrate) different from a substrate where a pixel portion is formed, whereby an IC chip is formed. The use of this IC chip can prevent the increase in power consumption.
In the circuit MP in
The connection configuration of the circuit MCr different from that of the circuit MC is described. A second terminal of a transistor M3r is electrically connected to not the wiring OL but the wiring OLB, and a second terminal of a transistor M4r is electrically connected to not the wiring OLB but the wiring OL. A first terminal of a transistor M1r and a first terminal of a capacitor C1r are electrically connected to the wiring VEr.
Note that as illustrated in
Note that in the circuit HC illustrated in
As described in Embodiment 1, the circuit HC has a function of holding a potential corresponding to the first data, for example. The potential is held in the circuit HC included in the circuit MC in
As the transistor M1, a transistor with a low off-state current is preferably used to hold the potential of the node n1 for a long time. As the transistor with a low off-state current, an OS transistor can be used, for example. Alternatively, a transistor including aback gate may be used as the transistor M1, and an off-state current may be reduced by applying a low-level potential to the back gate to shift the threshold voltage to the positive side.
In order to simply describe a current input to or output from the circuit MP in an operation example described below, both ends of the wiring OL illustrated in
The wiring VE functions as a wiring for supplying a constant voltage, for example. In the case where the transistor M3, the transistor M3r, the transistor M4, or the transistor M4r is an n-channel transistor and/or in the case where a potential supplied from the wiring VSO is a high-level potential in
The constant voltages supplied from the wiring VE, the wiring VEm, the wiring VEr, and the wiring VEmr may be different from each other, or some or all of them may be the same. In the case where the voltages supplied from the wirings are the same, the wirings can be selected and combined into one wiring. For example, in the case where the constant voltages supplied from the wiring VE, the wiring VEm, the wiring VEr, and the wiring VEmr are almost equal to each other, the wiring VEm, the wiring VEr, and the wiring VEmr can be combined with the wiring VE, as in the circuit MP in
The configuration of the circuit MP in
Similarly, the transistor M2 may also be replaced with a p-channel transistor (not illustrated).
Alternatively, as illustrated in
Alternatively, as illustrated in
It is preferable that the sizes, e.g., the channel lengths and the channel widths, of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r illustrated in
Next, operation examples of the circuit MP illustrated in
In this operation example, the constant voltage supplied by each of the wiring VE and the wiring VEr is VSS (a low-level potential). In this case, in
In this operation example, a potential supplied from the wiring VCN in
In the circuit MP illustrated in
When a current amount of I1 is supplied from the wiring OL to the wiring VE through the circuit MC while the transistor M2 and the transistor M3 are in an off state, the potential of the gate of the transistor M1 (the node n1) becomes V1. Here, the transistor M2 is turned off, so that V1 is held in the circuit HC. Accordingly, the transistor M1 can make I1, which is the current amount corresponding to the potential VSS of the first terminal of the transistor M1 and the potential V1 of the gate of the transistor M1, flow between a source and a drain of the transistor M1. In this specification and the like, such an operation is expressed as “the transistor M1 is set such that the current amount of I1 is supplied between the source and the drain of the transistor M1”, or “the transistor M1 is programmed such that the current amount of I1 is supplied between the source and the drain of the transistor M1”, for example.
In this operation example, the amount of current flowing from the wiring OL to the circuit MC has three levels of 0, I1, and I2. Accordingly, the amount of current set in the transistor M1 has the three levels of 0, I1, and I2. For example, when the potential of the gate of the transistor M1 held in the circuit HC is VSS, the potentials of the first terminal and the second terminal of the transistor M1 are each VSS, and thus the transistor M1 is turned off when the threshold voltage of the transistor M1 is higher than 0. In this case, a current does not flow between the source and the drain of the transistor M1, which can be said that the amount of current flowing between the source and the drain of the transistor M1 is set to 0. As another example, when the potential of the gate of the transistor M1 held in the circuit HC is V1 and the threshold voltage of the transistor M1 is lower than V1-VSS, the transistor M1 is turned on. Here, the amount of current flowing through the transistor M1 is I1. Thus, when the potential of the gate of the transistor M1 is V1, it can be said that the amount of current flowing between the source and the drain of the transistor M1 is set to I1. As another example, when the potential of the gate of the transistor M1 held in the circuit HC is V2 and the threshold voltage of the transistor M1 is lower than V2-VSS, the transistor M1 is turned on. Here, the amount of current flowing through the transistor M1 is 12. Thus, when the potential of the gate of the transistor M1 is V2, it can be said that the amount of current flowing between the source and the drain of the transistor M1 is set to I2.
Note that the current amount I1 is larger than 0 and smaller than I2. The potential V1 is higher than VSS and lower than V2. The threshold voltage of the transistor M1 is higher than 0 and lower than V1-VSS. Furthermore, I1 can be replaced with Iut generated by the constant current source circuit ISC1 in the description of
Before the description of the operation example, the first data (e.g., a weight coefficient here) held in the circuit MP is defined as follows. When VSS is held at the node n1 of the circuit HC and VSS is held at the node n1r of the circuit HCr, the circuit MP holds “0” as the first data (a weight coefficient). When V1 is held at the node n1 of the circuit HC and VSS is held at the node n1r of the circuit HCr, the circuit MP holds “+1” as the first data (a weight coefficient). When V2 is held at the node n1 of the circuit HC and VSS is held at the node n1r of the circuit HCr, the circuit MP holds “+2” as the first data (a weight coefficient). When VSS is held at the node n1 of the circuit HC and V1 is held at the node n1r of the circuit HCr, the circuit MP holds “−1” as the first data (a weight coefficient). When VSS is held at the node n1 of the circuit HC and V2 is held at the node n1r of the circuit HCr, the circuit MP holds “−2” as the first data (a weight coefficient).
In addition, the second data (e.g., a value of a signal of a neuron (an arithmetic value) here) input to the circuit MP is defined as follows, for example. When a high-level potential is applied to the wiring WX1L and a low-level potential is applied to the wiring X2L, “+1” is input to the circuit MP as the second data (a value of a signal of a neuron). When a low-level potential is applied to the wiring WX1L and a high-level potential is applied to the wiring X2L, “−1” is input to the circuit MP as the second data (a value of a signal of a neuron). When a low-level potential is applied to the wiring WX1L and a low-level potential is applied to the wiring X2L, “0” is input to the circuit MP as the second data (a value of a signal of a neuron). Note that the high-level potential is, for example, VDD or a potential higher than VDD by 10% or more or 20% or more.
In this specification and the like, unless otherwise specified, the transistor M1 and the transistor M1r in an on state may operate in a saturation region in the end. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in a saturation region. However, one embodiment of the present invention is not limited thereto. The transistor M1 and the transistor M1r may operate in a linear region so that the amplitude value of a voltage to be supplied is decreased. To reduce the amount of current flowing through the transistor M1 and the transistor M1r, the transistor M1 and the transistor M1r may operate in a subthreshold region. Alternatively, the transistor M1 and the transistor M1r may operate around the boundary between the saturation region and the subthreshold region. Note that in the case where the first data (a weight coefficient) is an analog value, for example, the transistor M1 and the transistor M1r may operate in the linear region, the saturation region, and the subthreshold region depending on the cases in accordance with the magnitude of the first data (weight coefficient). Alternatively, the transistor M1 and the transistor M1r may operate in both the linear region and the saturation region, may operate in both the subthreshold region and the linear region, or may operate in both the saturation region and the subthreshold region.
In this specification and the like, unless otherwise specified, the transistor M2, the transistor M2r, the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r in an on state may operate in a linear region in the end. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in the linear region. However, one embodiment of the present invention is not limited thereto. For example, the transistor M2, the transistor M2r, the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r in an on state may operate in a saturation region or may operate in a subthreshold region. Alternatively, the transistor M2, the transistor M2r, the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r may operate around the boundary between the saturation region and the subthreshold region. Alternatively, the transistor M2, the transistor M2r, the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r may operate in both the linear region and the saturation region, may operate in both the saturation region and the subthreshold region, may operate in both the subthreshold region and the linear region, or may operate in the linear region, the saturation region, and the subthreshold region.
Hereinafter, operation examples of the circuit MP are described for each combination of values that the first data (e.g., a weight coefficient below) and the second data (e.g., a value of a signal of a neuron (an arithmetic value) below) can have.
First, as an example, the case is considered where the first data (a weight coefficient) is “0” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “+1”.
From Time T1 to Time T2, an initial potential is held in the circuit HC and the circuit HCr. In
In addition, a low-level potential is applied to the wiring WL, the wiring WX1L, and the wiring X2L. Accordingly, the low-level potential is input to the gates of the transistor M2, the transistor M2r, the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r; thus, the transistor M2, the transistor M2r, the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r are turned off.
From Time T2 to Time T3, a high-level potential is applied to the wiring WL and the wiring WX1L. Accordingly, the high-level potential is input to the gates of the transistor M2, the transistor M2r, the transistor M3, and the transistor M3r; thus, the transistor M2, the transistor M2r, the transistor M3, and the transistor M3r are turned on.
Although not shown in
Note that the initialization potential Vin1 is preferably a ground potential, for example. Alternatively, the initialization potential Vin1 may be VSS, a potential higher than a ground potential, or a potential lower than a ground potential. In addition, the initialization potentials Vin1 supplied to the wiring OL and the wiring OLB may be potentials different from each other. Note that the initialization potential Vin1 is not necessarily input to the wiring OL and the wiring OLB. Note that the period from Time T2 to Time T3 is not necessarily provided. In addition, initialization is not necessarily performed from Time T2 to Time T3.
From Time T3 to Time T4, the potential VSS is input from the wiring OL to the circuit MC and the potential VSS is input from the wiring OLB to the circuit MCr. This is performed by turning on the switch SWL and the switch SWLB and turning off the switch SWI, the switch SWIB, the switch SWO, the switch SWOB, the switch SWH, and the switch SWHB in
From Time T4 to Time T5, a low-level potential is applied to the wiring WL and the wiring WX1L. Accordingly, the low-level potential is input to the gates of the transistor M2, the transistor M2r, the transistor M3, and the transistor M3r; thus, the transistor M2, the transistor M2r, the transistor M3, and the transistor M3r are turned off. When the transistor M2 and the transistor M2r are turned off, the potential VSS of the node n1 of the circuit HC is held and the potential VSS of the node n1r of the circuit HCr is held. In addition, when the transistor M3 is turned off, a current does not flow from the wiring OL to the wiring VE through the circuit MC. Similarly, when the transistor M3r is turned off, a current does not flow from the wiring OLB to the wiring VEr through the circuit MCr.
By the operation from Time T1 to Time T5, “0” is set as the first data (a weight coefficient) of the circuit MP. Moreover, after the first data (a weight coefficient) is set in the circuit MP, the switch SWI, the switch SWIB, the switch SWO, the switch SWOB, the switch SWL, and the switch SWLB in
After Time T5, as “+1” that is a signal of a neuron (an arithmetic value) input to the circuit MP, a high-level potential and a low-level potential are input to the wiring WX1L and the wiring X2L, respectively. At this time, the high-level potential is input to the gates of the transistor M3 and the transistor M3r, and the low-level potential is input to the gates of the transistor M4 and the transistor M4r. Thus, the transistor M3 and the transistor M3r are turned on and the transistor M4 and the transistor M4r are turned off. That is, by this operation, electrical continuity is established between the circuit MC and the wiring OL and between the circuit MCr and the wiring OLB, and electrical continuity is not established between the circuit MC and the wiring OLB and between the circuit MCr and the wiring OL.
At this time, in
Since the first data (a weight coefficient) is “0” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “+1” in this condition, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) obtained using Formula (1.1) is “0”. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “0” corresponds to the case where each of the current IOL and the current IOLB does not change after Time T5 in the operation of the circuit MP. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “0” is output as the signal zj(k) from the circuit AFP in
Note that processing of a plurality of product-sum operations can be performed in such a manner that only the second data (a value of a signal of a neuron, an arithmetic value, or the like) is changed while the first data (e.g., a weight coefficient) once input is not updated. In this case, the update of the first data (a weight coefficient) is unnecessary, so that power consumption can be reduced. For less frequent update of the first data (a weight coefficient), the first data (a weight coefficient) needs to be held for a long time. In this case, the use of an OS transistor with a low off-state current enables the first data (a weight coefficient) to be held for a long time, for example.
Next, as an example, the case is considered where the first data (a weight coefficient) is “+1” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “+1”.
For operation from Time T1 to Time T3, which is similar to the operation from Time T1 to Time T3 in Condition 1, the description of the operation from Time T1 to Time T3 in Condition 1 is referred to.
From Time T3 to Time T4, the current amount of I1 is input from the wiring OL to the circuit MC and the potential VSS is input from the wiring OLB to the circuit MCr. This is performed by turning on the switch SWI and the switch SWLB and turning off the switch SWIB, the switch SWO, the switch SWOB, the switch SWLB, the switch SWH, and the switch SWHB in
From Time T4 to Time T5, a low-level potential is applied to the wiring WL and the wiring WX1L. Accordingly, the low-level potential is input to the gates of the transistor M2, the transistor M2r, the transistor M3, and the transistor M3r; thus, the transistor M2, the transistor M2r, the transistor M3, and the transistor M3r are turned off. When the transistor M2 and the transistor M2r are turned off, the potential V1 of the node n1 of the circuit HC is held and the potential VSS of the node n1r of the circuit HCr is held. In addition, when the transistor M3 is turned off, a current does not flow from the wiring OL to the wiring VE through the circuit MC. Similarly, when the transistor M3r is turned off, a current does not flow from the wiring OLB to the wiring VEr through the circuit MCr.
By the operation from Time T1 to Time T5, “+1” is set as the first data (a weight coefficient) of the circuit MP. Moreover, after the first data (a weight coefficient) is set in the circuit MP, the switch SWI, the switch SWIB, the switch SWO, the switch SWOB, the switch SWL, and the switch SWLB in
After Time T5, as “+1” that is the second data (a signal of a neuron (an arithmetic value)) input to the circuit MP, a high-level potential and a low-level potential are input to the wiring WX1L and the wiring X2L, respectively. At this time, the high-level potential is input to the gates of the transistor M3 and the transistor M3r, and the low-level potential is input to the gates of the transistor M4 and the transistor M4r. Thus, the transistor M3 and the transistor M3r are turned on and the transistor M4 and the transistor M4r are turned off. That is, by this operation, electrical continuity is established between the circuit MC and the wiring OL and between the circuit MCr and the wiring OLB, and electrical continuity is not established between the circuit MC and the wiring OLB and between the circuit MCr and the wiring OL.
At this time, in
Since the first data (a weight coefficient) is “+1” and the second data (a value of a signal of a neuron) input to the circuit MP is “+1” in this condition, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) obtained using Formula (1.1) is “+1”. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “+1” corresponds to the case where the current IOL increases by I1 and the current IOLB does not change after Time T5 in the operation of the circuit MP. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “+1” is output as the signal zj(k) from the circuit AFP in
When the current flowing from the wiring OL to the circuit MC is set to not I1 but 12 from Time T3 to Time T4 in this condition, V2 can be held in the circuit HC, for example. Accordingly, “+2” is set as the first data (a weight coefficient) of the circuit MP. When the first data (a weight coefficient) is “+2” and the signal of a neuron input to the circuit MP is “+1”, the product of the first data (a weight coefficient) and the second data (a value of the signal of a neuron) obtained using Formula (1.1) is “+2”. The result that the product of the first data (a weight coefficient) and the second data (a value of the signal of a neuron) is “+2” corresponds to the case where the current IOL increases by I2 and the current IOLB does not change after Time T5 in the operation of the circuit MP. By holding VSS in the circuit HCr of the circuit MCr and setting a current amount other than I1 in the circuit MC in the above manner, a positive value other than “+1” can be set as the first data (a weight coefficient) of the circuit MP.
Next, as an example, the case is considered where the first data (a weight coefficient) is “−1” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “+1”.
For operation from Time T1 to Time T3, which is similar to the operation from Time T1 to Time T3 in Condition 1, the description of the operation from Time T1 to Time T3 in Condition 1 is referred to.
From Time T3 to Time T4, the potential VSS is input from the wiring OL to the circuit MC and the current amount of I1 is input from the wiring OLB to the circuit MCr. This is performed by turning on the switch SWIB and the switch SWL and turning off the switch SWI, the switch SWO, the switch SWOB, the switch SWLB, the switch SWH, and the switch SWHB in
From Time T4 to Time T5, a low-level potential is applied to the wiring WL and the wiring WX1L. Accordingly, the low-level potential is input to the gates of the transistor M2, the transistor M2r, the transistor M3, and the transistor M3r; thus, the transistor M2, the transistor M2r, the transistor M3, and the transistor M3r are turned off. When the transistor M2 and the transistor M2r are turned off, the potential VSS of the node n1 of the circuit HC is held and the potential V1 of the node n1r of the circuit HCr is held. In addition, when the transistor M3 is turned off, a current does not flow from the wiring OL to the wiring VE through the circuit MC. Similarly, when the transistor M3r is turned off, a current does not flow from the wiring OLB to the wiring VEr through the circuit MCr.
By the operation from Time T1 to Time T5, “−1” is set as the first data (a weight coefficient) of the circuit MP. Moreover, after the first data (a weight coefficient) is set in the circuit MP, the switch SWI, the switch SWIB, the switch SWO, the switch SWOB, the switch SWL, and the switch SWLB in
After Time T5, as “+1” that is the second data (a signal of a neuron (an arithmetic value)) input to the circuit MP, a high-level potential and a low-level potential are input to the wiring WX1L and the wiring X2L, respectively. At this time, the high-level potential is input to the gates of the transistor M3 and the transistor M3r, and the low-level potential is input to the gates of the transistor M4 and the transistor M4r. Thus, the transistor M3 and the transistor M3r are turned on and the transistor M4 and the transistor M4r are turned off. That is, by this operation, electrical continuity is established between the circuit MC and the wiring OL and between the circuit MCr and the wiring OLB, and electrical continuity is not established between the circuit MC and the wiring OLB and between the circuit MCr and the wiring OL.
At this time, in
Since the first data (a weight coefficient) is “−1” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “+1” in this condition, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) obtained using Formula (1.1) is “−1”. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “−1” corresponds to the case where the current IOL does not change and the current IOLB increases by I1 after Time T5 in the operation of the circuit MP. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “−1” is output as the signal zj(k) from the circuit AFP in
When the current flowing from the wiring OLB to the circuit MCr is set to not I1 but I2, for example, from Time T3 to Time T4 in this condition, V2 can be held in the circuit HCr. Accordingly, “−2” is set as the first data (a weight coefficient) of the circuit MP. When the first data (a weight coefficient) is set to “−2” and the second data (a value of a signal of a neuron) input to the circuit MP is set to “+1”, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) obtained using Formula (1.1) is “−2”. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “−2” corresponds to the case where the current IOL does not change and the current IOLB increases by I2 after Time T5 in the operation of the circuit MP. By holding VSS in the circuit HC of the circuit MC and setting a current amount other than I1 in the circuit MCr in the above manner, a negative value other than “−1” can be set as the weight coefficient of the circuit MP.
In this condition, as an example, the operation of the circuit MP in the case where the first data (a weight coefficient) is “0” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “−1” is considered.
For operation from Time T1 to Time T5, which is similar to the operation from Time T1 to Time T5 in Condition 1, the description of the operation from Time T1 to Time T5 in Condition 1 is referred to.
After Time T5, as “−1” that is the second data (a signal of a neuron (an arithmetic value)) input to the circuit MP, a low-level potential and a high-level potential are input to the wiring WX1L and the wiring X2L, respectively. At this time, the low-level potential is input to the gates of the transistor M3 and the transistor M3r, and the high-level potential is input to the gates of the transistor M4 and the transistor M4r. Accordingly, the transistor M3 and the transistor M3r are turned off and the transistor M4 and the transistor M4r are turned on. That is, by this operation, electrical continuity is not established between the circuit MC and the wiring OL and between the circuit MCr and the wiring OLB, and electrical continuity is established between the circuit MC and the wiring OLB and between the circuit MCr and the wiring OL.
At this time, in
Since the first data (a weight coefficient) is “0” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “−1” in this condition, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) obtained using Formula (1.1) is “0”. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “0” corresponds to the case where the current IOL and the current IOLB do not change after Time T5 in the operation of the circuit MP, which agrees with the result of the circuit operation in Condition 1. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “0” is output as the signal zj(k) from the circuit AFP in
In this condition, as an example, the operation of the circuit MP in the case where the first data (a weight coefficient) is “+1” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “−1” is considered.
For operation from Time T1 to Time T5, which is similar to the operation from Time T1 to Time T5 in Condition 2, the description of the operation from Time T1 to Time T5 in Condition 2 is referred to.
After Time T5, as “−1” that is the second data (a signal of a neuron (an arithmetic value)) input to the circuit MP, a low-level potential and a high-level potential are input to the wiring WX1L and the wiring X2L, respectively. At this time, the low-level potential is input to the gates of the transistor M3 and the transistor M3r, and the high-level potential is input to the gates of the transistor M4 and the transistor M4r. Accordingly, the transistor M3 and the transistor M3r are turned off and the transistor M4 and the transistor M4r are turned on. That is, by this operation, electrical continuity is not established between the circuit MC and the wiring OL and between the circuit MCr and the wiring OLB, and electrical continuity is established between the circuit MC and the wiring OLB and between the circuit MCr and the wiring OL.
At this time, in
Since the first data (a weight coefficient) is “+1” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “−1” in this condition, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) obtained using Formula (1.1) is “−1”. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “−1” corresponds to the case where the current IOL does not change and the current IOLB increases by I1 after Time T5 in the operation of the circuit MP, which agrees with the result of the circuit operation in Condition 3. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “−1” is output as the signal zj(k) from the circuit AFP in
Note that as described in Condition 2, from Time T3 to Time T4 in this condition, the current flowing from the wiring OL to the circuit MC may be set to not I1 but I2 to hold V2 in the circuit HC, for example. Accordingly, “+2” is set as the first data (a weight coefficient) of the circuit MP. When the first data (a weight coefficient) is “+2” and the signal of a neuron input to the circuit MP is “−1”, the product of the first data (a weight coefficient) and the second data (a value of the signal of a neuron) obtained using Formula (1.1) is “−2”. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “−2” corresponds to the case where the current IOL does not change and the current IOLB increases by I2 after Time T5 in the operation of the circuit MP. By holding VSS in the circuit HCr of the circuit MCr and setting a current amount other than I1 in the circuit MC in the above manner, a positive value other than “+1” can be set as the weight coefficient of the circuit MP.
In this condition, as an example, the operation of the circuit MP in the case where the first data (a weight coefficient) is “−1” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “−1” is considered.
For operation from Time T1 to Time T5, which is similar to the operation from Time T1 to Time T5 in Condition 3, the description of the operation from Time T1 to Time T5 in Condition 3 is referred to.
After Time T5, as “−1” that is the second data (a signal of a neuron (an arithmetic value)) input to the circuit MP, a low-level potential and a high-level potential are input to the wiring WX1L and the wiring X2L, respectively. At this time, the low-level potential is input to the gates of the transistor M3 and the transistor M3r, and the high-level potential is input to the gates of the transistor M4 and the transistor M4r. Accordingly, the transistor M3 and the transistor M3r are turned off and the transistor M4 and the transistor M4r are turned on. That is, by this operation, electrical continuity is not established between the circuit MC and the wiring OL and between the circuit MCr and the wiring OLB, and electrical continuity is established between the circuit MC and the wiring OLB and between the circuit MCr and the wiring OL.
At this time, in
Since the first data (a weight coefficient) is “−1” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “−1” in this condition, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) obtained using Formula (1.1) is “+1”. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “+1” corresponds to the case where the current IOL changes and the current IOLB does not change after Time T5 in the operation of the circuit MP, which agrees with the result of the circuit operation in Condition 2. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “+1” is output as the signal zj(k) from the circuit AFP in
Note that as described in Condition 3, from Time T3 to Time T4 in this condition, the current flowing from the wiring OLB to the circuit MCr may be set to not I1 but I2 to hold V2 in the circuit HCr, for example. Accordingly, “−2” is set as the first data (a weight coefficient) of the circuit MP. When the first data (a weight coefficient) is “−2” and the second data (a value of a signal of a neuron) input to the circuit MP is “−1”, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) obtained using Formula (1.1) is “+2”. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “+2” corresponds to the case where the current IOL does not change and the current IOLB increases by I2 after Time T5 in the operation of the circuit MP. By holding VSS in the circuit HC of the circuit MC and setting a current amount other than I1 in the circuit MCr in the above manner, a negative value other than “−1” can be set as the weight coefficient of the circuit MP.
In this condition, as an example, the operation of the circuit MP is considered using Condition 7 where the first data (a weight coefficient) is “0” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “0”.
For operation from Time T1 to Time T5, which is similar to the operation from Time T1 to Time T5 in Condition 1, the description of the operation from Time T1 to Time T5 in Condition 1 is referred to.
After Time T5, as “0” that is the second data (a signal of a neuron (an arithmetic value)) input to the circuit MP, a low-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L. At this time, the low-level potentials are input to the gates of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r. Accordingly, the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r are turned off. That is, by this operation, electrical continuity between the circuit MC and the wiring OL, between the circuit MCr and the wiring OLB, between the circuit MC and the wiring OLB, and between the circuit MCr and the wiring OL is broken.
Thus, in the circuit MC, a current does not flow between the wiring OL and one of the wiring VE and the wiring VEr regardless of the set amount of current flowing through the transistor M1. Similarly, in the circuit MCr, a current does not flow between the wiring OLB and the other of the wiring VE and the wiring VEr regardless of the set amount of current flowing through the transistor Mir. In other words, the current IOL output from the node outa of the wiring OL and the current IOLB output from the node outb of the wiring OLB do not change before and after Time T5.
In this case, even when electrical continuity is established between the circuit AFP and each of the wiring OL and the wiring OLB by turning on the switch SWO and the switch SWOB and turning off the switch SWI, the switch SWIB, the switch SWL, the switch SWLB, the switch SWH, and the switch SWHB in
Since the first data (a weight coefficient) is “0” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “0” in this condition, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) obtained using Formula (1.1) is “0”. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “0” corresponds to the case where the current IOL and the current IOLB do not change after Time T5 in the operation of the circuit MP, which agrees with the results of the circuit operations in Condition 1 and Condition 4. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “0” is output as the signal zj(k) from the circuit AFP in
In this condition, as an example, the operation of the circuit MP is considered using Condition 8 where the first data (a weight coefficient) is “+1” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “0”.
For operation from Time T1 to Time T5, which is similar to the operation from Time T1 to Time T5 in Condition 2, the description of the operation from Time T1 to Time T5 in Condition 2 is referred to.
After Time T5, as “0” that is the second data (a signal of a neuron (an arithmetic value)) input to the circuit MP, a low-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L. At this time, the low-level potentials are input to the gates of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r. Accordingly, the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r are turned off. That is, by this operation, electrical continuity between the circuit MC and the wiring OL, between the circuit MCr and the wiring OLB, between the circuit MC and the wiring OLB, and between the circuit MCr and the wiring OL is broken regardless of the set amount of current flowing through the transistor M1 and the transistor M1r, as in Condition 7. Consequently, a current does not flow between the wiring OL and one of the wiring VE and the wiring VEr and a current does not flow between the wiring OLB and the other of the wiring VE and the wiring VEr; thus, the current IOL output from the node outa of the wiring OL and the current IOLB output from the node outb of the wiring OLB do not change before and after Time T5.
In this case, even when electrical continuity is established between the circuit AFP and each of the wiring OL and the wiring OLB by turning on the switch SWO and the switch SWOB and turning off the switch SWI, the switch SWIB, the switch SWL, and the switch SWLB in
Since the first data (a weight coefficient) is “+1” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “0” in this condition, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) obtained using Formula (1.1) is “0”. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “0” corresponds to the case where the current IOL and the current IOLB do not change after Time T5 in the operation of the circuit MP, which agrees with the results of the circuit operations in Condition 1, Condition 4, and Condition 7. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “0” is output as the signal zj(k) from the circuit AFP in
In this condition, as an example, the operation of the circuit MP is considered using Condition 9 where the first data (a weight coefficient) is “−1” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “0”.
For operation from Time T1 to Time T5, which is similar to the operation from Time T1 to Time T5 in Condition 3, the description of the operation from Time T1 to Time T5 in Condition 3 is referred to.
After Time T5, as “0” that is the second data (a signal of a neuron (an arithmetic value)) input to the circuit MP, a low-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L. At this time, the low-level potentials are input to the gates of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r. Accordingly, the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r are turned off. That is, by this operation, electrical continuity between the circuit MC and the wiring OL, between the circuit MCr and the wiring OLB, between the circuit MC and the wiring OLB, and between the circuit MCr and the wiring OL is broken regardless of the set amount of current flowing through the transistor M1 and the transistor Mir, as in Condition 7. In this case, a current does not flow between the wiring OL and one of the wiring VE and the wiring VEr and a current does not flow between the wiring OLB and the other of the wiring VE and the wiring VEr; thus, the current IOL output from the node outa of the wiring OL and the current IOLB output from the node outb of the wiring OLB do not change before and after Time T5.
In this case, even when electrical continuity is established between the circuit AFP and each of the wiring OL and the wiring OLB by turning on the switch SWO and the switch SWOB and turning off the switch SWI, the switch SWIB, the switch SWL, the switch SWLB, the switch SWH, and the switch SWHB in
Since the first data (a weight coefficient) is “−1” and the second data (a value of a signal of a neuron (an arithmetic value)) input to the circuit MP is “0” in this condition, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) obtained using Formula (1.1) is “0”. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “0” corresponds to the case where the current IOL and the current IOLB do not change after Time T5 in the operation of the circuit MP, which agrees with the results of the circuit operations in Condition 1, Condition 4, Condition 7, and Condition 8. The result that the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “0” is output as the signal zj(k) from the circuit AFP in
The results of the operation examples under Condition 1 to Condition 9 described above are listed in the following table. Note that in the following table, a high-level potential is denoted by high and a low-level potential is denoted by low.
Here, the case where one circuit MC and one circuit MCr are connected to the wiring OL and the wiring OLB is shown as an example. In the case where a plurality of circuits MC and a plurality of circuits MCr are connected to the wiring OL and the wiring OLB as illustrated in
In the operation of the circuit MP, when calculation using the first data (a weight coefficient) having only two levels “+1” and “−1” and the second data (a value of a signal of a neuron) having only two levels “+1” and “−1” is performed, the circuit MP can perform operation similar to that of an exclusive NOR circuit (coincidence circuit).
In the operation of the circuit MP, when calculation using the first data (a weight coefficient) having only two levels “+1” and “0” and the second data (a value of a signal of a neuron) having only two levels “+1” and “0” is performed, the circuit MP can perform operation similar to that of a logical product circuit.
In this operation example, a potential held in the circuit HC and the circuit HCr included in the circuit MC and the circuit MCr of the circuit MP represents a multilevel value of VSS, V1, or V2, for example; however, a potential representing a binary value or an analog value may be held in the circuit HC and the circuit HCr. For example, in the case where the first data (a weight coefficient) is a “positive analog value”, a high-level analog potential is held at the node n1 of the circuit HC and a low-level potential is held at the node n1r of the circuit HCr. In the case where the first data (a weight coefficient) is a “negative analog value”, a low-level potential is held at the node n1 of the circuit HC and a high-level analog potential is held at the node n1r of the circuit HCr, for example. The amount of the current IOL and the current IOLB becomes an amount corresponding to the analog potential. A potential representing an analog value may also be held in the circuit HC and the circuit HCr in other circuits MP described in this specification and the like without limitation to the operation example of the circuit MP in
Note that this configuration example can be combined with any of the other configuration examples and the like described in this specification as appropriate.
Next, examples of a circuit configuration that can be applied to the circuit MP illustrated in
The circuit MP illustrated in
The circuit MP in
Another example of a circuit configuration that can be applied to the circuit MP illustrated in
Note that in this specification and the like, unless otherwise specified, the transistor M1c and the transistor M1cr in an on state may operate in a saturation region in the end. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in the linear region. However, one embodiment of the present invention is not limited thereto. The transistor M1c and the transistor M1cr may operate in a linear region so that the amplitude value of a voltage to be supplied is decreased. To reduce the amount of current flowing through the transistor M1c and the transistor M1cr, the transistor M1c and the transistor M1cr may operate in a subthreshold region. Alternatively, they may operate around the boundary between the saturation region and the subthreshold region. Note that in the case where the first data (e.g., a weight coefficient here) is an analog value, for example, the transistor M1c and the transistor M1cr may operate in the linear region, the saturation region, and the subthreshold region depending on the cases in accordance with the magnitude of the first data (weight coefficient). Alternatively, the transistor M1c and the transistor M1cr may operate in both the linear region and the saturation region, may operate in both the subthreshold region and the linear region, or may operate in both the saturation region and the subthreshold region.
In the circuit MP in
Note that in the circuit MP in
The description of a portion of the circuit MP in
In the circuit MP in
The circuit MP in
Note that this configuration example can be combined with any of the other configuration examples and the like described in this specification as appropriate.
Next, examples of a circuit configuration that can be applied to the circuit MP illustrated in
The circuit MP illustrated in
Note that in this specification and the like, unless otherwise specified, the transistor M5 and the transistor M5r in an on state may operate in a linear region in the end. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in the linear region. However, one embodiment of the present invention is not limited thereto. The transistor M5 and the transistor M5r may operate in a saturation region or may operate in a subthreshold region. Alternatively, they may operate around the boundary between the saturation region and the subthreshold region. Alternatively, for example, the transistor M5 and the transistor M5r may operate in the linear region, the saturation region, and the subthreshold region depending on the cases. Alternatively, the transistor M5 and the transistor M5r may operate in both the linear region and the saturation region, may operate in both the saturation region and the subthreshold region, or may operate in both the subthreshold region and the linear region.
In the circuit MP in
Note that in the circuit MP in
The description of a portion of the circuit MP in
In the circuit MP in
A current is set in the circuit MC and the circuit MCr by supplying a high-level potential to the wiring WL so that the transistor M2, the transistor M2r, the transistor M5, and the transistor M5r are turned on. After the current is set in the circuit MC and the circuit MCr, in order to hold the set potential in the circuit HC and the circuit HCr, a low-level potential is supplied to the wiring WL so that the transistor M2, the transistor M2r, the transistor M5, and the transistor M5r are turned off.
In the circuit MP described in Configuration example 1 and Configuration example 2, a wiring for transmitting the second data (e.g., a value of a signal of a neuron here) and a wiring for supplying or holding information (e.g., a voltage or a current) corresponding to the first data (e.g., a weight coefficient here) to or in the circuit MP are combined into the wiring WX1L; however, when the circuit MP employs the configuration in
The circuit MP illustrated in
With the configuration illustrated in
Note that the circuits MP illustrated in
Note that this configuration example can be combined with any of the other configuration examples and the like described in this specification as appropriate.
The circuit MP illustrated in
The circuit MC included in the circuit MP in
Note that in this specification and the like, unless otherwise specified, the transistor M1s and the transistor M1sr in an on state may operate in a saturation region in the end, like the transistor M1 and the transistor Mir. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in a saturation region. However, one embodiment of the present invention is not limited thereto. The transistor M1s and the transistor M1sr may operate in a linear region so that the amplitude value of a voltage to be supplied is decreased. To reduce the amount of current flowing through the transistor M1s and the transistor M1sr, the transistor M1s and the transistor M1sr may operate in a subthreshold region. Alternatively, they may operate around the boundary between the saturation region and the subthreshold region. Note that in the case where the first data (a weight coefficient) is an analog value, for example, the transistor M1s and the transistor M1sr may operate in the linear region, the saturation region, and the subthreshold region depending on the cases in accordance with the magnitude of the first data (weight coefficient). Alternatively, the transistor M1s and the transistor M1sr may operate in both the linear region and the saturation region, may operate in both the subthreshold region and the linear region, or may operate in both the saturation region and the subthreshold region.
In this specification and the like, unless otherwise specified, the transistor M2s, the transistor M2sr, the transistor M6, the transistor M6s, the transistor M6r, and the transistor M6sr in an on state may operate in a linear region in the end, like the transistor M2, the transistor M3, the transistor M4, and the like. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in the linear region. However, one embodiment of the present invention is not limited thereto. For example, the transistor M2s, the transistor M2sr, the transistor M6, the transistor M6s, the transistor M6r, and the transistor M6sr in an on state may operate in a saturation region or may operate in a subthreshold region. Alternatively, the transistor M2s, the transistor M2sr, the transistor M6, the transistor M6s, the transistor M6r, and the transistor M6sr may operate around the boundary between the saturation region and the subthreshold region. Alternatively, the transistor M2s, the transistor M2sr, the transistor M6, the transistor M6s, the transistor M6r, and the transistor M6sr may operate in both the linear region and the saturation region, may operate in both the saturation region and the subthreshold region, may operate in both the subthreshold region and the linear region, or may operate in the linear region, the saturation region, and the subthreshold region.
Next, the configuration of the circuit MP in
In the circuit MP in
In the circuit MP in
The wiring S1L functions as a voltage line for supplying a potential for turning on or off the transistor M6 and the transistor M6r, and the wiring S2L functions as a voltage line for supplying a potential for turning on or off the transistor M6s and the transistor M6sr.
In the circuit MP in
For example, by applying the configuration of the circuit MP illustrated in
As described above, the arithmetic circuit 150 using the circuit MP in
The circuit MP included in the semiconductor device of one embodiment of the present invention is not limited to the circuit MP in
For example, the circuit MP illustrated in
Note that in the circuit MP in
In the circuit MP in
By performing operation similar to that of the circuit MP in
Note that this configuration example can be combined with any of the other configuration examples and the like described in this specification as appropriate.
The circuit MP illustrated in
The circuit MC included in the circuit MP in
In this specification and the like, unless otherwise specified, the transistor M1-2b and the transistor M1-3b in an on state may operate in a saturation region in the end, like the transistor M1. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in a saturation region. However, one embodiment of the present invention is not limited thereto. The transistor M1-2b and the transistor M1-3b may operate in a linear region so that the amplitude value of a voltage to be supplied is decreased. To reduce the amount of current flowing through the transistor M1-2b and the transistor M1-3b, the transistor M1-2b and the transistor M1-3b may operate in a subthreshold region. Alternatively, they may operate around the boundary between the saturation region and the subthreshold region. Note that in the case where the first data (e.g., a weight coefficient here) is an analog value, for example, the transistor M1-2b and the transistor M1-3b may operate in the linear region, the saturation region, and the subthreshold region depending on the cases in accordance with the magnitude of the first data (weight coefficient). Alternatively, the transistor M1-2b and the transistor M1-3b may operate in both the linear region and the saturation region, may operate in both the subthreshold region and the linear region, or may operate in both the saturation region and the subthreshold region.
In this specification and the like, unless otherwise specified, the transistor M3-2b, the transistor M4-2b, the transistor M3-3b, and the transistor M4-3b in an on state may operate in a linear region in the end, like the transistor M3 and the transistor M4. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in the linear region. However, one embodiment of the present invention is not limited thereto. For example, the transistor M3-2b, the transistor M4-2b, the transistor M3-3b, and the transistor M4-3b in an on state may operate in a saturation region or may operate in a subthreshold region. Alternatively, the transistor M3-2b, the transistor M4-2b, the transistor M3-3b, and the transistor M4-3b may operate around the boundary between the saturation region and the subthreshold region. Alternatively, the transistor M3-2b, the transistor M4-2b, the transistor M3-3b, and the transistor M4-3b may operate in both the linear region and the saturation region, may operate in both the saturation region and the subthreshold region, may operate in both the subthreshold region and the linear region, or may operate in the linear region, the saturation region, and the subthreshold region.
Next, the configuration of the circuit MP in
In the circuit MC of the circuit MP in
Note that in the circuit MP in
In the circuit MP in
The wiring X1L2b is a wiring for switching the on state and the off state of the transistor M3-2b and the transistor M3-2br; the wiring X2L2b is a wiring for switching the on state and the off state of the transistor M4-2b and the transistor M4-2br; the wiring X1L3b is a wiring for switching the on state and the off state of the transistor M3-3b and the transistor M3-3br; and the wiring X2L3b is a wiring for switching the on state and the off state of the transistor M4-3b and the transistor M4-3br.
When the ratio of the W length to the L length of the transistor M1 is W/L, the ratio of the W length to the L length of the transistor M1-2b is preferably 2×W/L and the ratio of the W length to the L length of the transistor M1-3b is preferably 4×W/L. Since a current flowing between a source and a drain of a transistor is proportional to the ratio of the channel width to the channel length, in the case where the transistor M1, the transistor M1-2b, and the transistor M1-3b have the same structure, structure condition, and the like other than the ratio of the channel width to the channel length, a current flowing through the transistor M1-2b and a current flowing through the transistor M1-3b are respectively about twice and four times as large as the current flowing through the transistor M1. That is, the ratio of the amounts of currents flowing through the transistor M1, the transistor M1-2b, and the transistor M1-3b is approximately 1:2:4. Here, the case is considered where the circuit MC included in the circuit MP in
For example, when the amount of current flowing between the source and the drain of the transistor M1 is Iut, from the above-described ratios of the channel widths to the channel lengths of the transistor M1, the transistor M1-2b, and the transistor M1-3b, the amounts of currents flowing through the transistor M1-2b and the transistor M1-3b are 2Iut and 4Iut, respectively.
Furthermore, the ratio of the W length to the L length of the transistor M1r is preferably equal to the ratio of the W length to the L length of the transistor M1, the ratio of the W length to the L length of the transistor M1-2br is preferably equal to the ratio of the W length to the L length of the transistor M1-2b, and the ratio of the W length to the L length of the transistor M1-3br is preferably equal to the ratio of the W length to the L length of the transistor M1-3b.
Here, the amount of current flowing from the wiring OL to the circuit MC is considered. In this case, the positive first data (a positive weight coefficient) is set in the circuit MP, at least one of the transistor M3, the transistor M3-2b, and the transistor M3-3b is turned on, and at least one of the transistor M4, the transistor M4-2b, and the transistor M4-3b is turned off. At this time, the amount of current flowing from the wiring OL to the circuit MC changes depending on the combination of the on state and the off state of the transistor M3, the transistor M3-2b, and the transistor M3-3b.
For example, when the amount of current flowing between the source and the drain of the transistor M1 is set to Iut, the amount of current flowing through the transistor M1-2b is 2Iut and the amount of current flowing through the transistor M1-3b is 4Iut. Here, when a high-level potential is applied to the wiring WX1L, a low-level potential is applied to the wiring X2L, and a low-level potential is applied to the wiring X1L2b, the wiring X2L2b, the wiring X1L3b, and the wiring X2L3b, the transistor M3 can be turned on and the transistor M3-2b, the transistor M3-3b, the transistor M4, the transistor M4-2b, and the transistor M4-3b can be turned off. At this time, the amount of current flowing from the wiring OL to the circuit MC is Iut. As another example, the amount of current flowing between the source and the drain of the transistor M1 is set to Iut, a high-level potential is applied to the wiring WX1L and the wiring X1L2b, a low-level potential is applied to the wiring X2L and the wiring X2L2b, and furthermore, a low-level potential is applied to the wiring X1L3b and the wiring X2L3b. At this time, the transistor M3 and the transistor M3-2b can be turned on and the transistor M3-3b, the transistor M4, the transistor M4-2b, and the transistor M4-3b can be turned off, so that the amount of current flowing from the wiring OL to the circuit MC is 3Iut. As another example, the amount of current flowing between the source and the drain of the transistor M1 is set to Iut, a high-level potential is applied to the wiring X1L2b and the wiring X1L3b, a low-level potential is applied to the wiring X2L2b and the wiring X2L3b, and furthermore, a low-level potential is applied to the wiring WX1L and the wiring X2L. At this time, the transistor M3-2b and the transistor M3-3b can be turned on and the transistor M3, the transistor M4, the transistor M4-2b, and the transistor M4-3b can be turned off, so that the amount of current flowing from the wiring OL to the circuit MC is 6Iut.
As another example, when the amount of current flowing between the source and the drain of the transistor M1 is set to 2Iut, the amount of current flowing through the transistor M1-2b is 4Iut and the amount of current flowing through the transistor M1-3b is 8Iut. Here, when a high-level potential is applied to the wiring WX1L, a low-level potential is applied to the wiring X2L, and furthermore, a low-level potential is applied to the wiring X1L2b, the wiring X2L2b, the wiring X1L3b, and the wiring X2L3b, the transistor M3 can be turned on and the transistor M3-2b, the transistor M3-3b, the transistor M4, the transistor M4-2b, and the transistor M4-3b can be turned off. At this time, the amount of current flowing from the wiring OL to the circuit MC is 2Iut. As another example, the amount of current flowing between the source and the drain of the transistor M1 is set to 2Iut, a high-level potential is applied to the wiring WX1L and the wiring X1L2b, a low-level potential is applied to the wiring X2L and the wiring X2L2b, and furthermore, a low-level potential is applied to the wiring X1L3b and the wiring X2L3b. At this time, the transistor M3 and the transistor M3-2b can be turned on and the transistor M3-3b, the transistor M4, the transistor M4-2b, and the transistor M4-3b can be turned off, so that the amount of current flowing from the wiring OL to the circuit MC is 6Iu. As another example, the amount of current flowing between the source and the drain of the transistor M1 is set to 2Iut, a high-level potential is applied to the wiring X1L2b and the wiring X1L3b, a low-level potential is applied to the wiring X2L2b and the wiring X2L3b, and furthermore, a low-level potential is applied to the wiring WX1L and the wiring X2L. At this time, the transistor M3-2b and the transistor M3-3b can be turned on and the transistor M3, the transistor M4, the transistor M4-2b, and the transistor M4-3b can be turned off, so that the amount of current flowing from the wiring OL to the circuit MC is 12Iut.
That is, the circuit MP in
Although the amount of current flowing from the wiring OL to the circuit MC is described in the above example, the amount of current flowing from the wiring OLB to the circuit MC can be considered in a similar manner. In this case, the positive first data (a positive weight coefficient) is set in the circuit MP, at least one of the transistor M4, the transistor M4-2b, and the transistor M4-3b is turned on, and at least one of the transistor M3, the transistor M3-2b, and the transistor M3-3b is turned off. At this time, the amount of current flowing from the wiring OLB to the circuit MC changes depending on the combination of the on state and the off state of the transistor M4, the transistor M4-2b, and the transistor M4-3b. In addition, the current flowing from the wiring OLB to the circuit MCr can be considered in a similar manner. In this case, the negative first data (a negative weight coefficient) is set in the circuit MP, at least one of the transistor M3r, the transistor M3-2br, and the transistor M3-3br is turned on, and at least one of the transistor M4r, the transistor M4-2br, and the transistor M4-3br is turned off. At this time, the amount of current flowing from the wiring OLB to the circuit MCr changes depending on the combination of the on state and the off state of the transistor M3r, the transistor M3-2br, and the transistor M3-3br. Furthermore, a current flowing from the wiring OL to the circuit MCr can be considered in a similar manner. In this case, the negative first data (a negative weight coefficient) is set in the circuit MP, at least one of the transistor M4r, the transistor M4-2br, and the transistor M4-3br is turned on, and at least one of the transistor M3r, the transistor M3-2br, and the transistor M3-3br is turned off. At this time, the amount of current flowing from the wiring OL to the circuit MCr changes depending on the combination of the on state and the off state of the transistor M4r, the transistor M4-2br, and the transistor M4-3br.
As described above, the circuit MP in
Given that the first data (a weight coefficient) set in the circuit MP is “+1” (the set amount of current between the source and the drain of the transistor M1 is Iut and the set amount of current between the source and the drain of the transistor M1r is 0. Note that the potential of the node n1 of the circuit HC is V1 and the potential of the node n1r of the circuit HCr is VSS), the following table shows the changes in current amounts of the current IOL flowing from the wiring OL to the circuit MC or the circuit MCr and the current IOLB flowing from the wiring OLB to the circuit MC or the circuit MCr when the potentials of the wiring WX1L, the wiring X2L, the wiring X1L2b, the wiring X2L2b, the wiring X1L3b, and the wiring X2L3b, which correspond to the second data (a value of a signal of a neuron), are input to the circuit MP. Note that in the following table, a high-level potential is denoted by high and a low-level potential is denoted by low.
Given that the first data (a weight coefficient) set in the circuit MP is “−1” (the set amount of current between the source and the drain of the transistor M1 is 0 and the set amount of current between the source and the drain of the transistor M1r is Iut. Note that the potential of the node n1 of the circuit HC is VSS and the potential of the node n1r of the circuit HCr is V1), the following table shows the changes in current amounts of the current IOL flowing from the wiring OL to the circuit MC or the circuit MCr and the current IOLB flowing from the wiring OLB to the circuit MC or the circuit MCr when the potentials of the wiring WX1L, the wiring X2L, the wiring X1L2b, the wiring X2L2b, the wiring X1L3b, and the wiring X2L3b, which correspond to the second data (a value of a signal of a neuron), are input to the circuit MP. Note that in the following table, a high-level potential is denoted by high and a low-level potential is denoted by low.
When the amount of current flowing between the source and the drain of the transistor M1 is 0, the potential of the node n1 is VSS, for example. In this case, the amount of current flowing between the sources and the drains of the transistor M1-2b and the transistor M1-3b as well as the transistor M1 can also be 0. Thus, a current does not flow from the wiring OL or the wiring OLB to the circuit MC regardless of the on state or the off state of the transistor M3, the transistor M3-2b, the transistor M3-3b, the transistor M4, the transistor M4-2b, and the transistor M4-3b.
As described above, by setting each of the wiring WX1L, the wiring X2L, the wiring X1L2b, the wiring X2L2b, the wiring X1L3b, and the wiring X2L3b to a low-level potential or a high-level potential, the circuit MIP in
The circuit MP included in the semiconductor device of one embodiment of the present invention is not limited to the circuit MP in
For example, the circuit MP illustrated in
In the circuit MC, the electrical connection configuration around the transistor M1-2b, the transistor M3-2b, the transistor M4-2b, and the circuit HC-2b is similar to the electrical connection configuration around the transistor M1, the transistor M3, the transistor M4, and the circuit HC. In addition, the electrical connection configuration around the transistor M1-3b, the transistor M3-3b, the transistor M4-3b, and the circuit HC-3b is similar to the electrical connection configuration around the transistor M1, the transistor M3, the transistor M4, and the circuit HC. In the circuit MCr, the electrical connection configuration around the transistor M1-2br, the transistor M3-2br, the transistor M4-2br, and the circuit HC-2br is similar to the electrical connection configuration around the transistor M1r, the transistor M3r, the transistor M4r, and the circuit HCr. In addition, the electrical connection configuration around the transistor M1-3br, the transistor M3-3br, the transistor M4-3br, and the circuit HC-3br is similar to the electrical connection configuration around the transistor M1r, the transistor M3r, the transistor M4r, and the circuit HCr.
Furthermore, the circuit HC-2b is electrically connected to a wiring WL2b, the circuit HC-3b is electrically connected to a wiring WL3b, the circuit HC-2br is electrically connected to the wiring WL2b, and the circuit HC-3br is electrically connected to the wiring WL3b.
The circuit MP in
Almost equal potentials are written to the circuit HC, the circuit HC-2b, and the circuit HC-3b, and thus the wiring WL, the wiring WL2b, and the wiring WL3b may be combined into one wiring (not illustrated).
Alternatively, for example, in the case where the ratios of the W lengths to the L lengths of the transistor M1, the transistor M1-2b, and the transistor M1-3b are set to be equal to each other and the amount of current flowing between the source and the drain of the transistor M1 is set to I, the operation can be similar to that of the circuit MP in
As a circuit configuration that is changed from that of the circuit MP in
In this specification and the like, unless otherwise specified, the transistor M2-2b, the transistor M2-3b, the transistor M2-2br, and the transistor M2-3br may operate in the linear region in the end, like the transistor M2 and the transistor M2r. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in the linear region. However, one embodiment of the present invention is not limited thereto. For example, the transistor M2-2b, the transistor M2-3b, the transistor M2-2br, and the transistor M2-3br in an on state may operate in a saturation region or may operate in a subthreshold region. Alternatively, the transistor M2-2b, the transistor M2-3b, the transistor M2-2br, and the transistor M2-3br may operate around the boundary between the saturation region and the subthreshold region. Alternatively, the transistor M2-2b, the transistor M2-3b, the transistor M2-2br, and the transistor M2-3br may operate in both the linear region and the saturation region, may operate in both the saturation region and the subthreshold region, may operate in both the subthreshold region and the linear region, or may operate in the linear region, the saturation region, and the subthreshold region.
In the circuit MC, a first terminal of the transistor M2-2b is electrically connected to a first terminal of the transistor M2-3b, the first terminal of the transistor M2, the gate of the transistor M1, the gate of the transistor M1-2b, the gate of the transistor M1-3b, and the first terminal of the capacitor C1. A second terminal of the transistor M2-2b is electrically connected to the second terminal of the transistor M1-2b, the first terminal of the transistor M3-2b, and the first terminal of the transistor M4-2b. A second terminal of the transistor M2-3b is electrically connected to the second terminal of the transistor M1-3b, the first terminal of the transistor M3-3b, and the first terminal of the transistor M4-3b. A gate of the transistor M2-2b and a gate of the transistor M2-3b are electrically connected to the wiring WL.
Similarly, in the circuit MCr, a first terminal of the transistor M2-2br is electrically connected to a first terminal of the transistor M2-3br, a first terminal of the transistor M2r, the gate of the transistor M1r, a gate of the transistor M1-2br, a gate of the transistor M1-3br, and the first terminal of the capacitor C1. A second terminal of the transistor M2-2br is electrically connected to a second terminal of the transistor M1-2br, a first terminal of the transistor M3-2br, and a first terminal of the transistor M4-2br. A second terminal of the transistor M2-3br is electrically connected to the second terminal of the transistor M1-3br, a first terminal of the transistor M3-3br, and a first terminal of the transistor M4-3br. A gate of the transistor M2-2br and a gate of the transistor M2-3br are electrically connected to the wiring WL.
The wiring WX1L2b and the wiring WX1L3b illustrated in
To set currents flowing through the transistor M1, the transistor M1-2b, the transistor M1-3b, the transistor M1r, the transistor M1-2br, and the transistor M1-3br, a high-level potential is input to the wiring WL, the wiring WX1L, the wiring WX1L2b, and the wiring WX1L3b so that the transistor M2, the transistor M2-2b, the transistor M2-3b, the transistor M3, the transistor M3-2b, and the transistor M3-3b are turned on. Furthermore, a low-level potential is input to the wiring X2L, the wiring X2L2b, and the wiring X2L3b so that the transistor M4, the transistor M4-2b, the transistor M4-3b, the transistor M4r, the transistor M4-2br, and the transistor M4-3br are turned off.
At this time, the total sum of the currents to be set in the transistor M1, the transistor M1-2b, and the transistor M1-3b, e.g., 7Iut, is supplied from the wiring OL to the circuit MC, so that the node n1 of the circuit HC has a predetermined potential. Here, a low-level potential is input to the wiring WL so that the transistor M2 is turned off, whereby the predetermined potential is held at the node n1 of the circuit HC. Accordingly, currents of Iut, 2Iut, and 4Iut are set to flow between the sources and the drains of the transistor M1, the transistor M1-2b, and the transistor M1-3b, respectively.
Similarly, the total sum of the currents to be set in the transistor M1r, the transistor M1-2br, and the transistor M1-3br, e.g., 7Iut, is supplied from the wiring OLB to the circuit MCr, so that the node n1r of the circuit HCr has a predetermined potential. Then, a low-level potential is input to the wiring WL so that the predetermined potential is held at the node n1r of the circuit HCr, whereby currents of Iut, 2Iut, and 4Iut are set to flow between the sources and the drains of the transistor M1r, the transistor M1-2br, and the transistor M1-3br, respectively.
The circuit MP having the configuration in
As another modification example of the circuit MP in
The circuit HCS is electrically connected to the wiring OL and the wiring OLB, for example. The circuit HCS has a function of receiving information (a potential, a current, or the like) input from one or both of the wiring OL and the wiring OLB and holding a potential corresponding to the information. In addition, the circuit HCS is electrically connected to the gates of the transistor M1, the transistor M1-2b, and the transistor M1-3b. The circuit HCS has a function of applying the held potential to the gates of the transistor M1, the transistor M1-2b, and the transistor M1-3b. Thus, a source-drain current based on the potential supplied from the circuit HCS and the ratio of the W length to the L length flows through each of the transistor M1, the transistor M1-2b, and the transistor M1-3b. Note that the circuit HCSr has functions similar to those of the circuit HCS, and a source-drain current based on the potential supplied from the circuit HCSr and the ratio of the W length to the L length flows through each of the transistor M1r, the transistor M1-2br, and the transistor M1-3br.
Note that in the case where the circuit HCS and the circuit HCSr each have a configuration including an SRAM, the SRAM holds one of a high-level potential and a low-level potential; thus, the first data (a weight coefficient) set in the circuit MP is limited to having two levels (e.g., a combination of “−1” and “+1”) or three levels (e.g., a combination of “−1”, “0”, and “+1”), for example. For example, when the first data (a weight coefficient) set in the circuit MP is “+1”, a high-level potential is held in the circuit HCS and a low-level potential is held in the circuit HCSr. As another example, when the first data (a weight coefficient) set in the circuit MP is “−1”, a low-level potential is held in the circuit HCS and a high-level potential is held in the circuit HCSr. As another example, when the first data (a weight coefficient) set in the circuit MP is “0”, a low-level potential is held in the circuit HCS and a low-level potential is held in the circuit HCSr.
The circuit HCS includes a transistor M7, a transistor M7s, and an inverter loop circuit IVR. The inverter loop circuit IVR includes an inverter circuit IV1 and an inverter circuit IV2.
In this specification and the like, unless otherwise specified, the transistor M7 and the transistor M7s in an on state may operate in a linear region in the end. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in the linear region. However, one embodiment of the present invention is not limited thereto. For example, the transistor M7 and the transistor M7s in an on state may operate in a saturation region or may operate in a subthreshold region. Alternatively, the transistor M7 and the transistor M7s may operate around the boundary between the saturation region and the subthreshold region. Alternatively, the transistor M7 and the transistor M7s may operate in both the linear region and the saturation region, may operate in both the saturation region and the subthreshold region, may operate in both the subthreshold region and the linear region, or may operate in the linear region, the saturation region, and the subthreshold region.
The inverter circuit IV1 and the inverter circuit IV2 each have a function of outputting, from its output terminal, an inverted signal of an input signal that is input to an input terminal. Thus, an inverter circuit can be used as each of the inverter circuit IV1 and the inverter circuit IV2, for example.
Alternatively, the inverter circuit IV1 and the inverter circuit IV2 can each be a NAND circuit, a NOR circuit, an XOR circuit, or a circuit in which these are combined, for example. Specifically, in the case where the inverter circuit is replaced with a NAND circuit, a high-level potential is input to one of two input terminals of the NAND circuit as a fixed potential, so that the NAND circuit can function as an inverter circuit. In the case where the inverter circuit is replaced with a NOR circuit, a low-level potential is input to one of two input terminals of the NOR circuit as a fixed potential, so that the NOR circuit can function as an inverter circuit. In the case where the inverter circuit is replaced with an XOR circuit, a high-level potential is input to one of two input terminals of the XOR circuit as a fixed potential, so that the XOR circuit can function as an inverter circuit.
As described above, an inverter circuit described in this specification and the like can be replaced with a logic circuit such as a NAND circuit, a NOR circuit, an XOR circuit, or a circuit in which these are combined. Thus, in this specification and the like, the term “inverter circuit” can be referred to as a “logic circuit”.
A first terminal of the transistor M7 is electrically connected to the wiring OL; a second terminal of the transistor M7 is electrically connected to the input terminal of the inverter circuit IV1, the output terminal of the inverter circuit IV2, the gate of the transistor M1, the gate of the transistor M1-2b, and the gate of the transistor M1-3b; and agate of the transistor M7 is electrically connected to the wiring WL. A first terminal of the transistor M7s is electrically connected to the wiring OLB, a second terminal of the transistor M7s is electrically connected to the output terminal of the inverter circuit IV1 and the input terminal of the inverter circuit IV2, and a gate of the transistor M7s is electrically connected to the wiring WL. A wiring VEH is electrically connected to high power supply potential input terminals of the inverter circuit IV1 and the inverter circuit IV2, and the wiring VE is electrically connected to low power supply potential input terminals of the inverter circuit IV1 and the inverter circuit IV2.
The wiring VEH functions as a wiring for supplying a constant voltage, for example. The constant voltage can be, for example, VDD that is a high-level potential, or VDDL that is a potential higher than the low-level potential VSS and lower than VDD. The constant voltage is preferably set as appropriate in accordance with the configuration of the circuit MP. Alternatively, the wiring VAL may be supplied with not a constant voltage but a pulse signal, for example. Note that in the description of this configuration example, the wiring VEH functions as a wiring for supplying the potential VDD.
Note that in the circuit MP in
When information (e.g., a potential or a current) is written to the circuit HCS and the circuit HCSr, a high-level potential is applied to the wiring WL so that the transistor M7, the transistor M7s, the transistor M7r, and the transistor M7sr are turned on. After that, one of a high-level potential and a low-level potential is input to the wiring OL and the other of the high-level potential and the low-level potential is input to the wiring OLB. It is particularly preferable that the high-level potential be almost equal to a potential supplied from the wiring VEH. Here, the high-level potential is described as the potential VDDL and the low-level potential is described as the potential VSS, for example.
After one of VDDL and VSS is written to the circuit HCS and the other of VDDL and VSS is written to the circuit HCSr, a low-level potential is applied to the wiring WL so that the transistor M7, the transistor M7s, the transistor M7r, and the transistor M7sr are turned off. Accordingly, the circuit HCS can hold one of VDDL and VSS in the inverter loop circuit IVR and the circuit HCSr can hold the other of VDDL and VSS in an inverter loop circuit IVRr.
After a predetermined potential is held in each of the circuit HCS and the circuit HCSr, as in the circuit MP in
The circuit MP in
The circuit MP having the configuration in
The circuit MP in
The circuit MP in
Specifically, the wiring OL of the circuit MP in
In contrast, the wiring OL of the circuit MP in
The circuit MP having the configuration in
In the case where the configuration of the circuit MP in
The circuit HCS includes a transistor M8 and a capacitor C2.
In this specification and the like, unless otherwise specified, the transistor M8 in an on state may operate in a linear region in the end. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in the linear region. However, one embodiment of the present invention is not limited thereto. For example, the transistor M8 in an on state may operate in a saturation region or may operate in a subthreshold region. Alternatively, the transistor M8 may operate around the boundary between the saturation region and the subthreshold region. Alternatively, the transistor M8 may operate in both the linear region and the saturation region, may operate in both the saturation region and the subthreshold region, may operate in both the subthreshold region and the linear region, or may operate in the linear region, the saturation region, and the subthreshold region.
A first terminal of the transistor M8 is electrically connected to the wiring IL; a second terminal of the transistor M8 is electrically connected to a first terminal of the capacitor C2, the gate of the transistor M1, the gate of the transistor M1-2b, and the gate of the transistor M1-3b; and a gate of the transistor M8 is electrically connected to the wiring WL. A second terminal of the capacitor C2 is electrically connected to the wiring VE.
Note that in the circuit HCS illustrated in
In the circuit MP in
Note that in the case where the circuit HCS and the circuit HCSr each have a configuration including a NOSRAM, one of a high-level potential and a low-level potential can be held in each of the circuit HCS and the circuit HCSr. Thus, the first data (a weight coefficient) set in the circuit MP is limited to having two levels (e.g., “−1” and “+1”) or three levels (e.g., “−1”, “0”, and “+1”), for example. For example, when the first data (a weight coefficient) set in the circuit MP is “+1”, a high-level potential is held in the circuit HCS and a low-level potential is held in the circuit HCSr. As another example, when the first data (a weight coefficient) set in the circuit MP is “−1”, a low-level potential is held in the circuit HCS and a high-level potential is held in the circuit HCSr. As another example, when the first data (a weight coefficient) set in the circuit MP is “0”, a low-level potential is held in the circuit HCS and a low-level potential is held in the circuit HCSr. Note that instead of a binary value (a digital value) of a high-level potential or a low-level potential, a ternary or higher-level digital value or an analog value may be held in the circuit HCS and the circuit HCSr.
When information (a potential here) is written to the circuit HCS and the circuit HCSr, a high-level potential is applied to the wiring WL so that the transistor M8 and the transistor M8r are turned on. After that, one of a high-level potential and a low-level potential is input to the wiring IL and the other of the high-level potential and the low-level potential is input to the wiring ILB. Here, the high-level potential is described as the potential VDDL and the low-level potential is described as the potential VSS, for example.
After one of VDDL and VSS is written to the first terminal of the capacitor C2 of the circuit HCS and the other of VDDL and VSS is written to a first terminal of a capacitor C2r of the circuit HCSr, a low-level potential is applied to the wiring WL so that the transistor M8 and the transistor M8r are turned off. Accordingly, the circuit HCS can hold one of VDDL and VSS at the node n2 and the circuit HCSr can hold the other of VDDL and VSS at the node n2r.
After a predetermined potential is held in each of the circuit HCS and the circuit HCSr, as in the circuit MP in
The circuit MP having the configuration in
Although the circuits MP illustrated in
The circuit MP illustrated in
The circuit HCS, the circuit HCS-2b, the circuit HCS-3b, the circuit HCSr, the circuit HCS-2br, and the circuit HCS-3br may all have a configuration including an SRAM or a configuration including a NOSRAM, for example. Alternatively, one or more circuits selected from the circuit HCS, the circuit HCS-2b, the circuit HCS-3b, the circuit HCSr, the circuit HCS-2br, and the circuit HCS-3br may have a configuration including an SRAM and the other circuits may have a configuration including a NOSRAM.
Although the circuit HCS, the circuit HCS-2b, the circuit HCS-3b, the circuit HCSr, the circuit HCS-2br, and the circuit HCS-3br included in the circuit MP in
Note that this configuration example can be combined with any of the other configuration examples and the like described in this specification as appropriate.
When the ratio of the W length to the L length of the transistor M1 included in the circuit MP in
The circuit HCS is electrically connected to the wiring OL and the gate of the transistor M1, the circuit HCS-2b is electrically connected to the wiring OL and the gate of the transistor M1-2b, and the circuit HCS-3b is electrically connected to the wiring OL and the gate of the transistor M1-3b.
The first terminals of the transistor M1, the transistor M1-2b, and the transistor M1-3b are electrically connected to the wiring VE, and the first terminal of the transistor M3 is electrically connected to the first terminal of the transistor M4 and the second terminals of the transistor M1, the transistor M1-2b, and the transistor M1-3b. The second terminal of the transistor M3 is electrically connected to the wiring OL, and the gate of the transistor M3 is electrically connected to the wiring X1L. The second terminal of the transistor M4 is electrically connected to the wiring OLB, and the gate of the transistor M4 is electrically connected to the wiring X2L.
In the circuit MP in
When a low-level potential, e.g., VSS, is held in the circuit HCSr, the circuit HCS-2br, and the circuit HCS-3br included in the circuit MCr, the transistor M1r, the transistor M1-2br, and the transistor M1-3br can be turned off. Here, when a high-level potential or a low-level potential is held in each of the circuit HCS, the circuit HCS-2b, and the circuit HCS-3b included in the circuit MC, the amounts of currents flowing through the transistor M1, the transistor M1-2b, and the transistor M1-3b are determined in accordance with the potentials held in the circuit HCS, the circuit HCS-2b, and the circuit HCS-3b, respectively. After that, the currents can flow from the wiring OL to the wiring VE through the circuit MC by turning on the transistor M3 and turning off the transistor M4. Alternatively, the currents can flow from the wiring OLB to the wiring VE through the circuit MC by turning off the transistor M3 and turning on the transistor M4.
When a low-level potential, e.g., VSS, is held in the circuit HCS, the circuit HCS-2b, and the circuit HCS-3b included in the circuit MC, the transistor M1, the transistor M1-2b, and the transistor M1-3b can be turned off. Here, when a high-level potential or a low-level potential is held in each of the circuit HCSr, the circuit HCS-2br, and the circuit HCS-3br included in the circuit MCr, the amounts of currents flowing through the transistor M1r, the transistor M1-2br, and the transistor M1-3br are determined in accordance with the potentials held in the circuit HCSr, the circuit HCS-2br, and the circuit HCS-3br, respectively. After that, the currents can flow from the wiring OLB to the wiring VEr through the circuit MCr by turning on the transistor M3r and turning off the transistor M4r. Alternatively, the currents can flow from the wiring OL to the wiring VEr through the circuit MCr by turning off the transistor M3r and turning on the transistor M4r.
In the case where the positive first data (e.g., a weight coefficient here) is held in the circuit MP in
As a specific example different from that in
The circuit MP in
In this specification and the like, unless otherwise specified, the transistor Mix, the transistor M1x-2b, and the transistor M1x-3b in an on state may operate in a saturation region in the end, like the transistor M1. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in a saturation region. However, one embodiment of the present invention is not limited thereto. The transistor Mix, the transistor M1x-2b, and the transistor M1x-3b may operate in a linear region to reduce the amplitude value of a voltage to be supplied. To reduce the amount of current flowing through the transistor Mix, the transistor Mix-2b, and the transistor Mix-3b, the transistor Mix, the transistor Mix-2b, and the transistor Mix-3b may operate in a subthreshold region. Alternatively, the transistor Mix, the transistor Mix-2b, and the transistor Mix-3b may operate around the boundary between the saturation region and the subthreshold region. Note that in the case where the first data (a weight coefficient) is an analog value, for example, the transistor Mix, the transistor Mix-2b, and the transistor Mix-3b may operate in the linear region, the saturation region, and the subthreshold region depending on the cases in accordance with the magnitude of the first data (weight coefficient). Alternatively, the transistor Mix, the transistor Mix-2b, and the transistor Mix-3b may operate in both the linear region and the saturation region, may operate in both the subthreshold region and the linear region, or may operate in both the saturation region and the subthreshold region.
In this specification and the like, unless otherwise specified, the transistor M3-2x and the transistor M4-2x in an on state may operate in a saturation region in the end, like the transistor M3 and the transistor M4. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in the linear region. However, one embodiment of the present invention is not limited thereto. For example, the transistor M3-2x and the transistor M4-2x in an on state may operate in a saturation region or may operate in a subthreshold region. Alternatively, the transistor M3-2x and the transistor M4-2x may operate around the boundary between the saturation region and the subthreshold region. Alternatively, the transistor M3-2x and the transistor M4-2x may operate in both the linear region and the saturation region, may operate in both the saturation region and the subthreshold region, may operate in both the subthreshold region and the linear region, or may operate in the linear region, the saturation region, and the subthreshold region.
The ratio of the W length to the L length of the transistor Mix included in the circuit MP in
First terminals of the transistor Mix, the transistor M1x-2b, and the transistor M1x-3b are electrically connected to the wiring VE. Agate of the transistor Mix is electrically connected to the circuit HCS, a gate of the transistor M1x-2b is electrically connected to the circuit HCS-2b, and a gate of the transistor M1x-3b is electrically connected to the circuit HCS-3b. A first terminal of the transistor M3-2x is electrically connected to a first terminal of the transistor M4-2x and second terminals of the transistor Mix, the transistor M1x-2b, and the transistor M1x-3b. A second terminal of the transistor M3-2x is electrically connected to the wiring OL, and a gate of the transistor M3-2x is electrically connected to a wiring X1L2x. A second terminal of the transistor M4-2x is electrically connected to the wiring OLB, and a gate of the transistor M4-2x is electrically connected to a wiring X2L2x.
Note that in the circuit MP in
The wiring X1L2x is a wiring for switching the on state and the off state of the transistor M3-2x and the transistor M3-2xr, and the wiring X2L2x is a wiring for switching the on state and the off state of the transistors M4-2x and M4-2xr.
When a high-level potential, e.g., VDDL, is held in the circuit HCS, the current amount of ut is supplied between the source and the drain of the transistor M1. Here, when a high-level potential, e.g., VDDL, is held in the circuit HCS-2b, the amount of current flowing between the source and the drain of the transistor M1-2b is 2Iut because the ratio of the W length to the L length of the transistor M1-2b is twice as high as the ratio of the W length to the L length of the transistor M1. When a high-level potential, e.g., VDDL, is held in the circuit HCS-3b, the amount of current flowing between the source and the drain of the transistor M1-3b is 4Iut because the ratio of the W length to the L length of the transistor M1-3b is four times as high as the ratio of the W length to the L length of the transistor M1.
That is, a current flowing from the electrical connection point of the first terminal of the transistor M3 and the first terminal of the transistor M4 to the wiring VE through the circuit MC change from 0 to 7Iut in steps of ut, in accordance with the potentials held in the circuit HCS, the circuit HCS-2b, and the circuit HCS-3b. Here, the amount of the current is referred to as IX1.
When a high-level potential, e.g., VDDL, is held in the circuit HCS, the current amount of 2Iut is supplied between the source and the drain of the transistor Mix because the ratio of the W length to the L length of the transistor Mix is twice as high as the ratio of the W length to the L length of the transistor M1. When a high-level potential, e.g., VDDL, is held in the circuit HCS-2b, the amount of current flowing between the source and the drain of the transistor M1x-2b is 4Iut because the ratio of the W length to the L length of the transistor M1x-2b is four times as high as the ratio of the W length to the L length of the transistor M1. When a high-level potential, e.g., VDDL, is held in the circuit HCS-3b, the amount of current flowing between the source and the drain of the transistor M1x-3b is 8Iut because the ratio of the W length to the L length of the transistor M1x-3b is eight times as high as the ratio of the W length to the L length of the transistor M1.
That is, currents flowing from the electrical connection point of the first terminal of the transistor M3-2x and the first terminal of the transistor M4-2x to the wiring VE through the circuit MC change from 0 to 14Iut in steps of 2Iut, in accordance with the potentials held in the circuit HCS, the circuit HCS-2b, and the circuit HCS-3b. Here, the amount of the current is referred to as IX2. That is, IX2=2IX1 is satisfied.
Here, the case is considered where a high-level potential or a low-level potential is supplied to each of the wiring X1L, the wiring X2L, the wiring X1L2x, and the wiring X2L2x when the positive first data (a weight coefficient) is set in the circuit MP in
When a low-level potential is supplied to the wiring X1L, the wiring X2L, the wiring X1L2x, and the wiring X2L2x, the transistor M3, the transistor M3-2x, the transistor M4, and the transistor M4-2x are turned off in the circuit MC. At this time, a current does not flow from the wiring OL to the wiring VE through the circuit MC.
When a high-level potential is supplied to the wiring X1L and a low-level potential is supplied to the wiring X2L, the wiring X1L2x, and the wiring X2L2x, the transistor M3 is turned on and the transistor M3-2x, the transistor M4, and the transistor M4-2x are turned off in the circuit MC. At this time, the current amount of IX1 is supplied from the wiring OL to the wiring VE through the circuit MC.
When a high-level potential is supplied to the wiring X2L and a low-level potential is supplied to the wiring X1L, the wiring X1L2x, and the wiring X2L2x, the transistor M4 is turned on and the transistor M3, the transistor M3-2x, and the transistor M4-2x are turned off in the circuit MC. At this time, the current amount of IX1 is supplied from the wiring OLB to the wiring VE through the circuit MC.
When a high-level potential is supplied to the wiring X1L2x and a low-level potential is supplied to the wiring X1L, the wiring X2L, and the wiring X2L2x, the transistor M3-2x is turned on and the transistor M3, the transistor M4, and the transistor M4-2x are turned off in the circuit MC. At this time, the current amount of IX2=2IX1 is supplied from the wiring OL to the wiring VE through the circuit MC.
When a high-level potential is supplied to the wiring X2L2x and a low-level potential is supplied to each of the wiring X1L, the wiring X1L2x, and the wiring X2L, the transistor M4-2x is turned on and the transistor M3, the transistor M4, and the transistor M3-2x are turned off in the circuit MC. At this time, the current amount of IX2=2IX1 is supplied from the wiring OLB to the wiring VE through the circuit MC.
When a high-level potential is supplied to the wiring X1L and the wiring X1L2x and a low-level potential is supplied to the wiring X2L and the wiring X2L2x, the transistor M3 and the transistor M3-2x are turned on and the transistor M4 and the transistor M4-2x are turned off in the circuit MC. At this time, the current amount of IX1+IX2=3IX1 is supplied from the wiring OL to the wiring VE through the circuit MC.
Similarly, when a high-level potential is supplied to the wiring X2L and the wiring X2L2x and a low-level potential is supplied to the wiring X1L and the wiring X1L2x, the transistor M4 and the transistor M4-2x are turned on and the transistor M3 and the transistor M3-2x are turned off in the circuit MC. At this time, the current amount of IX1+IX2=3IX1 is supplied from the wiring OLB to the wiring VE through the circuit MC.
As described above, the circuit MC included in the circuit MP in
Although an example in which the positive first data (a weight coefficient) is set in the circuit MP in
In the case where the first data (a weight coefficient) of 0 is set in the circuit MP in
As described above, in the circuit MP in
Note that this configuration example can be combined with any of the other configuration examples and the like described in this specification as appropriate.
Configuration example 1 to Configuration example 6 each describe the circuit MP that can calculate a product of the first data (e.g., a weight coefficient here) that is a “positive multilevel value”, “0”, or a “negative multilevel value” held in the circuit MP and the second data (e.g., a value of a signal of a neuron here); meanwhile, this configuration example describes the circuit MP that can calculate a product of the first data (a weight coefficient) that is a “positive multilevel value”, “0”, or a “negative multilevel value” and the second data (a value of a signal of a neuron) having two levels “+1” and “0”, for example.
The circuit MP illustrated in
The first data (a weight coefficient) set in the circuit MP in
The second data (a value of a signal of a neuron) input to the circuit MP in
For the operation of the circuit MP in
In the case where the first data (a weight coefficient) and the second data (a value of a signal of a neuron) to be input are defined as described above in the circuit MP in
As shown in the above table, the circuit MP in
Although a current set in each of the circuit HC of the circuit MC and the circuit HCr of the circuit MCr in the circuit MP has a multilevel value in this operation example, the set current may have an analog value. For example, in the case where the first data (a weight coefficient) is a “positive analog value”, a current having an analog value is set at the node n1 of the circuit HC, a potential corresponding to the current is held at the node n1, and a low-level potential is held at the node n1r of the circuit HCr. In the case where the first data (a weight coefficient) is a “negative analog value”, for example, a low-level potential is held at the node n1 of the circuit HC, a current having an analog value is set at the node n1r of the circuit HCr, and a potential corresponding to the current is held at the node n1r. The amount of the current IOL and the current IOLB becomes an amount corresponding to the analog potential.
Note that this configuration example can be combined with any of the other configuration examples and the like described in this specification as appropriate.
Next, a configuration example of the circuit MP in the case where a transistor included in the circuit ILD and a transistor included in the circuit MP have the same polarity is described.
Described here is the configuration example of the circuit MP in which all of the included transistors are n-channel transistors in the case where the constant current source circuit ISC1 (the constant current source circuit ISC2 or the constant current source circuit ISC3) included in the current source circuit ISC of the circuit ILD has a configuration including the n-channel transistor in
The circuit MP illustrated in
In the circuit MP in
In this specification and the like, unless otherwise specified, the transistor M9 in an on state may operate in a linear region in the end. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in the linear region. However, one embodiment of the present invention is not limited thereto. For example, the transistor M9 in an on state may operate in a saturation region or may operate in a subthreshold region. Alternatively, the transistor M9 may operate in both the linear region and the saturation region, may operate in both the saturation region and the subthreshold region, may operate in both the subthreshold region and the linear region, or may operate in the linear region, the saturation region, and the subthreshold region.
The gate of the transistor M1 is electrically connected to a first terminal of the transistor M9 and a first terminal of the capacitor C3. A second terminal of the transistor M9 is electrically connected to the wiring VE. The back gate of the transistor M1 is electrically connected to the second terminal of the transistor M1, a second terminal of the capacitor C3, the first terminal of the transistor M3, and the first terminal of the transistor M4.
When the back gate of the transistor M1 and the second terminal of the transistor M1 are electrically connected to each other and a high-level potential is supplied to the first terminal of the transistor M1, the transistor M1 can increase the threshold voltage of the transistor M1 in some cases. Note that the semiconductor device of one embodiment of the present invention is not limited thereto; for example, the circuit MP in
In the circuit HC illustrated in
In the circuit MP in
In the circuit MP in
When a current flowing between the source and the drain of the transistor M1 is set in the circuit MC in
The wiring VA functions as a wiring for supplying a constant voltage, for example. It is particularly preferable that the constant voltage be a ground potential, a low-level potential, or a potential higher than VSS and lower than VDD, which is the high-level potential supplied from the wiring VE. Here, the constant voltage supplied from the wiring VA is denoted as VM, and the potential VM is a ground potential, a low-level potential, or a potential higher than VSS and lower than VDD, which is the high-level potential supplied from the wiring VE.
When the potential of the second terminal of the transistor M1 is denoted as VS in the circuit MP in
Note that “normally-on characteristics” means a state where a channel exists without application of a voltage to a gate of a transistor and a current flows through the transistor.
In the circuit MP in
Next, a configuration example of the circuit MP, which is different from those in
The circuit MP illustrated in
The circuit MC included in the circuit MP in
In this specification and the like, unless otherwise specified, the transistor M1-2b in an on state may operate in a saturation region in the end, like the transistor M1. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in a saturation region. However, one embodiment of the present invention is not limited thereto. The transistor M1-2b may operate in a linear region so that the amplitude value of a voltage to be supplied is decreased. To reduce the amount of current flowing through the transistor M1-2b, the transistor M1-2b may operate in a subthreshold region. Alternatively, the transistor M1-2b may operate around the boundary between the saturation region and the subthreshold region. Note that in the case where the first data (a weight coefficient) is an analog value, for example, the transistor M1-2b may operate in the linear region, the saturation region, and the subthreshold region depending on the cases in accordance with the magnitude of the first data (weight coefficient). Alternatively, the transistor M1-2b may operate in both the linear region and the saturation region, may operate in both the subthreshold region and the linear region, or may operate in both the saturation region and the subthreshold region.
In this specification and the like, unless otherwise specified, the transistor M3-2b, the transistor M4-2b, and the transistor M10 in an on state may operate in a saturation region in the end. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in the linear region. However, one embodiment of the present invention is not limited thereto. For example, the transistor M3-2b, the transistor M4-2b, and the transistor M10 in an on state may operate in a saturation region or may operate in a subthreshold region. Alternatively, they may operate around the boundary between the saturation region and the subthreshold region. Alternatively, the transistor M3-2b, the transistor M4-2b, and the transistor M10 may operate in both the linear region and the saturation region, may operate in both the saturation region and the subthreshold region, may operate in both the subthreshold region and the linear region, or may operate in the linear region, the saturation region, and the subthreshold region.
Next, the configuration of the circuit MP in
The circuit HC-2b has a configuration similar to that of the circuit HC. Thus, in the description of the circuit elements and the like included in the circuit HC-2b, the description is made using the reference numerals of the circuit elements included in the circuit HC in some cases.
In the circuit MC of the circuit MP in
Note that the circuit MCr of the circuit MP in
In the circuit MP in
In addition, in the circuit MP in
When the ratio of the W length to the L length of the transistor M1 is W/L, the ratio of the W length to the L length of the transistor M1-2b is preferably 2 W/L. In addition, the size of the transistor M1r is preferably equal to that of the transistor M1, and the size of the transistor M1-2br is preferably equal to that of the transistor M1-2b.
The wiring X1L2b is a wiring for switching the on state and the off state of the transistor M3-2b and the transistor M3-2br, and the wiring X2L2b is a wiring for switching the on state and the off state of the transistor M4-2b and the transistor M4-2br.
Next, a method for setting a current (a method for setting the first data (a weight coefficient)) in the circuit MP in
First, a high-level potential is supplied to the wiring WX1L and the wiring WL so that the transistor M3, the transistor M10, the transistor M9 of the circuit HC, and the transistor M9 of the circuit HC-2b are turned on. Accordingly, the potential of the node n3 of the circuit HC becomes VDD and the potential of the node n3 of the circuit HC-2b becomes VDD. After that, a current having the current amount of 3Iut is generated in the current source circuit ISC in
After that, a predetermined potential is supplied to each of the wiring WX1L, the wiring X2L, the wiring X1L2b, and the wiring X2L2b in accordance with the second data (a value of a signal of a neuron), whereby the circuit MP can calculate the product of the set first data (a weight coefficient) and the second data (a value of a signal of a neuron). Note that the calculation of the product of the multilevel first data (a weight coefficient) and the multilevel second data (a value of a signal of a neuron) are described in detail in Configuration example 5.
Note that the configuration of the circuit MP in
In the circuit MP in
The circuit MP in
Note that this configuration example can be combined with any of the other configuration examples and the like described in this specification as appropriate.
As shown in
As shown in
In the circuit BS in
When a “positive bias” is set in the circuit BS, a high-level potential is supplied to the wiring WXBS and the wiring WLBS so that the transistor M12, the transistor M13, a transistor M12r, and a transistor M13r are turned on, as in the operation of the circuit MP in
When a “negative bias” is set in the circuit BS, a high-level potential is supplied to the wiring WXBS and the wiring WLBS so that the transistor M12, the transistor M13, the transistor M12r, and the transistor M13r are turned on. After that, a current corresponding to the bias is selected in the current source circuit ISC in
When a “bias of 0” is set in the circuit BS, a high-level potential is supplied to the wiring WXBS and the wiring WLBS so that the transistor M12, the transistor M13, the transistor M12r, and the transistor M13r are turned on, electrical continuity is established between the wiring VCN and each of the wiring OL and the wiring OLB, and the potentials of the nodes n4 and n4r become VSS. After that, a low-level potential is supplied to the wiring WXBS and the wiring WLBS so that the transistor M12, the transistor M13, the transistor M12r, and the transistor M13r are turned off, and the potentials VSS of the node n4 and the node n4r are held, whereby the “bias of 0” can be set in the circuit BS.
Depending on the case, a potential other than VSS may be supplied to each of the node n4 and the node n4r when a bias is set in the circuit BS.
After a bias is set in the circuit BS, the first data (e.g., a weight coefficient here) is held in the circuit MP and the second data (e.g., a value of a signal of a neuron) is supplied to the circuit MP. Specifically, a current corresponding to the weight coefficient is set in the circuit MP, and a potential corresponding to the second data (a value of a signal of a neuron) is supplied from each of the wiring WX1L and the wiring X2L to the circuit MP. Furthermore, the wiring WXBS is set to have a high-level potential in the circuit BS, so that the bias set in the circuit BS can be applied to the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron), which is calculated in the circuit MP.
Alternatively, it is also possible to hold the first data (a weight coefficient) in the circuit MP in advance, calculate the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) in the circuit MP once, and then set a bias in the circuit BS on the basis of the calculation result and perform arithmetic operation again. That is, operation for changing a bias may be performed as appropriate on the basis of the arithmetic operation result.
Although the wiring VF, the wiring VFr, the wiring VE, and the wiring VEr are illustrated in the configuration example in
Note that this configuration example can be combined with any of the other configuration examples and the like described in this specification as appropriate.
Next, an example of a circuit configuration that can be applied to the circuit MP illustrated in
The circuit MP illustrated in
The circuit MCr of the circuit MP in
Note that in this specification and the like, unless otherwise specified, the transistor MZ in an on state may operate in a linear region in the end. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in the linear region. However, one embodiment of the present invention is not limited thereto. For example, the transistor MZ in an on state may operate in a saturation region or may operate in a subthreshold region. Alternatively, it may operate around the boundary between the saturation region and the subthreshold region. Alternatively, the transistor MZ may operate in both the linear region and the saturation region, may operate in both the saturation region and the subthreshold region, may operate in both the subthreshold region and the linear region, or may operate in the linear region, the saturation region, and the subthreshold region.
The circuit MC includes the circuit HC and a transistor M20, and the circuit MCr includes the circuit HCr and a transistor M20r.
A first terminal of the transistor M20 is electrically connected to the first terminal of the transistor MZ, a gate of the transistor M20 is electrically connected to the second terminal of the transistor M2 and the first terminal of the capacitor C1, and a second terminal of the transistor M20 is electrically connected to the wiring OL. The second terminal of the capacitor C1 is electrically connected to the wiring VL. The first terminal of the transistor M2 is electrically connected to the wiring OL.
A first terminal of the transistor M20r is electrically connected to the first terminal of the transistor MZ, a gate of the transistor M20r is electrically connected to the second terminal of the transistor M2r and the first terminal of the capacitor C1r, and a second terminal of the transistor M20r is electrically connected to the wiring OLB. A second terminal of the capacitor C1r is electrically connected to the wiring VL. The first terminal of the transistor M2r is electrically connected to the wiring OLB.
The wiring VL functions as a wiring for supplying a constant voltage, for example. The constant voltage can be a low-level potential VSS or a ground potential (GND), for example.
As in the circuit HC and the circuit HCr included in the circuit MP illustrated in
Here, for example, the weight coefficient set in the circuit MP in
When a current corresponding to a weight coefficient is set in each of the circuit HC and the circuit HCr, the gate potentials of the transistor M20 and the transistor M20r are determined. Here, when a potential corresponding to the value of a signal of a neuron is supplied to the wiring XL, for example, a current flowing between the circuit MP and the wiring OL and/or the wiring OLB is determined. For example, when a high-level potential is supplied as the second data of “+1” to the wiring XL, the constant voltage supplied from the wiring VL is supplied to the first terminal of the transistor M20 and the first terminal of the transistor M20r. Alternatively, for example, when a low-level potential is supplied as the second data of “0” to the wiring XL, the constant voltage supplied from the wiring VL is not supplied to the first terminal of the transistor M20 and the first terminal of the transistor M20r. That is, a current does not flow through the transistor M20 and the transistor M20r.
When a current with the amount Iut is set in the transistor M20 and a potential is supplied from the wiring VL to the source of the transistor M20, the current with the amount Iut flows between the first terminal and the second terminal of the transistor M20. When a current is set not to flow through the transistor M20, a current does not flow between the first terminal and the second terminal of the transistor M20 even when a potential is supplied from the wiring VL to the source of the transistor M20. Similarly, when the current with the amount Iut is set in the transistor M20r and a potential is supplied from the wiring VL to the source of the transistor M20r, the current with the amount Iut flows between the first terminal and the second terminal of the transistor M20r. When a current is set not to flow through the transistor M20r, a current does not flow between the first terminal and the second terminal of the transistor M20r even when a potential is supplied from the wiring VL to the source of the transistor M20r.
That is, the summary of the above description is as follows: when the product of a weight coefficient and a value of a signal of a neuron is “+1”, the current with the amount Iut flows between the circuit MC and the wiring OL and a current does not flow between the circuit MCr and the wiring OLB. When the product of a weight coefficient and a value of a signal of a neuron is “−1”, the current with the amount Iut flows between the circuit MCr and the wiring OLB and a current does not flow between the circuit MC and the wiring OL. When the product of a weight coefficient and a value of a signal of a neuron is “0”, a current does not flow between the circuit MC and the wiring OL and a current does not flow between the circuit MCr and the wiring OLB.
As described above, the circuit MP in
The circuit MP illustrated in
The wiring CVL functions as a wiring for supplying a constant voltage, for example. The constant voltage can be, for example, a high-level potential, a low-level potential, a ground potential, or the like.
Note that this configuration example can be combined with any of the other configuration examples and the like described in this specification as appropriate.
Note that this embodiment can be combined with any of the other embodiments in this specification as appropriate.
This embodiment describes semiconductor devices capable of product-sum operation of the multilevel first data (e.g., one of a weight coefficient and a signal of a neuron) and the multilevel second data (e.g., the other of the weight coefficient and the signal of a neuron (an arithmetic value)) and operation methods of the semiconductor devices.
First, described here is an operation method example of the product-sum operation of the multilevel first data (e.g., one of a weight coefficient and a signal of a neuron) and the multilevel second data (e.g., the other of the weight coefficient and the signal of a neuron (an arithmetic value)) performed using the semiconductor device described in the above embodiments, for example.
As an example, an operation method of the arithmetic circuit 150 in
In the timing chart shown in
In the operation example of the timing chart in
After Time T11, the switch SWO and the switch SWOB are turned on and the switch SWI, the switch SWIB, the switch SWL, the switch SWLB, the switch SWH, and the switch SWHB are turned off in
From Time T12 to Time T13, the second data (e.g., a value of a signal of a neuron here) is input to the circuit MP. Note that the input time from Time T12 to Time T13 is denoted by tut. The length of the input time corresponds to the level of the value of a signal of a neuron. That is, by changing the length of the input time, the arithmetic operation result can be changed.
In the operation example in
At this time, the transistor M1 is set such that a current having the current amount of I1 flows, and thus the current having the current amount of I1 flows from the circuit ACTF to the wiring VE through the switching circuit TW, the wiring OL, and the circuit MC. Since the transistor M1r is in an off state (is set such that the current amount of 0 is supplied), a current does not flow from the circuit ACTF to the wiring VEr through the switching circuit TW, the wiring OLB, and the circuit MCr.
Here, attention is focused on the integrator circuit of the circuit ACTF. Since the second data (a value of a signal of a neuron) is input from Time T12 to Time T13, charge is continuously accumulated from Time T12 to Time T13 in the capacitor (the load LEa) of the integrator circuit included in the circuit ACTF, which has electrical continuity with the wiring OL. Ideally, charge of tut×I1 is accumulated in the capacitor at Time T13. Note that in the timing chart in
Next, the case is considered where the input time of a signal of a neuron to the circuit MP in the timing chart in
Operations before Time T12 in the timing chart in
From Time T12 to Time T14 in the operation example in
In the operation example in
Since the second data (a value of a signal of a neuron) is input from Time T12 to Time T14, charge is continuously accumulated from Time T12 to Time T14 in the capacitor (the load LEa) of the integrator circuit, which has electrical continuity with the wiring OL. Ideally, charge of 2tut×I1 (=2Q1) is accumulated in the capacitor at Time T14. Note that in the timing chart in
Next, the case is considered where the weight coefficient set in the circuit MP is changed from “+1” to “−2” in the timing chart in
Operations before Time T12 in the timing chart in
From Time T12 to Time T13 in the operation example in
In the operation example in
Since the second data (a value of a signal of a neuron) is input from Time T12 to Time T13, charge is continuously accumulated from Time T12 to Time T13 in the capacitor (the load LEb) of the integrator circuit, which has electrical continuity with the wiring OLB. Ideally, charge of tut×I2 (=2tut×I1=2Q1) is accumulated in the capacitor at Time T13. Note that in the timing chart in
As described in the operation examples in
In this operation example, the second data (a value of a signal of a neuron) input to the circuit MP can be defined as follows, for example. The second data (a value of a signal of a neuron) at the time when a high-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L for an input period of tut is “+1”; the second data (a value of a signal of a neuron) at the time when a high-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L for an input period of 2tut is “+2”; and the second data (a value of a signal of a neuron) at the time when a high-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L for an input period of 3tut is “+3”. In addition, the second data (a value of a signal of a neuron) at the time when a low-level potential is input to the wiring WX1L and a high-level potential is input to the wiring X2L for an input period of tut is “−1”; the second data (a value of a signal of a neuron) at the time when a low-level potential is input to the wiring WX1L and a high-level potential is input to the wiring X2L for an input period of 2tut is “−2”; and the second data (a value of a signal of a neuron) at the time when a low-level potential is input to the wiring WX1L and a high-level potential is input to the wiring X2L for an input period of 3tut is “−3”. Furthermore, the second data (a value of a signal of a neuron) at the time when a low-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L is “0”.
By defining the second data (a value of a signal of a neuron) input to the circuit MP as described above, “+1” can be obtained as the product of the first data (a weight coefficient) of “+1” and the second data (a value of a signal of a neuron) of “+1” in the operation example shown in
One embodiment of the present invention is not limited to the above definition. Although the second data (a value of a signal of a neuron) is defined above as a positive multilevel value, a negative multilevel value, or 0, the second data (a value of a signal of a neuron) can be processed as an analog value by using not a discrete value but a continuous value as the input period (by setting the input period to a×tut, where a is a positive real number).
Although the first data (a weight coefficient) set in the circuit MP is “+1” in the operation examples shown in
In the operation examples shown in
Although the arithmetic circuit 150 in
Note that this operation method example can be combined with any of the other operation method examples and the like described in this specification as appropriate.
Next, other operation method examples different from the operation examples shown in
As an example, an operation method of the arithmetic circuit 150 in
In the timing chart shown in
In the operation example of the timing chart in
After Time T21, the switch SWO and the switch SWOB are turned on and the switch SWI, the switch SWIB, the switch SWL, the switch SWLB, the switch SWH, and the switch SWHB are turned off in
After Time T22, the second data (e.g., a value of a signal of a neuron here) is input to the circuit MP. Note that in the operation example in
In the operation example in
At this time, the transistor M1 is set such that the current amount of I1 is supplied, and thus a current having the current amount of I1 flows from the circuit ACTF to the wiring VE through the switching circuit TW, the wiring OL, and the circuit MC in the first subperiod and the third subperiod. In the second subperiod, a low-level potential is input to the wiring WX1L and the wiring X2L and the low-level potential is input to the gates of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r; thus, the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r are turned off, and a current does not flow from the circuit ACTF to the wiring VE through the switching circuit TW, the wiring OL, and the circuit MC.
Since the transistor M1r is in an off state (is set such that the current amount of 0 is supplied) in the first subperiod, the second subperiod, and the third subperiod, a current does not flow from the circuit ACTF to the wiring VEr through the switching circuit TW, the wiring OLB, and the circuit MCr.
Here, attention is focused on the integrator circuit of the circuit ACTF. Since the second data (a signal of a neuron) is input after Time T22, charge is continuously accumulated after Time T22 in the capacitor (the load LEa) of the integrator circuit included in the circuit ACTF, which has electrical continuity with the wiring OL. Ideally, charge of tut×I1 is accumulated in the capacitor in the first subperiod and charge of 4tut×I1 is accumulated in the third subperiod. Note that in the timing chart in
Next, the case is considered where the input period of a signal of a neuron to the circuit MP in the timing chart in
Operations before Time T22 in the timing chart in
In the operation example in
In the operation example in
Since the transistor M1r is in an off state (is set such that the current amount of 0 is supplied) in the first subperiod, the second subperiod, and the third subperiod, a current does not flow from the circuit ACTF to the wiring VEr through the switching circuit TW, the wiring OLB, and the circuit MCr.
Since the second data (a value of a signal of a neuron) is input after Time T22, charge is continuously accumulated after Time T22 in the capacitor (the load LEa) of the integrator circuit, which has electrical continuity with the wiring OL. Ideally, charge of 2tut×I1 is accumulated in the capacitor at Time T25. Note that in the timing chart in
Next, the case is considered where the weight coefficient set in the circuit MP in the timing chart in
In the timing chart shown in
Operations before Time T22 in the timing chart in
In the operation example in
In the operation example in
Since the transistor M1 is in an off state (is set such that the current amount of 0 is supplied) in the first subperiod, the second subperiod, and the third subperiod, a current does not flow from the circuit ACTF to the wiring VE through the switching circuit TW, the wiring OL, and the circuit MC.
Since the second data (a signal of a neuron) is input after Time T22, charge is continuously accumulated after Time T22 in the capacitor (the load LEb) of the integrator circuit, which has electrical continuity with the wiring OLB. Ideally, charge of 6tut×I1 (=tut×2I1+2tut×2I1) is accumulated in the capacitor at Time T25. Note that in the timing chart in
As described in the operation examples shown in
In this operation example, the second data (a value of a signal of a neuron) input to the circuit MP can be defined as follows, for example. The second data (a value of a signal of a neuron) at the time when a high-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L only in the first subperiod is “+1”; the second data (a value of a signal of a neuron) at the time when a high-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L only in the second subperiod is “+2”; and the second data (a value of a signal of a neuron) at the time when a high-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L only in the third subperiod is “+4”. The second data (a value of a signal of a neuron) at the time when a low-level potential is input to the wiring WX1L and a high-level potential is input to the wiring X2L only in the first subperiod is “−1”; the second data (a value of a signal of a neuron) at the time when a low-level potential is input to the wiring WX1L and a high-level potential is input to the wiring X2L only in the second subperiod is “−2”; and the second data (a value of a signal of a neuron) at the time when a low-level potential is input to the wiring WX1L and a high-level potential is input to the wiring X2L only in the third subperiod is “−4”. Furthermore, the second data (a value of a signal of a neuron) at the time when a low-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L in the first subperiod, the second subperiod, and the third subperiod is “0”.
In the case where the second data (a value of a signal of a neuron) is to be “+3”, a high-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L only in the first subperiod and the second subperiod, and in the case where the second data (a value of a signal of a neuron) is to be “+5”, a high-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L in the first subperiod and the third subperiod. In the case where the second data (a value of a signal of a neuron) is to be “−6”, a low-level potential is input to the wiring WX1L and a high-level potential is input to the wiring X2L only in the second subperiod and the third subperiod, and in the case where the second data (a value of a signal of a neuron) is to be “−7”, a low-level potential is input to the wiring WX1L and a high-level potential is input to the wiring X2L in the first subperiod, the second subperiod, and the third subperiod.
By defining the second data (a value of a signal of a neuron) input to the circuit MP as described above, “+5” can be obtained as the product of the first data (a weight coefficient) of “+1” and the second data (a value of a signal of a neuron) of “+5” in the operation example shown in
One embodiment of the present invention is not limited to the above definition. Although the first subperiod, the second subperiod, and the third subperiod are provided as periods during which the second data (a value of a signal of a neuron) can be input in the above description, four or more subperiods may be provided. For example, a period during which the second data (a value of a signal of a neuron) can be input is divided into the first subperiod to a T-th subperiod (T is an integer greater than or equal to 4), and the length of an s-th subperiod (s is an integer greater than or equal to 4 and less than or equal to T) is set to 2(s-1)×tut. Alternatively, for example, a period during which the second data (a value of a signal of a neuron) can be input may be divided into the first subperiod to the T-th subperiod (Tis an integer greater than or equal to 4), and the length of the s-th subperiod (s is an integer greater than or equal to 4 and less than or equal to T) may be set to s×tut. Alternatively, the second data (a value of a signal of a neuron) may be defined as a real number; for example, the second data (a value of a signal of a neuron) at the time when a high-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L only in the first subperiod may be “+0.1”, the second data (a value of a signal of a neuron) at the time when a high-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L only in the second subperiod may be “+0.2”, and the second data (a value of a signal of a neuron) at the time when a high-level potential is input to the wiring WX1L and a low-level potential is input to the wiring X2L only in the third subperiod may be “+0.4”.
Although the first data (a weight coefficient) set in the circuit MP is “+1” in the operation examples shown in
In the operation examples shown in
In the configuration where a plurality of subperiods are provided as periods during which the second data (a value of a signal of a neuron) can be input, one or more subperiods are selected from the plurality of subperiods, and signals are input in the selected period(s) as in the operation examples in
Although the arithmetic circuit 150 in
Note that this operation method example can be combined with any of the other operation method examples and the like described in this specification as appropriate.
Described here is an operation method example of the arithmetic circuit 150 in
As in Operation method example 1 and Operation method example 2, to avoid complexity of description, a current flowing through the wiring OL and the wiring OLB is changed by only one circuit MP electrically connected to the wiring OL and the wiring OLB. The wiring VE and the wiring VEr electrically connected to the circuit MP each supply VSS as a constant voltage to the circuit MP. The circuits ACTF[1] to ACTF[n] included in the circuit AFP are each the circuit ACTF having a configuration of an integrator circuit (or a current-charge (IQ) converter circuit), for example. For example, the circuit ACTF may have a configuration in which the load LEa and the load LEb in the circuit ACTF[j] in
Specifically, in inputting the second data (e.g., a value of a signal of a neuron here) to the circuit MP, when the input time of a high-level potential to one of the wiring WX1L and the wiring X2L is tut, the input time of a high-level potential to one of the wiring X1L2b and the wiring X2L2b is 2tut and the input time of a high-level potential to one of the wiring X1L3b and the wiring X2L3b is 4tut in the operation. That is, the operation is performed such that when the time during which the transistor M3 and the transistor M3r are in an on state or the transistor M4 and the transistor M4r are in an on state is tut, the time during which the transistor M3-2b and the transistor M3-2br are in an on state or the transistor M4-2b and the transistor M4-2br are in an on state is 2tut and the time during which the transistor M3-3b and the transistor M3-3br are in an on state or the transistor M4-3b and the transistor M4-3br are in an on state is 4tut. Note that to show the difference in operation between the circuit MP in
As described in Operation method example 1 and Operation method example 2, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1 is determined by setting the first data (e.g., a weight coefficient here) in the circuit MP and setting the time during which the transistor M3 or the transistor M4 is in an on state. In addition, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1r is determined by setting the first data (a weight coefficient) in the circuit MP and setting the time during which the transistor M3r or the transistor M4r is in an on state.
Similarly, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1-2b and the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1-2br are also determined by setting the times during which the transistor M3-2b, the transistor M3-2br, the transistor M4-2b, and the transistor M4-2br are in an on state. In addition, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1-3b and the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1-3br are also determined by setting the times during which the transistor M3-3b, the transistor M3-3br, the transistor M4-3b, and the transistor M4-3br are in an on state.
Thus, the second data (a value of a signal of a neuron) set in the circuit MP can be defined as in the following table.
Here, the first data (a weight coefficient) of “+1” is set in the circuit MIP in advance, for example. Specifically, the transistor M1 is set such that the current amount of I1 is supplied, and the transistor M1r, the transistor M1-2br, and the transistor M1-3br are in an off state.
In the circuit MC, the sizes of the transistor M1, the transistor M1-2b, and the transistor M1-3b are equal to each other, the gates of the transistor M1, the transistor M1-2b, and the transistor M1-3b are electrically connected to the node n1 of the circuit UC, and the first terminals of the transistor M1, the transistor M1-2b, and the transistor M1-3b are electrically connected to the wiring VE; thus, almost equal currents flow between the sources and the drains of the transistor M1, the transistor M1-2b, and the transistor M1-3b. The amount of the current is denoted by Iut.
In the case where “±7” is input to the circuit MP as the second data (a value of a signal of a neuron), the transistor M3 is in an on state only for the time tut and the transistor M4 is in an off state, so that the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1 is tut×Iut. Note that tut×Iut=Qut is satisfied here. Similarly, the transistor M3-2b is in an on state only for the time 2tut and the transistor M4-2b is in an off state, so that the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1-2b is 2tut×Iut=2Qut. The transistor M3-3b is in an on state only for the time 4tut and the transistor M4-3b is in an off state, so that the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1-3b is 4tut×Iut=4Qut. Thus, the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC is Qut+2Qut+4Qut=7Qut. Meanwhile, the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is 0 because the transistor M1r, the transistor M1-2br, and the transistor M1-3br are in an off state.
In the case where “−7” is input to the circuit MP as the second data (a value of a signal of a neuron), electrical continuity is established between the wiring OLB and the circuit MC and between the wiring OL and the circuit MCr, and electrical continuity is not established between the wiring OLB and the circuit MCr and between the wiring OL and the circuit MC; hence, the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC is Qut+2Qut+4Qut=7Qut and the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr is 0.
As another example, the first data (a weight coefficient) of “−1” is set in the circuit MP in advance. Specifically, the transistor M1r is set such that the current amount of I1 is supplied and the transistor M1, the transistor M1-2b, and the transistor M1-3b are in an off state.
In the circuit MCr, the sizes of the transistor M1r, the transistor M1-2br, and the transistor M1-3br are equal to each other, the gates of the transistor M1r, the transistor M1-2br, and the transistor M1-3br are electrically connected to the node n1r of the circuit HCr, and the first terminals of the transistor M1r, the transistor M1-2br, and the transistor M1-3br are electrically connected to the wiring VEr. Thus, almost equal currents flow between the sources and the drains of the transistor M1r, the transistor M1-2br, and the transistor M1-3br. Like the current flowing between the source and the drain of the transistor M1, the amount of the current is denoted by Iut.
In the case where “+7” is input to the circuit MP as the second data (a value of a signal of a neuron), the transistor M3r is in an on state only for the time tut and the transistor M4r is in an off state, so that the amount of charge flowing from the wiring OLB to the wiring VEr through the transistor M1r is tut×Iut=Qut. Similarly, the transistor M3-2br is in an on state only for the time 2tut and the transistor M4-2br is in an off state, so that the amount of charge flowing from the wiring OLB to the wiring VEr through the transistor M1-2br is 2tut×Iut=2Qut. The transistor M3-3br is in an on state only for the time 4tut and the transistor M4-3br is in an off state, so that the amount of charge flowing from the wiring OLB to the wiring VEr through the transistor M1-3br is 4tut×Iut=4Qut. Thus, the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is Qut+2Qut+4Qut=7Qut. Meanwhile, the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC is 0 because the transistor M1, the transistor M1-2b, and the transistor M1-3b are in an off state.
In the case where “−7” is input to the circuit MP as the second data (a value of a signal of a neuron), electrical continuity is established between the wiring OLB and the circuit MC and between the wiring OL and the circuit MCr, and electrical continuity is not established between the wiring OLB and the circuit MCr and between the wiring OL and the circuit MC; hence, the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr is Qut+2Qut+4Qut=7Qut and the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC is 0.
Thus, by setting the first data (a weight coefficient) of “+1” in the circuit MP and selecting one or more transistors to be turned on from the transistor M3, the transistor M3-2b, and the transistor M3-3b included in the circuit MP in accordance with the positive second data (a value of a signal of a neuron), the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC can be any one of Qut, 2Qut, 3Qut, 4Qut, 5Qut, 6Qut, and 7Qut. Note that the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is 0 at this time. By setting the first data (a weight coefficient) of “−1” in the circuit MP and selecting one or more transistors to be turned on from the transistor M3r, the transistor M3-2br, and the transistor M3-3br included in the circuit MP in accordance with the positive second data (a value of a signal of a neuron), the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr can be any one of Qut, 2Qut, 3Qut, 4Qut, 5Qut, 6Qut, and 7Qut. Note that the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC is 0 at this time.
By setting the first data (a weight coefficient) of “+1” in the circuit MP and selecting one or more transistors to be turned on from the transistor M4, the transistor M4-2b, and the transistor M4-3b included in the circuit MP in accordance with the negative second data (a value of a signal of a neuron), the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC can be any one of Qut, 2Qut, 3Qut, 4Qut, 5Qut, 6Qut, and 7Qut. Note that the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr is 0 at this time. By setting the first data (a weight coefficient) of “−1” in the circuit MP and selecting one or more transistors to be turned on from the transistor M4r, the transistor M4-2br, and the transistor M4-3br included in the circuit MP in accordance with the negative second data (a value of a signal of a neuron), the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr can be any one of Qut, 2Qut, 3Qut, 4Qut, 5Qut, 6Qut, and 7Qut. Note that the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC is 0 at this time.
Assume that the first data (a weight coefficient) set in the circuit MP is changed from “+1” to “A” that is a positive integer, for example. Specifically, the transistor M1 is set such that a current amount of IA (=ΔI1) is supplied and the transistor M1r, the transistor M1-2br, and the transistor M1-3br are in an off state. In this case, the amount of current flowing between the sources and the drains of the transistor M1-2b and the transistor M1-3b is also IA. Thus, by selecting one or more transistors to be turned on from the transistor M3, the transistor M3-2b, and the transistor M3-3b included in the circuit MP in accordance with the second data (a value of a signal of a neuron), the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC becomes any one of AQut, 2AQut, 3QAut, 4AQut, 5AQut, 6AQut, and 7AQut. When “A” is a negative integer, the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is any one of AQut, 2AQut, 3QAut, 4AQut, 5AQut, 6AQut, and 7AQut.
In the case where the first data (a weight coefficient) of “0” is set in the circuit MP in advance, the transistor M1 and the transistor M1r are in an off state. Thus, a current does not flow from the wiring OL or the wiring OLB to the wiring VE through the circuit MC, and a current does not flow from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr. In other words, the amount of charge flowing through the wiring OL and the wiring OLB is 0.
Here, attention is focused on the integrator circuit of the circuit ACTF. When a current flows from the wiring OL or the wiring OLB to the wiring VE through the circuit MC or when a current flows from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr, the switch SWO and the switch SWOB are turned on and the switch SWI, the switch SWIB, the switch SWL, the switch SWLB, the switch SWH, and the switch SWHB are turned off in
The following table shows the charge amount QOL supplied through the wiring OL and the charge amount QOLB supplied through the wiring OLB in the case of the above operation example where the first data (a weight coefficient) is “+1” or “−1” and the second data (a value of a signal of a neuron) is defined as described above.
By setting the first data (a weight coefficient) and the second data (a value of a signal of a neuron) as described above, the charge amount QOL flowing from the wiring OL to the circuit MC or the circuit MCr and the charge amount QOLB flowing from the wiring OLB to the circuit MC or the circuit MCr are determined in accordance with the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron). In the case where the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a positive value, a current flows from the wiring OL to the circuit MC or the circuit MCr, and in the case where the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a negative value, a current flows from the wiring OLB to the circuit MC or the circuit MCr. That is, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be calculated from the charge amount QOL and the charge amount QOLB. For example, in the case where the first data (a weight coefficient) is “−1” or “+1”, the second data (a value of a signal of a neuron) is any one of “−7” to “+7”, and the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a positive number, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be calculated from the charge amount QOL by replacing Qut with “+1” in the charge amount QOL with which a current flows from the wiring OL to the circuit MC or the circuit MCr in the above table. Alternatively, for example, in the case where the first data (a weight coefficient) is “−1” or “+1”, the second data (a value of a signal of a neuron) is any one of “−7” to “+7”, and the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a negative number, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be calculated from the charge amount QOLB by replacing Qut with “−1” in the charge amount QOLB with which a current flows from the wiring OLB to the circuit MC or the circuit MCr in the above table.
Although the first data (a weight coefficient) set in the circuit MP is “+1” or “−1” in the above operation example, the first data (a weight coefficient) of “0”, an analog value, or the like may be used for calculation, for example. Thus, the circuit MP can perform the product-sum operation of the first data (a weight coefficient) that is a binary value, a multilevel value, an analog value, or the like and the second multilevel data (a value of a signal of a neuron) and/or arithmetic operation of an activation function.
One embodiment of the present invention is not limited to the above definition. Although the second data (a value of a signal of a neuron) is defined above as a positive multilevel value, a negative multilevel value, or 0, the second data (a value of a signal of a neuron) can be processed as an analog value by using not a discrete value but a continuous value as the input period (by setting the input period to a×tut, where a is a positive real number).
When the time during which the transistor M3 and the transistor M3r are in an on state or the transistor M4 and the transistor M4r are in an on state is tut, the time during which the transistor M3-2b and the transistor M3-2br are in an on state or the transistor M4-2b and the transistor M4-2br are in an on state is 2tut, and the time during which the transistor M3-3b and the transistor M3-3br are in an on state or the transistor M4-3b and the transistor M4-3br are in an on state is 4tut, for example, the second data (a value of a signal of a neuron) at the time when a high-level potential is input to the wiring WX1L, a low-level potential is input to the wiring X2L, and a low-level potential is input to the wiring X1L2b, the wiring X2L2b, the wiring X1L3b, and the wiring X2L3b may be defined as not “+1” but a real number such as “+0.1”.
In the semiconductor device of one embodiment of the present invention, the configuration of the circuit MP is not limited to that in
The semiconductor device of one embodiment of the present invention and the operation method of the semiconductor device are not limited to the above. Although the sizes of the transistor M1, the transistor M1r, the transistor M1-2b, the transistor M1-2br, the transistor M1-3b, and the transistor M1-3br of the circuit MP in
Here, the time during which the transistor M3 and the transistor M3r are in an on state or the transistor M4 and the transistor M4r are in an on state is tut, the time during which the transistor M3-2b and the transistor M3-2br are in an on state or the transistor M4-2b and the transistor M4-2br are in an on state is 2tut, and the time during which the transistor M3-3b and the transistor M3-3br are in an on state or the transistor M4-3b and the transistor M4-3br are in an on state is 2tut. That is, in inputting the second data (a value of a signal of a neuron) to the circuit MP, the input time of a high-level potential to one of the wiring WX1L and the wiring X2L is tut, the input time of a high-level potential to one of the wiring X1L2b and the wiring X2L2b is 2tut, and the input time of a high-level potential to one of the wiring X1L3b and the wiring X2L3b is 2tut. The circuit MP in
When the transistor M1 is set such that a current having the current amount of ut flows between the source and the drain, one of the transistor M3-3b and the transistor M4-3b is in an on state only for the time 2tut and the other of the transistor M3-3b and the transistor M4-3b is in an off state, so that the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1-3b is 2tut×2Iut=4Qut. Note that the conditions of the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1 and the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1-2b are the same as those of the above-described operation example, and thus the description is omitted.
When the transistor M1r is set such that a current having the current amount of ut flows between the source and the drain, one of the transistor M3-3br and the transistor M4-3br is in an on state only for the time 2tut and the other of the transistor M3-3br and the transistor M4-3br is in an off state, so that the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1-3br is 2tut×2Iut=4Qut. Note that the conditions of the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1r and the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1-2br are the same as those of the above-described operation example, and thus the description is omitted.
As described above, the sizes of the transistor M1, the transistor M1r, the transistor M1-2b, the transistor M1-2br, the transistor M1-3b, and the transistor M1-3br and the input time of a high-level potential to each of the wiring WX1L, the wiring X2L, the wiring X1L2b, the wiring X2L2b, the wiring X1L3b, and the wiring X2L3b are appropriately changed, whereby the operation can be similar to that of the operation example of the circuit MP shown in
In the semiconductor device of one embodiment of the present invention, the configuration of the circuit MP is not limited to that in
The operation method of the semiconductor device of one embodiment of the present invention is not limited to the above operation method. For example, as described in Operation method example 2, the input period of signals that are input to the wiring WX1L, the wiring X2L, the wiring X1L2b, the wiring X2L2b, the wiring X1L3b, and the wiring X2L3b may be divided into a plurality of subperiods.
In this operation method example, the case is considered where only one circuit MP is electrically connected to the wiring OL and the wiring OLB to avoid complexity of description; however, a plurality of circuits MP may be electrically connected to the wiring OL and the wiring OLB as in the arithmetic circuit 150 in
Although the arithmetic circuit 150 in
Note that this operation method example can be combined with any of the other operation method examples and the like described in this specification as appropriate.
Described here is an operation method example of the arithmetic circuit 150 in
As in Operation method example 1 to Operation method example 3, to avoid complexity of description, a current flowing through the wiring OL and the wiring OLB is changed by only one circuit MP electrically connected to the wiring OL and the wiring OLB. The wiring VE and the wiring VEr electrically connected to the circuit MP each supply VSS as a constant voltage to the circuit MP. The circuit ACTF[1] to the circuit ACTF[n] included in the circuit AFP are each the circuit ACTF having a configuration of an integrator circuit (or a current-charge (IQ) converter circuit), for example. The circuit ACTF may have a configuration in which the load LEa and the load LEb in the circuit ACTF[j] in
Specifically, when a current flows from the circuit AFP to the circuit MP, the input time of a high-level potential to one of the wiring WX1L and the wiring X2L is tut and the input time of a high-level potential to one of the wiring WX1L2b and the wiring X2L2b is 2tut in the operation. That is, the operation is performed such that when the time during which the transistor M3 and the transistor M3r are in an on state or the transistor M4 and the transistor M4r are in an on state is tut, the time during which the transistor M3-2b and the transistor M3-2br are in an on state or the transistor M4-2b and the transistor M4-2br are in an on state is 2tut. Thus, to show the difference in operation between the circuit MP in
As described in Operation method example 1 and Operation method example 2, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1 is determined by setting the first data (e.g., a weight coefficient here) in the circuit MP and setting the time during which the transistor M3 or the transistor M4 is in an on state. In addition, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1r is determined by setting the first data (a weight coefficient) in the circuit MP and setting the time during which the transistor M3r or the transistor M4r is in an on state.
Similarly, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1-2b and the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1-2br are also determined by setting the times during which the transistor M3-2b, the transistor M3-2br, the transistor M4-2b, and the transistor M4-2br are in an on state.
Note that VSS or V1 is held as a digital value (a binary value) in each of the circuit HC and the circuit HC-2b in
In a manner similar to the above, VSS or V1 is held as a digital value (a binary value) in each of the circuit HCr and the circuit HC-2br.
Here, the first data (a weight coefficient) set in the circuit MP is defined.
In the case where “+1” is set in the circuit MP as the first data (a weight coefficient), for example, the transistor M1 is set such that the current amount of I1 is supplied, and VSS is held in the circuit HC-2b, the circuit HCr, and the circuit HC-2br. The first terminal of the transistor M1 is electrically connected to the wiring OL through the transistor M3 and electrically connected to the wiring OLB through the transistor M4; thus, in the case where a high-level potential is input to one of the wiring WX1L and the wiring X2L, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1 is tut×I1. Here, tut×I1=Qut is satisfied. Since the transistor M1r, the transistor M1-2b, and the transistor M1-2br are in an off state, the amount of current flowing between the sources and the drains of the transistor M1r, the transistor M1-2b, and the transistor M1-2br is 0.
In the case where “+2” is set in the circuit MP as the first data (a weight coefficient), the transistor M1-2b is set such that the current amount of I1 is supplied, and VSS is held in the circuit HC, the circuit HCr, and the circuit HC-2br. The first terminal of the transistor M1-2b is electrically connected to the wiring OL through the transistor M3-2b and electrically connected to the wiring OLB through the transistor M4-2b; thus, in the case where a high-level potential is input to one of the wiring WX1L2b and the wiring X2L2b, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1-2b is 2tut×I1=2Qut. Since the transistor M1, the transistor M1r, and the transistor M1-2br are in an off state, the amount of current flowing between the sources and the drains of the transistor M1, the transistor M1r, and the transistor M1-2br is 0.
In the case where “+3” is set in the circuit MP as the first data (a weight coefficient), the transistor M1 and the transistor M1-2b are set such that the current amount of I1 is supplied, and VSS is held in the circuit HCr and the circuit HC-2br. As described above, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1 is tut×I1 in the case where a high-level potential is input to one of the wiring WX1L and the wiring X2L, and the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1 is 2tut×I1 in the case where a high-level potential is input to one of the wiring WX1L2b and the wiring X2L2b. Thus, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the circuit MC is tut×I1+2tut×I1=3Qut. Since the transistor M1r and the transistor M1-2br are in an off state, the amount of current flowing between the sources and the drains of the transistor M1r and the transistor M1-2br is 0.
In the case where the first data (a weight coefficient) is “−1”, the transistor M1r is set such that the current amount of I1 is supplied, and VSS is held in the circuit HC, the circuit HC-2b, and the circuit HC-2br. The first terminal of the transistor M1r is electrically connected to the wiring OLB through the transistor M3r and electrically connected to the wiring OL through the transistor M4r; thus, in the case where a high-level potential is input to one of the wiring WX1L and the wiring X2L, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1r is tut×I1. Here, tut×I1=Qut is satisfied. Since the transistor M1r, the transistor M1-2b, and the transistor M1-2br are in an off state, the amount of current flowing between the sources and the drains of the transistor M1, the transistor M1-2b, and the transistor M1-2br is 0.
In the case where “−2” is set in the circuit MP as the first data (a weight coefficient), the transistor M1-2br is set such that the current amount of I1 is supplied, and VSS is held in the circuit HC, the circuit HCr, and the circuit HC-2b. The first terminal of the transistor M1-2br is electrically connected to the wiring OLB through the transistor M3-2br and electrically connected to the wiring OL through the transistor M4-2br; thus, in the case where a high-level potential is input to one of the wiring WX1L2b and the wiring X2L2b, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1-2br is 2tut×I1=2Qut. Since the transistor M1, the transistor M1r, and the transistor M1-2b are in an off state, the amount of current flowing between the sources and the drains of the transistor M1, the transistor M1r, and the transistor M1-2b is 0.
In the case where “−3” is set in the circuit MP as the first data (a weight coefficient), the transistor M1r and the transistor M1-2br are each set such that the current amount of I1 is supplied, and VSS is held in the circuit HC and the circuit HC-2b. As described above, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1r is tut×I1 in the case where a high-level potential is input to one of the wiring WX1L and the wiring X2L, and the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through a transistor M1r-2br is 2tut×I1 in the case where a high-level potential is input to one of the wiring WX1L2b and the wiring X2L2b. Thus, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr is tut×I1+2tut×I1=3Qut. Since the transistor M1 and the transistor M1-2b are in an off state, the amount of current flowing between the sources and the drains of the transistor M1 and the transistor M1-2b is 0.
In the case where the first data (a weight coefficient) is “0”, VSS is held in the circuit HC, the circuit HCr, the circuit HC-2b, and the circuit HC-2br. Thus, the amount of current flowing between the sources and the drains of the transistor M1, the transistor M1r, the transistor M1-2b, and the transistor M1-2br is 0.
That is, a digital value (a binary value) is held in the circuit HC, the circuit HCr, the circuit HC-2b, and the circuit HC-2br, the input period of a high-level potential to one of the wiring WX1L and the wiring X2L is set to tut, and the input period of a high-level potential to one of the wiring WX1L2b and the wiring X2L2b is set to 2tut, whereby the first data (a weight coefficient) having multiple levels (in this operation example, seven levels “−3”, “−2”, “−1”, “0”, “+1”, “+2”, and “+3”) can be expressed.
Note that in this operation example, the second data (e.g., a signal of a neuron here) input to the circuit MP is defined as follows, for example: a high-level potential is input to the wiring WX1L and the wiring X1L2b and a low-level potential is input to the wiring X2L and the wiring X2L2b when the second data is “+1”; a low-level potential is input to the wiring WX1L and the wiring X1L2b and a high-level potential is input to the wiring X2L and the wiring X2L2b when the second data is “−1”; and a low level potential is input to the wiring WX1L, the wiring X1L2b, the wiring X2L, and the wiring X2L2b when the second data is “0”.
Here, attention is focused on the integrator circuit of the circuit ACTF. When a current flows from the wiring OL or the wiring OLB to the wiring VE through the circuit MC or when a current flows from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr, the switch SWO and the switch SWOB are turned on and the switch SWI, the switch SWIB, the switch SWL, the switch SWLB, the switch SWH, and the switch SWHB are turned off in
The following table shows the charge amount QOL supplied through the wiring OL and the charge amount QOLB supplied through the wiring OLB in the case of the above operation example where the first data (a weight coefficient) is set to any one of “+3”, “+2”, “+1”, “0”, “−1”, “−2”, and “−3” and the second data (a value of a signal of a neuron) is defined as described above.
By setting the first data (a weight coefficient) and the second data (a value of a signal of a neuron) as described above, the charge amount QOL with which a current flows from the wiring OL to the circuit MC or the circuit MCr and the charge amount QOLB with which a current flows from the wiring OLB to the circuit MC or the circuit MCr are determined in accordance with the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron). In the case where the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a positive value, a current flows from the wiring OL to the circuit MC or the circuit MCr, and in the case where the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a negative value, a current flows from the wiring OLB to the circuit MC or the circuit MCr. That is, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be calculated from the charge amount QOL and the charge amount QOLB. For example, in the case where the first data (a weight coefficient) is “−3” to “+3”, the second data (a value of a signal of a neuron) is any one of “−1”, “0”, and “+1”, and the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a positive number, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be calculated from the charge amount QOL by replacing Qut with “+1” in the charge amount QOL with which a current flows from the wiring OL to the circuit MC or the circuit MCr in the above table. Alternatively, for example, in the case where the first data (a weight coefficient) is “−1” or “+1”, the second data (a value of a signal of a neuron) is any one of “−7” to “+7”, and the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a negative number, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be calculated from the charge amount QOLB by replacing Qut with “−1” in the charge amount QOLB with which a current flows from the wiring OLB to the circuit MC or the circuit MCr in the above table.
Although the first data (a weight coefficient) set in the circuit MP is “+3”, “+2”, “+1”, “0”, “−1”, “−2”, or “−3” in the above operation example, the first data (a weight coefficient) may be used as an analog value or the like by adjusting the input time of a high-level potential to the wiring WX1L, the wiring X2L, the wiring WX1L2b, and the wiring X2L2b. Thus, the circuit MP can perform the product-sum operation of the first data (a weight coefficient) that is an analog value or the like and the multilevel second data (a value of a signal of a neuron) and/or arithmetic operation of an activation function.
In the semiconductor device of one embodiment of the present invention, the configuration of the circuit MP is not limited to that in
The operation method of the semiconductor device of one embodiment of the present invention is not limited to the above. For example, as described in Operation method example 2, the input period of signals that are input to the wiring WX1L, the wiring X2L, the wiring WX1L2b, and the wiring X2L2b may be divided into a plurality of subperiods or may be shortened or lengthened. In the latter case, as a specific example, the input time of signals input to the wiring WX1L and the wiring X2L is Atut(A is a real number greater than 0) and the input time of signals input to the wiring WX1L2b and the wiring X2L2b is 2Atut in the above operation example, whereby product-sum operation of the first data and the second data can be performed with the second data (a value of a signal of a neuron) having an analog value or multiple levels other than three levels of “−1”, “0”, and “+1”.
In this operation method example, the case is considered where only one circuit MP is electrically connected to the wiring OL and the wiring OLB to avoid complexity of description; however, a plurality of circuits MP may be electrically connected to the wiring OL and the wiring OLB as in the arithmetic circuit 150 in
Although the arithmetic circuit 150 in
Note that this operation method example can be combined with any of the other operation method examples and the like described in this specification as appropriate.
Described here is an operation method example of the arithmetic circuit 150 in
As in Operation method example 1 to Operation method example 4, to avoid complexity of description, a current flowing through the wiring OL and the wiring OLB is changed by only one circuit MP electrically connected to the wiring OL and the wiring OLB. The wiring VE and the wiring VEr electrically connected to the circuit MP each supply VSS as a constant voltage to the circuit MP. The circuit ACTF[1] to the circuit ACTF[n] included in the circuit AFP are each the circuit ACTF having a configuration of an integrator circuit (or a current-charge (IQ) converter circuit), for example. The circuit ACTF may have a configuration in which the load LEa and the load LEb in the circuit ACTF[j] in
Specifically, in inputting the second data (e.g., a value of a signal of a neuron here) to the circuit MP, the input time of a high-level potential to one of the wiring X1L and the wiring X2L is set in accordance with the second data (a value of a signal of a neuron). That is, the time during which the transistor M3 and the transistor M3r are in an on state or the transistor M4 and the transistor M4r are in an on state is set.
As described in Operation method example 1, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1 is determined by setting the first data (e.g., a weight coefficient here) in the circuit MP and setting the time during which the transistor M3 or the transistor M4 is in an on state. In addition, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1r is determined by setting the first data (a weight coefficient) in the circuit MP and setting the time during which the transistor M3r or the transistor M4r is in an on state.
For example, given that the input time of a high-level potential to the wiring X1L is tut when the second data (a value of a signal of a neuron) is “+1”, and that a high-level potential is applied to the wiring X1L and a low-level potential is applied to the wiring X2L, the second data (a value of a signal of a neuron) of the other cases can be defined as in the following table. Note that the following table only shows integers from “−3” to “+3”.
As described in Configuration example 5 in Embodiment 2, the circuit HCS and the circuit HCSr can each have a configuration including an SRAM or a configuration including a NOSRAM. Here, a potential having a binary value (a digital value) is held in the circuit HCS and the circuit HCSr. Thus, for example, a high-level potential (e.g., VDDL here) is held in the circuit HCS and a low-level potential (e.g., VSS here) is held in the circuit HCSr when the first data (a weight coefficient) set in the circuit MP is “+1”; a low-level potential is held in the circuit HCS and a high-level potential is held in the circuit HCSr when the first data (a weight coefficient) set in the circuit MP is “−1”; and a low-level potential is held in the circuit HCS and a low-level potential is held in the circuit HCSr when the first data (a weight coefficient) set in the circuit MP is “0”.
Note that the amount of current flowing through the transistor M1 is I1 in the case where the voltage VDDL is held in the circuit HCS. The amount of current flowing through the transistor M1 is 0 in the case where the voltage VSS is held in the circuit HCS. Similarly, the amount of current flowing through the transistor M1r is I1 in the case where the voltage VDDL is held in the circuit HCSr, and the amount of current flowing through the transistor M1r is 0 in the case where the voltage VSS is held in the circuit HCSr.
Next, a specific operation example of the circuit MP in
The first data (a weight coefficient) of “+1” is set in the circuit MP in advance, for example.
In the case where “+3” is input to the circuit MP as the second data (a value of a signal of a neuron), the transistor M3 is in an on state only for the time 3tut and the transistor M4 is in an off state, so that the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1 is 3tut×Iut. Note that tut×Iut=Qut is satisfied here. Meanwhile, the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is 0 because the transistor M1r is in an off state.
In the case where “−3” is input to the circuit MP as the second data (a value of a signal of a neuron), electrical continuity is established between the wiring OLB and the circuit MC and between the wiring OL and the circuit MCr, and electrical continuity is not established between the wiring OLB and the circuit MCr and between the wiring OL and the circuit MC, so that the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC is 3tut×Iut=3Qut and the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr is 0.
In addition, the case is considered where the first data (a weight coefficient) of “−1” is set in the circuit MP in advance, for example.
In the case where “+3” is input to the circuit MP as the second data (a value of a signal of a neuron), the transistor M3r is in an on state only for the time 3tut and the transistor M4r is in an off state, so that the amount of charge flowing from the wiring OLB to the wiring VEr through the transistor M1r is 3tut×Iut=3Qut. Meanwhile, the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC is 0 because the transistor M1 is in an off state.
In the case where “−3” is input to the circuit MP as the second data (a value of a signal of a neuron), electrical continuity is established between the wiring OLB and the circuit MC and between the wiring OL and the circuit MCr, and electrical continuity is not established between the wiring OLB and the circuit MCr and between the wiring OL and the circuit MC, so that the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr is 3tut×Iut=3Qut and the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC is 0.
Here, attention is focused on the integrator circuit of the circuit ACTF. When a current flows from the wiring OL or the wiring OLB to the wiring VE through the circuit MC or when a current flows from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr, the switch SWO and the switch SWOB are turned on and the switch SWI, the switch SWIB, the switch SWL, the switch SWLB, the switch SWH, and the switch SWHB are turned off in
The following table shows the charge amount QOL supplied through the wiring OL and the charge amount QOLB supplied through the wiring OLB in the case of the above operation example where the first data (a weight coefficient) is “+1” or “−1” and the second data (a value of a signal of a neuron) is defined as described above.
When the second data (a value of a signal of a neuron) is an integer or a real number other than “−3”, “−2”, “−1”, “0”, “+1”, “+2”, and “+3”, the input time of a high-level potential to one of the wiring X1L and the wiring X2L is set in accordance with the integer or the real number. For example, by setting the input time to a×tut, where a is a positive real number, the second data (a value of a signal of a neuron) can be processed as an analog value.
Accordingly, the multilevel second data (a value of a signal of a neuron) can be supplied to the circuit MP, as in Operation method example 1 to Operation method example 3.
Note that as described above, the circuit HCS and the circuit HCSr included in the circuit MP in
In the case where one of a low-level potential and a high-level potential is held in the circuit HCS and the other of the low-level potential and the high-level potential is held in the circuit HCSr in the circuit MP in
The output terminal of the inverter circuit IV1 is electrically connected to the input terminal of the inverter circuit IV2, the first terminal of the transistor M3, and the first terminal of the transistor M4, and the output terminal of the inverter circuit IV2 is electrically connected to the input terminal of the inverter circuit IV1. The second terminal of the transistor M3 is electrically connected to the wiring OL, and the gate of the transistor M3 is electrically connected to the wiring WX1L. The second terminal of the transistor M4 is electrically connected to the wiring OLB, and the gate of the transistor M4 is electrically connected to the wiring X2L. An output terminal of the inverter circuit IV1r is electrically connected to an input terminal of the inverter circuit IV2r, the first terminal of the transistor M3r, and the first terminal of the transistor M4r, and an output terminal of the inverter circuit IV2r is electrically connected to an input terminal of the inverter circuit IV1r. The second terminal of the transistor M3r is electrically connected to the wiring OLB, and the gate of the transistor M3r is electrically connected to the wiring WX1L. The second terminal of the transistor M4r is electrically connected to the wiring OL, and the gate of the transistor M4r is electrically connected to the wiring X2L.
The circuit HCS has a function of holding one of a high-level potential and a low-level potential at the output terminal of the inverter circuit IV1 by the inverter loop circuit IVR, and the circuit HCSr has a function of holding one of a high-level potential and a low-level potential at the output terminal of the inverter circuit IV1r by the inverter loop circuit IVRr. Thus, as in
For the input of the second data (a value of a signal of a neuron) to the circuit MP in
The circuit MP in
The configuration of the circuit MP in
The circuit MP in
Note that the circuits MP in
As described above, the circuit HCS and the circuit HCSr included in the circuit MP in
In the circuit MP in
Alternatively, in the circuit MP in
To apply different voltages to the second terminal of the capacitor C2 and the first terminal of the transistor M1 in the circuit MP in
The operation method of the semiconductor device of one embodiment of the present invention is not limited to the above. For example, as described in Operation method example 2, the input period of signals that are input to the wiring X1L (the wiring WX1L in
In this operation method example, the case is considered where only one circuit MP is electrically connected to the wiring OL and the wiring OLB to avoid complexity of description; however, a plurality of circuits MP may be electrically connected to the wiring OL and the wiring OLB as in the arithmetic circuit 150 in
Although the arithmetic circuit 150 in
Note that this operation method example can be combined with any of the other operation method examples and the like described in this specification as appropriate.
Described here is an operation method example of the arithmetic circuit 120 in
As in Operation method example 1 to Operation method example 5, to avoid complexity of description, a current flowing through the wiring OL and the wiring OLB is changed by only one circuit MP electrically connected to the wiring OL and the wiring OLB. The wiring VE electrically connected to the circuit MP supplies VSS as a constant voltage to the circuit MP. The circuit ACTF[1] to the circuit ACTF[n] included in the circuit AFP are each the circuit ACTF having a configuration of an integrator circuit (or a current-charge (IQ) converter circuit), for example. The circuit ACTF may have a configuration in which the load LEa and the load LEb in the circuit ACTF[j] in
In
In the circuit MP in
For the structures of the transistor M3, the transistor M4, the transistor M3r, and the transistor M4r, the description of the transistor M3, the transistor M4, the transistor M3r, and the transistor M4r, which is mentioned elsewhere, is referred to.
The circuit HCS and the circuit HCSr can be, for example, an SRAM, a NOSRAM, or the like, like the circuit HCS and the circuit HCSr included in the circuit MP in
As a specific example,
The wiring X1L and the wiring X2L illustrated in
The wiring VE functions as a wiring that supplies a constant voltage. The constant voltage can be the ground potential or a low-level potential, for example.
Here, the operation characteristics of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r included in the circuit MP are described.
In
Here, Vg of the transistor is set so that the transistor is turned on when Vbg of the transistor is a high-level potential and that the transistor is turned off when Vbg of the transistor is a low-level potential. In
Alternatively, Vg of the transistor is set so that the transistor is turned off when Vbg of the transistor is a high-level potential and that the transistor is turned off when Vbg of the transistor is a low-level potential. In
For example, as shown in
In this specification and the like, a “low-level potential” and a “high-level potential” do not represent specified potentials, and specific potentials may vary depending on wirings. Thus, high-level potentials applied to the back gates of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r may be potentials different from high-level potentials (Vg1) applied to the wiring X1L and the wiring X2L. Similarly, low-level potentials applied to the back gates of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r may be potentials different from low-level potentials (Vg2) applied to the wiring X1L and the wiring X2L. For example, high-level potentials applied to the back gates of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r may be the same as the source potentials of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r. Alternatively, for example, low-level potentials applied to the back gates of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r may be potentials lower than the source potentials of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r. Thus, for example, in the case where the source potentials of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r are 0 V, low-level potentials applied to the back gates of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r are negative potentials and may be higher than or equal to −11 V and lower than or equal to −2 V, preferably around −3 V, for example.
Note that in the above-described operation example, potentials (Vg1 and Vg2) supplied to the wiring X1L and the wiring X2L and the back gate potentials of the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r are described as binary values (digital values), but one embodiment of the present invention is not limited thereto. For example, as shown in
As shown in
For example, as shown in
Alternatively, in inputting the second data (e.g., a value of a signal of a neuron here) to the circuit MP in
In
In
In this operation method example, the case is considered where only one circuit MP is electrically connected to the wiring OL and the wiring OLB to avoid complexity of description; however, a plurality of circuits MP may be electrically connected to the wiring OL and the wiring OLB as in the arithmetic circuit 120 in
Although the arithmetic circuit 120 in
Note that this operation method example can be combined with any of the other operation method examples and the like described in this specification as appropriate.
Described here is an operation method example of the arithmetic circuit 150 in
As in Operation method example 1 to Operation method example 6, to avoid complexity of description, a current flowing through the wiring OL and the wiring OLB is changed by only one circuit MP electrically connected to the wiring OL and the wiring OLB. The wiring VE and the wiring VEr electrically connected to the circuit MP each supply VSS as a constant voltage to the circuit MP. The circuits ACTF[1] to ACTF[n] included in the circuit AFP are each the circuit ACTF having a configuration of an integrator circuit (or a current-charge (IQ) converter circuit), for example. The circuit ACTF may have a configuration in which the load LEa and the load LEb in the circuit ACTF[j] in
Specifically, the input time of a high-level potential to one of the wiring X1L and the wiring X2L is set in accordance with the second data (e.g., a value of a signal of a neuron here) in the circuit MP, as in Operation method example 5. That is, the time during which the transistor M3 and the transistor M3r are in an on state or the transistor M4 and the transistor M4r are in an on state is set.
As described in Operation method example 1, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1 is determined by setting the first data (e.g., a weight coefficient here) in the circuit MP and setting the time during which the transistor M3 or the transistor M4 is in an on state. In addition, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1r is determined by setting the first data (a weight coefficient) in the circuit MP and setting the time during which the transistor M3r or the transistor M4r is in an on state.
The amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1-2b and the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1-2br are also determined by setting the times during which the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r are in an on state.
Thus, the second data (a value of a signal of a neuron) in the circuit MP in
As described in Configuration example 6 in Embodiment 2, the circuit HCS, the circuit HCS-2b, the circuit HCS-3b, the circuit HCSr, the circuit HCS-2br, and the circuit HCS-3br illustrated in
When the ratios of the W lengths to the L lengths of the transistor M1 and the transistor M1r are each W/L, the ratios of the W lengths to the L lengths of the transistor M1-2b and the transistor M1-2br are each 2 W/L, and the ratios of the W lengths to the L lengths of the transistor M1-3b and the transistor M1-3br are each 4 W/L.
Thus, for the first data (e.g., a weight coefficient here) set in the circuit MP, the contents of Configuration example 6 in Embodiment 2 can be referred to. Specifically, for example, the first data (a weight coefficient) set in the circuit MP is determined in accordance with currents flowing through the transistor M1, the transistor M1r, the transistor M1-2b, the transistor M1-2br, the transistor M1-3b, and the transistor M1-3br. In other words, the first data (a weight coefficient) set in the circuit MP is determined in accordance with potentials held in the circuit HCS, the circuit HCS-2b, the circuit HCS-3b, the circuit HCSr, the circuit HCS-2br, and the circuit HCS-3br. From the above, by holding potentials in the circuit HCS, the circuit HCS-2b, the circuit HCS-3b, the circuit HCSr, the circuit HCS-2br, and the circuit HCS-3br as in the following table, the first data (a weight coefficient) to be set in the circuit MP can be set.
Note that the amount of current flowing through the transistor M1 is I1 in the case where the voltage VDDL is held in the circuit HCS. Since the ratio of the W length to the L length of the transistor M1-2b is twice as high as the ratio of the W length to the L length of the transistor M1, the amount of current flowing through the transistor M1-2b is 2I1 in the case where the voltage VDDL is held in the circuit HCS-2b. Since the ratio of the W length to the L length of the transistor M1-3b is four times as high as the ratio of the W length to the L length of the transistor M1, the amount of current flowing through the transistor M1-3b is 4I1 in the case where the voltage VDDL is held in the circuit HCS-3b. Similarly, the amount of current flowing through the transistor M1r is I1 in the case where the voltage VDDL is held in the circuit HCSr, the amount of current flowing through the transistor M1-2br is 2I1 in the case where the voltage VDDL is held in the circuit HCS-2br, and the amount of current flowing through the transistor M1-3br is 4I1 in the case where the voltage VDDL is held in the circuit HCS-3br. Note that the amount of current flowing through the transistor M1, the transistor M1r, the transistor M1-2b, the transistor M1-2br, the transistor M1-3b, and the transistor M1-3br is 0 in the case where the voltage VSS is held in each of the circuit HCS, the circuit HCSr, the circuit HCS-2b, the circuit HCS-2br, the circuit HCS-3b, and the circuit HCS-2br.
Next, a specific operation example of the circuit MP in
The first data (a weight coefficient) of “+7” is set in the circuit MP in advance, for example. At this time, the current of ut flows between the source and the drain of the transistor M1, the current of 2Iut flows between the source and the drain of the transistor M1-2b, and the current of 4Iut flows between the source and the drain of the transistor M1-3b.
In the case where “+3” is input to the circuit MP as the second data (a value of a signal of a neuron), the transistor M3 is in an on state only for the time 3tut and the transistor M4 is in an off state, so that the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC is 3tut×Iut+3tut×2Iut+3tut×4Iut=21tut×Iut. Note that tut×Iut=Qut is satisfied here. That is, the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC is 21tut×Iut=21Qut. Meanwhile, the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is 0 because the transistor M1r, the transistor M1-2br, and the transistor M1-3br are in an off state.
In the case where “−3” is input to the circuit MP as the second data (a value of a signal of a neuron), electrical continuity is established between the wiring OLB and the circuit MC and between the wiring OL and the circuit MCr, and electrical continuity is not established between the wiring OLB and the circuit MCr and between the wiring OL and the circuit MC; hence, the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC is 21tut×Iut=21Qut and the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr is 0.
The case is considered where the first data (a weight coefficient) of “−7” is set in the circuit MP in advance, for example. At this time, the current of I1 flows between the source and the drain of the transistor M1r, the current of 2I1 flows between the source and the drain of the transistor M1-2br, and the current of 4I1 flows between the source and the drain of the transistor M1-3br.
In the case where “+3” is input to the circuit MP as the second data (a value of a signal of a neuron), the transistor M3r is in an on state only for the time 3tut and the transistor M4r is in an off state, so that the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is 3tut×Iut+3tut×2Iut+3tut×4Iut=21tut×Iut. That is, the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is 21tut×Iut=21Qut. Meanwhile, the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC is 0 because the transistor M1, the transistor M1-2b, and the transistor M1-3b are in an off state.
In the case where “−3” is input to the circuit MP as the second data (a value of a signal of a neuron), electrical continuity is established between the wiring OLB and the circuit MC and between the wiring OL and the circuit MCr, and electrical continuity is not established between the wiring OLB and the circuit MCr and between the wiring OL and the circuit MC; hence, the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr is 21tut×Iut=21Qut and the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC is 0.
The combination of potentials held in the circuit HCS, the circuit HCS-2b, the circuit HCS-3b, the circuit HCSr, the circuit HCS-2br, and the circuit HCS-3br is changed by changing the first data (a weight coefficient) set in the circuit MP, and accordingly the amount of current flowing through each of the transistor M1, the transistor M1r, the transistor M1-2b, the transistor M1-2br, the transistor M1-3b, and the transistor M1-3br changes. Thus, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the circuit MC and the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr can be determined in accordance with the first data (a weight coefficient).
In the case where the first data (a weight coefficient) of “0” is set in the circuit MP in advance, the transistor M1, the transistor M1r, the transistor M1-2b, the transistor M1-2br, the transistor M1-3b, and the transistor M1-3br are in an off state. Thus, a current does not flow from the wiring OL or the wiring OLB to the wiring VE through the circuit MC, and a current does not flow from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr. In other words, the amount of charge flowing through the wiring OL and the wiring OLB is 0.
In the case where “0” is input to the circuit MP as the second data (a value of a signal of a neuron), a low-level potential is input to the wiring X1L and the wiring X2L, and thus the transistor M3, the transistor M3r, the transistor M4, and the transistor M4r are turned off. Thus, a current does not flow from the wiring OL or the wiring OLB to the wiring VE through the circuit MC, and a current does not flow from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr. In other words, the amount of charge flowing through the wiring OL and the wiring OLB is 0.
When a current flows from the wiring OL or the wiring OLB to the wiring VE through the circuit MC or when a current flows from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr, the switch SWO and the switch SWOB are turned on and the switch SWI, the switch SWIB, the switch SWL, the switch SWLB, the switch SWH, and the switch SWHB are turned off in
By setting the first data (a weight coefficient) and the second data (a value of a signal of a neuron) as described above, the charge amount QOL with which a current flows from the wiring OL to the circuit MC or the circuit MCr and the charge amount QOLB with which a current flows from the wiring OLB to the circuit MC or the circuit MCr are determined in accordance with the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron). In the case where the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a positive value, a current flows from the wiring OL to the circuit MC or the circuit MCr, and in the case where the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a negative value, a current flows from the wiring OLB to the circuit MC or the circuit MCr. That is, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be calculated from the charge amount QOL and the charge amount QOLB. For example, in the case where the first data (a weight coefficient) is “+7” and the second data (a value of a signal of a neuron) is “+3”, QOL=21Qut and QOLB=0 are satisfied. In this case, a current flows from the wiring OL to the circuit MC or the circuit MCr, and thus the result of the product is a positive value. Accordingly, “+21” can be calculated from the charge amount QOL as the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron), for example, by replacing Qut with “+1” in the charge amount QOL with which a current flows from the wiring OL to the circuit MC or the circuit MCr. Alternatively, for example, when the first data (a weight coefficient) is “−7” and the second data (a value of a signal of a neuron) is “+3”, QOL=0 and QOLB=21Qut are satisfied. In this case, a current flows from the wiring OLB to the circuit MC or the circuit MCr, and thus the result of the product is a negative value. Accordingly, “−21” can be calculated from the charge amount QOLB as the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron), for example, by replacing Qut with “−1” in the charge amount QOLB with which a current flows from the wiring OLB to the circuit MC or the circuit MCr.
When the second data (a value of a signal of a neuron) is an integer or a real number other than “−3”, “−2”, “−1”, “0”, “+1”, “+2”, and “+3”, the input time of a high-level potential to one of the wiring X1L and the wiring X2L is set in accordance with the integer or the real number. For example, by setting the input time to a×tut, where a is a positive real number, the second data (a value of a signal of a neuron) can be processed as an analog value.
Accordingly, the multilevel second data (a value of a signal of a neuron) can be supplied to the circuit MP, as in Operation method example 1 to Operation method example 3 and Operation method example 5.
In the semiconductor device of one embodiment of the present invention, the configuration of the circuit MP is not limited to that in
The operation method of the semiconductor device of one embodiment of the present invention is not limited to the above. For example, as described in Operation method example 2, the input period of signals that are input to the wirings X1L and X2L may be divided into a plurality of subperiods in the circuit MP in
In this operation method example, the case is considered where only one circuit MP is electrically connected to the wiring OL and the wiring OLB to avoid complexity of description; however, a plurality of circuits MP may be electrically connected to the wiring OL and the wiring OLB as in the arithmetic circuit 150 in
Although the arithmetic circuit 150 in
Note that this operation method example can be combined with any of the other operation method examples and the like described in this specification as appropriate.
Described here is an operation method example of the arithmetic circuit 150 in
As in Operation method example 1 to Operation method example 7, to avoid complexity of description, a current flowing through the wiring OL and the wiring OLB is changed by only one circuit MP electrically connected to the wiring OL and the wiring OLB. The wiring VE and the wiring VEr electrically connected to the circuit MP each supply VSS as a constant voltage to the circuit MP. The circuits ACTF[1] to ACTF[n] included in the circuit AFP are each the circuit ACTF having a configuration of an integrator circuit (or a current-charge (IQ) converter circuit), for example. The circuit ACTF may have a configuration in which the load LEa and the load LEb in the circuit ACTF[j] in
Specifically, as in the circuit MP in
As described in Operation method example 1 and Operation method example 2, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1 is determined by setting the first data (e.g., a weight coefficient here) in the circuit MP and setting the time during which the transistor M3 or the transistor M4 is in an on state. In addition, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1r is determined by setting the first data (a weight coefficient) in the circuit MP and setting the time during which the transistor M3r or the transistor M4r is in an on state.
Similarly, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1-2b and the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1-2br are also determined by setting the times during which the transistor M3-2b, the transistor M3-2br, the transistor M4-2b, and the transistor M4-2br are in an on state. In addition, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1-3b and the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1-3br are also determined by setting the times during which the transistor M3-3b, the transistor M3-3br, the transistor M4-3b, and the transistor M4-3br are in an on state.
Thus, the second data (a value of a signal of a neuron) in the circuit MP in
As described in Configuration example 5 in Embodiment 2, the circuit HCS and the circuit HCSr illustrated in
Note that the amount of current flowing through the transistor M1 is I1 in the case where the voltage VDDL is held in the circuit HCS. The amount of current flowing through the transistor M1 is 0 in the case where the voltage VSS is held in the circuit HCS. Similarly, the amount of current flowing through the transistor M1r is Iut in the case where the voltage VDDL is held in the circuit HCSr, and the amount of current flowing through the transistor M1r is 0 in the case where the voltage VSS is held in the circuit HCSr.
In the circuit MC, the sizes of the transistor M1, the transistor M1-2b, and the transistor M1-3b are equal to each other, the gates of the transistor M1, the transistor M1-2b, and the transistor M1-3b are electrically connected to the circuit HCS, and the first terminals of the transistor M1, the transistor M1-2b, and the transistor M1-3b are electrically connected to the wiring VE; thus, almost equal currents flow between the sources and the drains of the transistor M1, the transistor M1-2b, and the transistor M1-3b. Therefore, the amount of current flowing between the sources and the drains of the transistor M1-2b and the transistor M1-3b is Iut as in the transistor M1. In addition, the sizes of the transistor M1r, the transistor M1-2br, and the transistor M1-3br are equal to that of the transistor M1, the gates of the transistor M1r, the transistor M1-2br, and the transistor M1-3br are electrically connected to the circuit HCSr, and the first terminals of the transistor M1r, the transistor M1-2br, and the transistor M1-3br are electrically connected to the wiring VEr; thus, a current flowing between the source and the drain of each of the transistor Mir, the transistor M1-2br, and the transistor M1-3br is equal to a current flowing between the source and the drain of the transistor M1. Therefore, the amount of current flowing between the source and the drain of each of the transistor Mir, the transistor M1-2br, and the transistor M1-3br is Iut as in the transistor M1.
Next, a specific operation example of the circuit MP in
The first data (a weight coefficient) of “+1” is set in the circuit MP in advance, for example.
In the case where “+7” is input to the circuit MP as the second data (a value of a signal of a neuron), the transistor M3 is in an on state only for the time tut and the transistor M4 is in an off state, so that the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1 is tut×Iut. Note that tut×Iut=Qut is satisfied here. Similarly, the transistor M3-2b is in an on state only for the time 2tut and the transistor M4-2b is in an off state, so that the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1-2b is 2tut×Iut=2Qut. The transistor M3-3b is in an on state only for the time 4tut and the transistor M4-3b is in an off state, so that the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1-3b is 4tut×Iut=4Qut. Thus, the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC is Qut+2Qut+4Qut=7Qut. Meanwhile, the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is 0 because the transistor M1r, the transistor M1-2br, and the transistor M1-3br are in an off state.
In the case where “−7” is input to the circuit MP as the second data (a value of a signal of a neuron), electrical continuity is established between the wiring OLB and the circuit MC and between the wiring OL and the circuit MCr, and electrical continuity is not established between the wiring OLB and the circuit MCr and between the wiring OL and the circuit MC; hence, the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC is Qut+2Qut+4Qut=7Qut and the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr is 0.
In addition, the case is considered where the first data (a weight coefficient) of “−1” is set in the circuit MP in advance, for example.
In the case where “+7” is input to the circuit MP as the second data (a value of a signal of a neuron), the transistor M3r is in an on state only for the time tut and the transistor M4r is in an off state, so that the amount of charge flowing from the wiring OLB to the wiring VEr through the transistor M1r is tut×Iut=Qut. Similarly, the transistor M4-2br is in an on state only for the time 2tut and the transistor M3-2br is in an off state, so that the amount of charge flowing from the wiring OLB to the wiring VEr through the transistor M1-2br is 2tut×Iut=2Qut. The transistor M4-3br is in an on state only for the time 4tut and the transistor M3-3br is in an off state, so that the amount of charge flowing from the wiring OLB to the wiring VEr through the transistor M1-3br is 4tut×Iut=4Qut. Thus, the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is Qut+2Qut+4Qut=7Qut. Meanwhile, the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC is 0 because the transistor M1, the transistor M1-2b, and the transistor M1-3b are in an off state.
In the case where “−7” is input to the circuit MP as the second data (a value of a signal of a neuron), electrical continuity is established between the wiring OLB and the circuit MC and between the wiring OL and the circuit MCr, and electrical continuity is not established between the wiring OLB and the circuit MCr and between the wiring OL and the circuit MC; hence, the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr is Qut+2Qut+4Qut=7Qut and the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC is 0.
Thus, by setting the first data (a weight coefficient) of “+1” in the circuit MP and selecting one or more transistors to be turned on from the transistor M3, the transistor M3-2b, and the transistor M3-3b included in the circuit MP in accordance with the positive second data (a value of a signal of a neuron), the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC can be any one of Qut, 2Qut, 3Qut, 4Qut, 5Qut, 6Qut, and 7Qut. Note that the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is 0 at this time. In addition, by setting the first data (a weight coefficient) of “−1” in the circuit MP and selecting one or more transistors to be turned on from the transistor M3r, the transistor M3-2br, and the transistor M3-3br included in the circuit MP in accordance with the positive second data (a value of a signal of a neuron), the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr can be any one of Qut, 2Qut, 3Qut, 4Qut, 5Qut, 6Qut, and 7Qut. Note that the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC is 0 at this time.
In addition, by setting the first data (a weight coefficient) of “+1” in the circuit MP and selecting one or more transistors to be turned on from the transistor M4, the transistor M4-2b, and the transistor M4-3b included in the circuit MP in accordance with the negative second data (a value of a signal of a neuron), the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC can be any one of Qut, 2Qut, 3Qut, 4Qut, 5Qut, 6Qut, and 7Qut. Note that the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr is 0 at this time. In addition, by setting the first data (a weight coefficient) of “−1” in the circuit MP and selecting one or more transistors to be turned on from the transistor M4r, the transistor M4-2br, and the transistor M4-3br included in the circuit MP in accordance with the negative second data (a value of a signal of a neuron), the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr can be any one of Qut, 2Qut, 3Qut, 4Qut, 5Qut, 6Qut, and 7Qut. Note that the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC is 0 at this time.
In the case where the first data (a weight coefficient) of “0” is set in the circuit MP in advance, the transistor M1, the transistor M1r, the transistor M1-2b, the transistor M1-2br, the transistor M1-3b, and the transistor M1-3br are in an off state. Thus, a current does not flow from the wiring OL or the wiring OLB to the wiring VE through the circuit MC, and a current does not flow from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr. In other words, the amount of charge flowing through the wiring OL and the wiring OLB is 0.
In the case where the second data (a value of a signal of a neuron) of “0” is input to the circuit MP, the transistor M3, the transistor M3-2b, the transistor M3-3b, the transistor M4, the transistor M4-2b, the transistor M4-3b, the transistor M3r, the transistor M3-2br, the transistor M3-3br, the transistor M4r, the transistor M4-2br, and the transistor M4-3br are in an off state. Thus, a current does not flow from the wiring OL or the wiring OLB to the wiring VE through the circuit MC, and a current does not flow from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr. In other words, the amount of charge flowing through the wiring OL and the wiring OLB is 0.
Here, attention is focused on the integrator circuit of the circuit ACTF. When a current flows from the wiring OL or the wiring OLB to the wiring VE through the circuit MC or when a current flows from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr, the switch SWO and the switch SWOB are turned on and the switch SWI, the switch SWIB, the switch SWL, the switch SWLB, the switch SWH, and the switch SWHB are turned off in
The following table shows the charge amount QOL supplied through the wiring OL and the charge amount QOLB supplied through the wiring OLB in the case of the above operation example where the first data (a weight coefficient) is “+1” or “−1” and the second data (a value of a signal of a neuron) is defined as described above.
By setting the first data (a weight coefficient) and the second data (a value of a signal of a neuron) as described above, the charge amount QOL with which a current flows from the wiring OL to the circuit MC or the circuit MCr and the charge amount QOLB with which a current flows from the wiring OLB to the circuit MC or the circuit MCr are determined in accordance with the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron). In the case where the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a positive value, a current flows from the wiring OL to the circuit MC or the circuit MCr, and in the case where the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a negative value, a current flows from the wiring OLB to the circuit MC or the circuit MCr. That is, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be calculated from the charge amount QOL and the charge amount QOLB. For example, in the case where the first data (a weight coefficient) is “−1” or “+1”, the second data (a value of a signal of a neuron) is any one of “−7” to “+7”, and the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a positive number, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be calculated from the charge amount QOL by replacing Qut with “+1” in the charge amount QOL with which a current flows from the wiring OL to the circuit MC or the circuit MCr in the above table. Alternatively, for example, in the case where the first data (a weight coefficient) is “−1” or “+1”, the second data (a value of a signal of a neuron) is any one of “−7” to “+7”, and the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a negative number, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be calculated from the charge amount QOLB by replacing Qut with “−1” in the charge amount QOLB with which a current flows from the wiring OLB to the circuit MC or the circuit MCr in the above table.
One embodiment of the present invention is not limited to the above definition. Although the second data (a value of a signal of a neuron) is defined above as a positive multilevel value, a negative multilevel value, or 0, the second data (a value of a signal of a neuron) can be processed as an analog value by using not a discrete value but a continuous value as the input period (by setting the input period to a×tut, where a is a positive real number).
When the time during which the transistor M3 and the transistor M3r are in an on state or the transistor M4 and the transistor M4r are in an on state is tut, the time during which the transistor M3-2b and the transistor M3-2br are in an on state or the transistor M4-2b and the transistor M4-2br are in an on state is 2tut, and the time during which the transistor M3-3b and the transistor M3-3br are in an on state or the transistor M4-3b and the transistor M4-3br are in an on state is 4tut, for example, the second data (a value of a signal of a neuron) at the time when a high-level potential is input to the wiring X1L, a low-level potential is input to the wiring X2L, and a low-level potential is input to the wiring X1L2b, the wiring X2L2b, the wiring X1L3b, and the wiring X2L3b may be defined as not “+1” but a real number such as “+0.1”.
In the semiconductor device of one embodiment of the present invention, the configuration of the circuit MP is not limited to that in
The semiconductor device of one embodiment of the present invention and the operation method of the semiconductor device are not limited to the above. Although the sizes of the transistor M1, the transistor M1r, the transistor M1-2b, the transistor M1-2br, the transistor M1-3b, and the transistor M1-3br of the circuit MP in
Here, the time during which the transistor M3 and the transistor M3r are in an on state or the transistor M4 and the transistor M4r are in an on state is tut, the time during which the transistor M3-2b and the transistor M3-2br are in an on state or the transistor M4-2b and the transistor M4-2br are in an on state is 2tut, and the time during which the transistor M3-3b and the transistor M3-3br are in an on state or the transistor M4-3b and the transistor M4-3br are in an on state is 2tut. That is, in inputting the second data (a value of a signal of a neuron) to the circuit MP, the input time of a high-level potential to one of the wiring X1L and the wiring X2L is tut, the input time of a high-level potential to one of the wiring X1L2b and the wiring X2L2b is 2tut, and the input time of a high-level potential to one of the wiring X1L3b and the wiring X2L3b is 2tut. The circuit MP in
When the potential VDDL is held in the circuit HCS and a current having the current amount of Iut flows between the source and the drain of the transistor M1, one of the transistor M3-3b and the transistor M4-3b is in an on state only for the time 2tut and the other of the transistor M3-3b and the transistor M4-3b is in an off state, so that the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1-3b is 2tut×2Iut=4Qut. Note that the conditions of the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1 and the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1-2b are the same as those of the above-described operation example, and thus the description is omitted.
When the potential VDDL is held in the circuit HCSr and i a current having the current amount of I1 flows between the source and the drain of the transistor M1r, one of the transistor M3-3br and the transistor M4-3br is turned on only for the time 2tut and the other of the transistor M3-3br and the transistor M4-3br is turned off, so that the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1-3br is 2tut×2Iut=4Qut. Note that the conditions of the amount of charge flowing from the wiring OLB to the wiring VEr through the transistor M1r and the amount of charge flowing from the wiring OLB to the wiring VEr through the transistor M1-2br are the same as those of the above-described operation example, and thus the description is omitted.
As described above, the sizes of the transistor M1, the transistor M1r, the transistor M1-2b, the transistor M1-2br, the transistor M1-3b, and the transistor M1-3br and the input time of a high-level potential to each of the wiring X1L, the wiring X2L, the wiring X1L2b, the wiring X2L2b, the wiring X1L3b, and the wiring X2L3b are appropriately changed, whereby the operation can be similar to that of the operation example of the circuit MP shown in
In the semiconductor device of one embodiment of the present invention, the configuration of the circuit MP is not limited to that in
The operation method of the semiconductor device of one embodiment of the present invention is not limited to the above. For example, as described in Operation method example 2, the input period of signals that are input to the wiring X1L, the wiring X2L, the wiring X1L2b, the wiring X2L2b, the wiring X1L3b, and the wiring X2L3b may be divided into a plurality of subperiods in the circuits MP in
In this operation method example, the case is considered where only one circuit MP is electrically connected to the wiring OL and the wiring OLB to avoid complexity of description; however, a plurality of circuits MP may be electrically connected to the wiring OL and the wiring OLB as in the arithmetic circuit 150 in
Although the arithmetic circuit 150 in
Note that this operation method example can be combined with any of the other operation method examples and the like described in this specification as appropriate.
Described here is an operation method of the arithmetic circuit 150 in
As in Operation method example 1 to Operation method example 8, to avoid complexity of description, a current flowing through the wiring OL and the wiring OLB is changed by only one circuit MP electrically connected to the wiring OL and the wiring OLB. The wiring VE and the wiring VEr electrically connected to the circuit MP each supply VSS as a constant voltage to the circuit MP. The circuit ACTF[1] to the circuit ACTF[n] included in the circuit AFP are each the circuit ACTF having a configuration of an integrator circuit (or a current-charge (IQ) converter circuit), for example. The circuit ACTF may have a configuration in which the load LEa and the load LEb in the circuit ACTF[j] in
In the circuit MP in
Note that the sizes, e.g., the W lengths and the L lengths, of the transistor M1, the transistor M1-2x, and the transistor M1-3x are preferably equal to each other. The sizes of the transistor M1-2b, the transistor M1-2x-2b, and the transistor M1-3x-2b are preferably equal to each other. The sizes of the transistor M1-3b, the transistor M1-2x-3b, and the transistor M1-3x-3b are preferably equal to each other.
Furthermore, when the ratios of the W lengths to the L lengths of the transistor M1, the transistor M1-2x, and the transistor M1-3x are each W/L, the ratios of the W lengths to the L lengths of the transistor M1-2b, the transistor M1-2x-2b, and the transistor M1-3x-2b are each preferably 2 W/L and the ratios of the W lengths to the L lengths of the transistor M1-3b, the transistor M1-2x-3b, and the transistor M1-3x-3b are each preferably 4 W/L. That is, the ratios W/L of the W lengths to the L lengths of the transistors (e.g., the transistor M1, the transistor M1-2b, and the transistor M1-3b) whose gates are electrically connected to the holding portions (e.g., the circuit HCS, the circuit HCS-2b, and the circuit HCS-3b) can be increased to be a power of two in accordance with the number of holding portions.
In this specification and the like, unless otherwise specified, the transistor M1, the transistor M1-2x, the transistor M1-3x, the transistor M1-2b, the transistor M1-2x-2b, the transistor M1-3x-2b, the transistor M1-3b, the transistor M1-2x-3b, and the transistor M1-3x-3b in an on state may operate in a saturation region in the end. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in a saturation region. However, one embodiment of the present invention is not limited thereto. These transistors may operate in a linear region so that the amplitude value of a voltage to be supplied is decreased. To reduce the amount of current flowing through these transistors, the above transistors may operate in a subthreshold region. Alternatively, the transistor M1, the transistor M1-2x, the transistor M1-3x, the transistor M1-2b, the transistor M1-2x-2b, the transistor M1-3x-2b, the transistor M1-3b, the transistor M1-2x-3b, and the transistor M1-3x-3b may operate around the boundary between the saturation region and the subthreshold region. Note that in the case where the first data (a weight coefficient) is an analog value, for example, the above transistors may operate in the linear region, the saturation region, and the subthreshold region depending on the cases in accordance with the magnitude of the first data (weight coefficient). Alternatively, the transistor M1, the transistor M1-2x, the transistor M1-3x, the transistor M1-2b, the transistor M1-2x-2b, the transistor M1-3x-2b, the transistor M1-3b, the transistor M1-2x-3b, and the transistor M1-3x-3b may operate in both the linear region and the saturation region, may operate in both the subthreshold region and the linear region, or may operate in both the saturation region and the subthreshold region.
In this specification and the like, unless otherwise specified, the transistor M3, the transistor M3-2x, the transistor M3-3x, the transistor M4, the transistor M4-2x, and the transistor M4-3x in an on state may operate in a linear region in the end. In other words, the gate voltage, the source voltage, and the drain voltage of each of the above transistors may be appropriately biased to voltages in the range where the transistor operates in the linear region. However, one embodiment of the present invention is not limited thereto. For example, the transistor M3, the transistor M3-2x, the transistor M3-3x, the transistor M4, the transistor M4-2x, and the transistor M4-3x in an on state may operate in a saturation region or may operate in a subthreshold region. Alternatively, they may operate around the boundary between the saturation region and the subthreshold region. Alternatively, the transistor M3, the transistor M3-2x, the transistor M3-3x, the transistor M4, the transistor M4-2x, and the transistor M4-3x may operate in both the linear region and the saturation region, may operate in both the saturation region and the subthreshold region, may operate in both the subthreshold region and the linear region, or may operate in the linear region, the saturation region, and the subthreshold region.
Like the circuit HCS included in the circuit MP in
Note that the gates of the transistor M1-2b, the transistor M1-2x-2b, and the transistor M1-3x-2b are electrically connected to the circuit HCS-2b. The gates of the transistor M1-3b, the transistor M1-2x-3b, and the transistor M1-3x-2b are electrically connected to the circuit HCS-3b.
When VDDL held in the circuit HCS is input to the gates of the transistor M1, the transistor M1-2x, and the transistor M1-3x, the amount of current flowing between the sources and the drains of the transistor M1, the transistor M1-2x, and the transistor M1-3x is Iut. Since the ratios of the W lengths to the L lengths of the transistor M1-2b, the transistor M1-2x-2b, and the transistor M1-3x-2b are each twice as high as the ratio of the W length to the L length of the transistor M1, the amount of current flowing between the sources and the drains of the transistor M1-2b, the transistor M1-2x-2b, and the transistor M1-3x-2b is 2Iut when VDDL held in the circuit HCS-2b is input to the gates of the transistor M1-2b, the transistor M1-2x-2b, and the transistor M1-3x-2b. Since the ratios of the W lengths to the L lengths of the transistor M1-3b, the transistor M1-2x-3b, and the transistor M1-3x-3b are each four times as high as the ratio of the W length to the L length of the transistor M1, the amount of current flowing between the sources and the drains of the transistor M1-3b, the transistor M1-2x-3b, and the transistor M1-3x-3b is 4Iut when VDDL held in the circuit HCS-3b is input to the gates of the transistor M1-3b, the transistor M1-2x-3b, and the transistor M1-3x-3b.
The first terminals of the transistor M1, the transistor M1-2x, the transistor M1-3x, the transistor M1-2b, the transistor M1-2x-2b, the transistor M1-3x-2b, the transistor M1-3b, the transistor M1-2x-3b, and the transistor M1-3x-2b are electrically connected to the wiring VE. The gates of the transistor M1, the transistor M1-2x, and the transistor M1-3x are electrically connected to the circuit HCS.
The second terminals of the transistor M1, the transistor M1-2b, and the transistor M1-3b are electrically connected to the first terminal of the transistor M3 and the first terminal of the transistor M4. The second terminals of the transistor M1-2x, the transistor M1-2x-2b, and the transistor M1-2x-3b are electrically connected to the first terminal of the transistor M3-2x and the first terminal of the transistor M4-2x. The second terminals of the transistor M1-3x, the transistor M1-3x-2b, and the transistor M1-3x-3b are electrically connected to a first terminal of the transistor M3-3x and a first terminal of the transistor M4-3x.
The gate of the transistor M3 is electrically connected to the wiring X1L, and the gate of the transistor M4 is electrically connected to the wiring X2L. The gate of the transistor M3-2x is electrically connected to the wiring X1L2x, and the gate of the transistor M4-2x is electrically connected to the wiring X2L2x. The gate of the transistor M3-3x is electrically connected to the wiring X1L3x, and the gate of the transistor M4-3x is electrically connected to the wiring X2L3x.
The second terminals of the transistor M3, the transistor M3-2x, and the transistor M3-3x are electrically connected to the wiring OL, and the second terminals of the transistor M4, the transistor M4-2x, and the transistor M4-3x are electrically connected to the wiring OLB.
Note that in the circuit MP in
The first data (e.g., a weight coefficient here) set in the circuit MP in
Next, the second data (e.g., a value of a signal of a neuron here) input to the circuit MP is described. Assume that, in inputting the second data (a value of a signal of a neuron) to the circuit MP, the input time of a high-level potential to one of the wiring X1L and the wiring X2L is tut, the input time of a high-level potential to one of the wiring X1L2x and the wiring X2L2x is 2tut, and the input time of a high-level potential to one of the wiring X1L3x and the wiring X2L3x is 4tut in the operation. That is, the operation is performed such that when the time during which the transistor M3 and the transistor M3r are in an on state or the transistor M4 and the transistor M4r are in an on state is tut, the time during which the transistor M3-2x and the transistor M3-2xr are in an on state or the transistor M4-2x and the transistor M4-2xr are in an on state is 2tut and the time during which the transistor M3-3x and the transistor M3-3xr are in an on state or the transistor M4-3x and the transistor M4-3xr are in an on state is 4tut.
As described in Operation method example 1 and Operation method example 2, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1, the transistor M1-2b, and the transistor M1-3b is determined by setting the first data (e.g., a weight coefficient here) in the circuit MP and setting the time during which the transistor M3 or the transistor M4 is in an on state. In addition, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1r, the transistor M1-2br, and the transistor M1-3br is determined by setting the first data (a weight coefficient) in the circuit MP and setting the time during which the transistor M3r or the transistor M4r is in an on state.
Similarly, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1-2x, the transistor M1-2x-2b, and the transistor M1-2x-3b and the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1-2xr, the transistor M1-2x-2br, and the transistor M1-2x-3br are also determined by setting the times during which the transistor M3-2x, the transistor M3-2xr, the transistor M4-2x, and the transistor M4-2xr are in an on state. In addition, the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VE through the transistor M1-3x, the transistor M1-3x-2b, and the transistor M1-3x-3b and the amount of charge flowing from the wiring OL or the wiring OLB to the wiring VEr through the transistor M1-3xr, the transistor M1-3x-2br, and the transistor M1-3x-3br are also determined by setting the times during which the transistor M3-3x, the transistor M3-3xr, the transistor M4-3x, and the transistor M4-3xr are in an on state.
Thus, the second data (a value of a signal of a neuron) in the circuit MP in
When the first data (a weight coefficient) and the second data (a value of a signal of a neuron) are determined as described above, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be expressed by the charge amount with which a current flowing from the wiring OL to the circuit MC or the circuit MCr and the charge amount with which a current flowing from the wiring OLB to the circuit MC or the circuit MCr.
Next, a specific operation example of the circuit MP in
The first data (a weight coefficient) of “+7” is set in the circuit MP in advance, for example. At this time, the current of ut flows between the sources and the drains of the transistor M1, the transistor M1-2x, and the transistor M1-3x, the current of 2Iut flows between the sources and the drains of the transistor M1-2b, the transistor M1-2x-2b, and the transistor M1-3x-2b, and the current of 4Iut flows between the sources and the drains of the transistor M1-3b, the transistor M1-2x-3b, and the transistor M1-3x-3b. Meanwhile, the amount of current flowing between the sources and the drains of the transistor M1r, the transistor M1-2xr, the transistor M1-3xr, the transistor M1-2br, the transistor M1-2x-2br, the transistor M1-3x-2br, the transistor M1-3br, the transistor M1-2x-3br, and the transistor M1-3x-3br is 0.
In the case where “+7” is input to the circuit MP as the second data (a value of a signal of a neuron), the transistor M3 is in an on state only for the time tut and the transistor M4 is in an off state, so that the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1, the transistor M1-2b, and the transistor M1-3b is tut×Iut+tut×2Iut+tut×4Iut=7tut×Iut. Note that tut×Iut=Qut is satisfied here. In addition, the transistor M3-2x is in an on state only for the time 2tut and the transistor M4-2x is in an off state, so that the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1-2x, the transistor M1-2x-2b, and the transistor M1-2x-3b is 2tut×Iut+2tut×2Iut+2tut×4Iut=14tut×Iut. In addition, the transistor M3-3x is in an on state only for the time 4tut and the transistor M4-3x is in an off state, so that the amount of charge flowing from the wiring OL to the wiring VE through the transistor M1-3x, the transistor M1-3x-2b, and the transistor M1-3x-3b is 4tut×Iut+4tut×2Iut+4tut×4Iut=28tut×Iut. Thus, the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC is 7Qut+14Qut+28Qut=49Qut. Meanwhile, the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is 0 because the transistor M1r, the transistor M1-2xr, the transistor M1-3xr, the transistor M1-2br, the transistor M1-2x-2br, the transistor M1-3x-2br, the transistor M1-3br, the transistor M1-2x-3br, and the transistor M1-3x-3br are in an off state.
In the case where “−7” is input to the circuit MP as the second data (a value of a signal of a neuron), electrical continuity is established between the wiring OLB and the circuit MC and between the wiring OL and the circuit MCr, and electrical continuity is not established between the wiring OLB and the circuit MCr and between the wiring OL and the circuit MC; hence, the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC is 7Qut+14Qut+28Qut=49Qut and the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr is 0.
Here, the first data (a weight coefficient) of “−7” is set in the circuit MP in advance, for example. At this time, the current of ut flows between the sources and the drains of the transistor M1r, the transistor M1-2xr, and the transistor M1-3xr; the current of 2Iut flows between the sources and the drains of the transistor M1-2br, the transistor M1-2x-2br, and the transistor M1-3x-2br; and the current of 4Iut flows between the sources and the drains of the transistor M1-3br, the transistor M1-2x-3br, and the transistor M1-3x-3br. Meanwhile, the amount of current flowing between the sources and the drains of the transistor M1, the transistor M1-2x, the transistor M1-3x, the transistor M1-2b, the transistor M1-2x-2b, the transistor M1-3x-2b, the transistor M1-3b, the transistor M1-2x-3b, and the transistor M1-3x-3b is 0.
In the case where “+7” is input to the circuit MP as the second data (a value of a signal of a neuron), the transistor M3r is in an on state only for the time tut and the transistor M4r is in an off state, so that the amount of charge flowing from the wiring OLB to the wiring VEr through the transistor M1r, the transistor M1-2br, and the transistor M1-3br is tut×Iut+tut×2Iut+tut×4Iut=7tut×Iut. Note that tut×Iut=Qut is satisfied here. In addition, the transistor M3-2xr is in an on state only for the time 2tut and the transistor M4-2xr is in an off state, so that the amount of charge flowing from the wiring OL to the wiring VEr through the transistor M1-2xr, the transistor M1-2x-2br, and the transistor M1-2x-3br is 2tut×Iut+2tut×2Iut+2tut×4Iut=14tut×Iut. In addition, the transistor M3-3xr is in an on state only for the time 4tut and the transistor M4-3xr is in an off state, so that the amount of charge flowing from the wiring OLB to the wiring VEr through the transistor M1-3xr, the transistor M1-3x-2br, and the transistor M1-3x-3br is 4tut×Iut+4tut×2Iut+4tut×4Iut=28tut×Iut. Thus, the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is 7Qut+14Qut+28Qut=49Qut. Meanwhile, the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC is 0 because the transistor M1, the transistor M1-2x, the transistor M1-3x, the transistor M1-2b, the transistor M1-2x-2b, the transistor M1-3x-2b, the transistor M1-3b, the transistor M1-2x-3b, and the transistor M1-3x-3b are in an off state.
In the case where “−7” is input to the circuit MP as the second data (a value of a signal of a neuron), electrical continuity is established between the wiring OLB and the circuit MC and between the wiring OL and the circuit MCr, and electrical continuity is not established between the wiring OLB and the circuit MCr and between the wiring OL and the circuit MC; hence, the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC is 7Qut+14Qut+28Qut=49Qut and the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr is 0.
Thus, by setting the positive first data (a weight coefficient) of any one of seven levels “+1” to “+7” in the circuit MP and selecting one or more transistors to be turned on from the transistor M3, the transistor M3-2x, and the transistor M3-3x included in the circuit MP in accordance with the positive second data (a value of a signal of a neuron), the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC can be any one of “Qut” to “49Qut” in steps of Qut. Note that the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr is 0 at this time. In addition, by setting the negative first data (a weight coefficient) of any one of seven levels “−7” to “−1” in the circuit MP and selecting one or more transistors to be turned on from the transistor M3r, the transistor M3-2xr, and the transistor M3-3xr included in the circuit MP in accordance with the positive second data (a value of a signal of a neuron), the amount of charge flowing from the wiring OLB to the wiring VEr through the circuit MCr can be any one of “Qut” to “49Qut” in steps of Qut. Note that the amount of charge flowing from the wiring OL to the wiring VE through the circuit MC is 0 at this time.
In addition, by setting the positive first data (a weight coefficient) of any one of seven levels “+1” to “+7” in the circuit MP and selecting one or more transistors to be turned on from the transistor M4, the transistor M4-2x, and the transistor M4-3x included in the circuit MP in accordance with the negative second data (a value of a signal of a neuron), the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC can be any one of “Qut” to “49Qut” in steps of Qut. Note that the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr is 0 at this time. In addition, by setting the negative first data (a weight coefficient) of any one of seven levels “−7” to “−1” in the circuit MP and selecting one or more transistors to be turned on from the transistor M4r, the transistor M4-2xr, and the transistor M4-3xr included in the circuit MP in accordance with the negative second data (a value of a signal of a neuron), the amount of charge flowing from the wiring OL to the wiring VEr through the circuit MCr can be any one of “Qut” to “49Qut” in steps of Qut. Note that the amount of charge flowing from the wiring OLB to the wiring VE through the circuit MC is 0 at this time.
In the case where the first data (a weight coefficient) of “0” is set in the circuit MP in advance, the transistor M1, the transistor M1-2x, the transistor M1-3x, the transistor M1-2b, the transistor M1-2x-2b, the transistor M1-3x-2b, the transistor M1-3b, the transistor M1-2x-3b, the transistor M1-3x-3b, the transistor M1r, the transistor M1-2xr, the transistor M1-3xr, the transistor M1-2br, the transistor M1-2x-2br, the transistor M1-3x-2br, the transistor M1-3br, the transistor M1-2x-3br, and the transistor M1-3x-3br are in an off state. Thus, a current does not flow from the wiring OL or the wiring OLB to the wiring VE through the circuit MC, and a current does not flow from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr. In other words, the amount of charge flowing through the wiring OL and the wiring OLB is 0.
In the case where the second data (a value of a signal of a neuron) of “0” is input to the circuit MP, the transistor M3, the transistor M3-2x, the transistor M3-3x, the transistor M4, the transistor M4-2x, the transistor M4-3x, the transistor M3r, the transistor M3-2xr, the transistor M3-3xr, the transistor M4r, the transistor M4-2xr, and the transistor M4-3xr are in an off state. Thus, a current does not flow from the wiring OL or the wiring OLB to the wiring VE through the circuit MC, and a current does not flow from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr. In other words, the amount of charge flowing through the wiring OL and the wiring OLB is 0.
Here, attention is focused on the integrator circuit of the circuit ACTF. When a current flows from the wiring OL or the wiring OLB to the wiring VE through the circuit MC or when a current flows from the wiring OL or the wiring OLB to the wiring VEr through the circuit MCr, the switch SWO and the switch SWOB are turned on and the switch SWI, the switch SWIB, the switch SWL, the switch SWLB, the switch SWH, and the switch SWHB are turned off in
The following table shows the charge amount QOL supplied through the wiring OL and the charge amount QOLB supplied through the wiring OLB in the case of the above operation example where the first data (a weight coefficient) is any one of “−7” to “+7” except for “0” and the second data (a value of a signal of a neuron) is any one of “−7” to “+7” except for “0”. When at least one of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is “0”, QOL=0 and QOLB=0 are satisfied.
By setting the first data (a weight coefficient) and the second data (a value of a signal of a neuron) as described above, the charge amount QOL with which a current flows from the wiring OL to the circuit MC or the circuit MCr and the charge amount QOLB with which a current flows from the wiring OLB to the circuit MC or the circuit MCr are determined in accordance with the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron). In the case where the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a positive value, a current flows from the wiring OL to the circuit MC or the circuit MCr, and in the case where the result of the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a negative value, a current flows from the wiring OLB to the circuit MC or the circuit MCr. That is, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be calculated from the charge amount QOL and the charge amount QOLB. For example, in the case where the first data (a weight coefficient) is any one of “−7” to “+7”, the second data (a value of a signal of a neuron) is any one of “−7” to “+7”, and the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a positive number, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be calculated from the charge amount QOL by replacing Qut with “+1” in the charge amount QOL with which a current flows from the wiring OL to the circuit MC or the circuit MCr in the above table. Alternatively, for example, in the case where the first data (a weight coefficient) is any one of “−7” to “+7”, the second data (a value of a signal of a neuron) is any one of “−7” to “+7”, and the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) is a negative number, the product of the first data (a weight coefficient) and the second data (a value of a signal of a neuron) can be calculated from the charge amount QOLB by replacing Qut with “−1” in the charge amount QOLB with which a current flows from the wiring OLB to the circuit MC or the circuit MCr in the above table.
One embodiment of the present invention is not limited to the above definition. Although the second data (a value of a signal of a neuron) is defined above as a positive multilevel value, a negative multilevel value, or 0, the second data (a value of a signal of a neuron) can be processed as an analog value by using not a discrete value but a continuous value as the input period (by setting the input period to a×tut, where a is a positive real number).
In the semiconductor device of one embodiment of the present invention, the configuration of the circuit MP is not limited to that in
The operation method of the semiconductor device of one embodiment of the present invention is not limited to the above. For example, as described in Operation method example 2, the input period of signals that are input to the wiring X1L, the wiring X2L, the wiring X1L2b, the wiring X2L2b, the wiring X1L3b, and the wiring X2L3b may be divided into a plurality of subperiods in the circuit MP in
In this operation method example, the case is considered where only one circuit MP is electrically connected to the wiring OL and the wiring OLB to avoid complexity of description; however, a plurality of circuits MP may be electrically connected to the wiring OL and the wiring OLB as in the arithmetic circuit 150 in
Although the arithmetic circuit 150 in
Note that this operation method example can be combined with any of the other operation method examples and the like described in this specification as appropriate.
Note that this embodiment can be combined with any of the other embodiments in this specification as appropriate.
As an example, this embodiment describes a structure example of a semiconductor device for conducting arithmetic operation performed in a convolutional neural network (CNN). Note that as the semiconductor device, the semiconductor device described in any of the above embodiments can be used.
A CNN is one of calculation models used for feature extraction of an image or the like.
The convolutional layer CL has a function of performing convolutional processing on the image data. The convolutional processing is performed by repeating product-sum operation using a partial region of the image data and the filter value of a weight filter. By the convolution in the convolutional layer CL, a feature of an image is extracted.
For the convolutional processing, one or a plurality of weight filters can be used. In the case of using a plurality of weight filters, a plurality of features of the image data can be extracted.
For example, arithmetic operation with an activation function may be performed on the image data Da, Db, and Dc that have been subjected to convolution. As the activation function, a ReLU (Rectified Linear Units) or the like can be used, for example. A ReLU is a function that outputs “0” when an input value is negative and outputs the input value as it is when the input value is greater than or equal to “0”. Alternatively, as the activation function, a sigmoid function, a tan h function, or the like can be used as well.
The image data Da, Db, and Dc that have been subjected to the convolution (it does not matter whether arithmetic operation with an activation function has been performed) are output to the pooling layer PL, for example. The pooling layer PL has a function of performing pooling on the image data input from the convolutional layer CL. Pooling is processing in which the image data is partitioned into a plurality of regions and predetermined data extracted from each of the regions are arranged in a matrix to form new data. By the pooling, the image data can be reduced while the features extracted by the convolutional layer CL remain. As the pooling processing, max pooling, average pooling, Lp pooling, or the like can be used.
In the CNN, feature extraction is performed using the above convolutional processing and pooling processing, for example. Note that the CNN may include a plurality of convolutional layers CL and/or a plurality of pooling layers PL.
Although
The fully connected layer FCL has a function of determining an image using the image data obtained through convolution and pooling, for example. The fully connected layer FCL has a structure in which all nodes in one layer are connected to all nodes in the next layer. The image data output from the convolutional layer CL or the pooling layer PL is a two-dimensional feature map and is unfolded into a one-dimensional feature map when input to the fully connected layer FCL. Then, data OPD obtained as a result of inference by the fully connected layer FCL is output.
Note that the structure of the CNN is not limited to the structure in
In the case of classifying images using the output data from the fully connected layer FCL, an output layer electrically connected to the fully connected layer FCL may be provided. The output layer can output a classification class using a softmax function or the like as a likelihood function.
The CNN can perform supervised learning using image data as learning data and teacher data. In the supervised learning, a backpropagation method can be used, for example. Owing to the learning in the CNN, the filter value of the weight filter, the weight coefficient of the fully connected layer, or the like can be optimized.
Next, a specific example of the convolutional processing performed in the convolutional layer CL is described.
The convolution is performed by the product-sum operation using the image data g and the filter value of a weight filter.
In the case of performing feature extraction by convolution, data showing certain features (referred to as feature data) can be stored as the filter value fa[1,1] to the filter value fa[t,s]. Then, in the feature extraction, the feature data and image data are compared with each other. In addition, in the case of performing image processing such as edge processing or blurring processing by convolution, parameters necessary for the image processing can be stored as the filter value fa[1,1] to the filter value fa[t,s]. As an example, the operation in the case of performing feature extraction is described in detail below.
After that, the above product-sum operation is sequentially performed also in other pixel regions. Specifically, for example, the filter processing is performed on a pixel region P[1,2] whose corners are the pixel pix[1,2], the pixel pix[1,s+1], the pixel pix[t,2], and the pixel pix[t,s+1] to obtain data Da[1,2], as illustrated in
Then, data Da[1,m−s+1] is obtained from a pixel region P[1,m−s+1] whose corners are the pixel pix[1,m−s+1], the pixel pix[1,m], the pixel pix[t,m−s+1], and the pixel pix[t,m]. After the data Da is obtained in each of the pixel regions in one row, i.e., the pixel region P[1,1] to the pixel region P[1,m−s+1], the pixel region P is moved by one pixel row and the data Da is sequentially obtained in the pixel row in a similar manner, for example.
When the above operation is repeated and data Da[n−t+1,m−s+1] is obtained from a pixel region P[n−t+1,m−s+1] whose corners are the pixel pix[n−t+1,m−s+1], the pixel pix[n−t+1,m], the pixel pix[n,m−s+1], and the pixel pix[n,m], the filter processing using the filter fila on all pixel regions P is completed.
In such a manner, the pixel region P having pixels arranged in a matrix of t rows and s columns is selected from the pixel pix[1,1] to the pixel pix[n,m] and the filter processing using the filter fila is performed on the pixel region P. Data Da[x,y] obtained by performing the filter processing using the filter fila on a pixel region P whose corners are the pixel pix[x,y] (here, x is an integer greater than or equal to 1 and less than or equal to n−t+1, and y is an integer greater than or equal to 1 and less than or equal to m−s+1), the pixel pix[x,y+s−1], the pixel pix[x+t−1,y], and the pixel pix[x+t−1,y+s−1] can be expressed by the following formula.
As described above, the data Da[1,1] to Da[n−t+1,m−s+1] can be obtained when the filter processing using the filter fila is performed on all the pixel regions P in t rows and s columns that can be selected from the pixel pix[1,1] to the pixel pix[n,m]. Then, the data Da[1,1] to the data Da[n−t+1,m−s+1] are arranged in a matrix in accordance with the addresses, so that a feature map (a depth map depending on the case) illustrated in
In the above manner, the convolutional processing is performed by the product-sum operation using the image data and the filter values to extract the feature of an image.
Note that in the case where a plurality of filters fil are provided in the convolutional layer CL as illustrated in
Although described here is an example in which the pixel region P is moved by one pixel column and one pixel row, a moving distance (sometimes referred to as a stride) of the pixel region P can be set freely. For example, the pixel region P may be moved by two rows and two columns or may be moved by one row and three columns. As another example, the pixel region P may be moved in the column direction by a number greater than or equal to the number of columns in the pixel region P and/or moved in the row direction by a number greater than or equal to the number of rows in the pixel region P. That is, the moving distance may be set so that the moved pixel region P does not overlap the pixel region P at the original position.
The size of the image data can be, for example, 8K UHD (7680×4320), 4K UHD (3840×2160), FHD (1920×1080), HD (1280×720), SD (720×480), or the like. Moreover, as for the size of the image data, the number of rows may be a number greater than 0, a number greater than or equal to 50, a number greater than or equal to 100, or a number greater than or equal to 500; and the number of columns may be a number greater than 0, a number greater than or equal to 50, a number greater than or equal to 100, or a number greater than or equal to 500. Note that the lower limit of the number of rows and the lower limit of the number of columns can be individually and freely selected.
As for the size of a filter (the range of a pixel region) used in convolutional processing, for example, the number of rows may be a number greater than 0, a number greater than or equal to 3, a number greater than or equal to 5, a number greater than or equal to 10, a number greater than or equal to 50, or a number greater than or equal to 100; and the number of columns may be a number greater than 0, a number greater than or equal to 3, a number greater than or equal to 5, a number greater than or equal to 10, a number greater than or equal to 50, or a number greater than or equal to 100. Note that the lower limit of the number of rows and the lower limit of the number of columns can be individually and freely selected.
Next, the case where the above-described convolutional processing is performed in the semiconductor device described in the above embodiment is described.
Here, as an example, an operation example where the arithmetic circuit 110 in
Moreover, the convolutional processing here is performed using u weight filters (u is an integer greater than or equal to 1). Thus, the u weight filters are referred to as a filter fil1 to a filter filu.
In the arithmetic circuit 110 in
Although [x,y] is added as the address to the reference numerals of the circuits MP in
In the arithmetic circuit 110 in
The wiring WLS[1] to the wiring WLS[t×s] are electrically connected to the circuit WLD. The wiring XLS[1] to the wiring WLS[t×s] are electrically connected to the circuit XLD. Note that the description of the circuit WLD and the circuit XLD in
In particular, the circuit XLD of the arithmetic circuit 110 in
In the arithmetic circuit 110 in
The wiring IL[1] to the wiring IL[u] and the wiring ILB[1] to the wiring ILB[u] are electrically connected to the circuit ILD. The wiring OL[1] to the wiring OL[u] and the wiring OL[1] to the wiring OL[u] are electrically connected to the circuit AFP. Note that the description of the circuit ILD and the circuit AFP in
Specifically, the wiring OL[1] and the wiring OLB[1] are electrically connected to the circuit ACTF[1] included in the circuit AFP. The wiring OL[h] and the wiring OLB[h] are electrically connected to the circuit ACTF[h] included in the circuit AFP. The wiring OL[u] and the wiring OLB[u] are electrically connected to the circuit ACTF[u] included in the circuit AFP. Note that the description of the circuit ACTF[1] to the circuit ACTF[n] in
Next, the circuit MP included in the array portion ALP of the arithmetic circuit 110 in
In the circuit MP of the array portion ALP, the filter value of a weight filter is held, for example. The filter value of the weight filter can be, for example, a binary value of “0” and “+1”, a binary value of “−1” and “+1”, a ternary value of “−1”, “0”, and “+1”, a multilevel value greater than a ternary value, or an analog value, as described in the above embodiment.
Here, assume that filter values included in the filter fil1 are held in the circuits MP in the first column of the array portion ALP, filter values included in the filter filh are held in the circuits MP in the h-th column of the array portion ALP, and filter values included in the filter filu are held in the circuits MP in the u-th column of the array portion ALP.
For example, given that the filter value in a v-th row and a w-th column (here, v is an integer greater than or equal to 1 and less than or equal to t, and w is an integer greater than or equal to 1 and less than or equal to s) of the filter fil1 is f1[v,w], f1[1,1] is held in the circuit MP in the first row and the first column of the array portion ALP, f1[1,s] is held in the circuit MP in the s-th row and the first column of the array portion ALP, f1[t,1] is held in the circuit MP in the (t−1)s+1-th row and the first column of the array portion ALP, and f1[t,s] is held in the circuit MP in the t×s-th row and the first column of the array portion ALP. As a similar example, given that the filter value in the v-th row and the w-th column of the filter filh is fh[v,w], fh[1,1] is held in the circuit MP in the first row and the h-th column of the array portion ALP, fh[1,s] is held in the circuit MP in the s-th row and the h-th column of the array portion ALP, fh[t, 1] is held in the circuit MP in the (t−1)s+1-th row and the h-th column of the array portion ALP, and fh[t,s] is held in the circuit MP in the t×s-th row and the h-th column of the array portion ALP. As a similar example, given that the filter value in the v-th row and the w-th column of the filter filu is fu[v,w], fu[1,1] is held in the circuit MP in the first row and the u-th column of the array portion ALP, fu[1,s] is held in the circuit MP in the s-th row and the u-th column of the array portion ALP, fu[t,1] is held in the circuit MP in the (t−1)s+1-th row and the u-th column of the array portion ALP, and fu[t,s] is held in the circuit MP in the t×s-th row and the u-th column of the array portion ALP. That is, the filter filh of v rows and w columns has a total of v×w values, for example. These values are stored in a total of v×w circuits MP arranged in the vertical direction in the h-th column. Note that in the case where the number of columns of the circuits MP in the array portion ALP is larger than the number of filters fil, a value of 0 is held in the circuits MP in a surplus column. Specifically, a voltage that does not allow a current to flow from the circuit MP to the wiring IL and the wiring ILB is held. Thus, a current is not output from the circuit MP to the wiring IL and the wiring ILB, so that power consumption can be reduced.
When the filter value of the weight filter is held in each of the circuits MP in the array portion ALP, t×s image data to be subjected to convolutional processing among g[1,1] to g[n,m] are input as image data to the wiring XLS[1] to the wiring XLS[t×s].
For example, g[1,1] to g[1,s] included in the pixel region P[1,1] of the image data targeted for convolutional processing are input to the wiring XLS[1] to the wiring XLS[s], respectively. Moreover, g[t,1] to g[t,s] are input to the wiring XLS[(t−1)s+1] to the wiring XLS[t×s], respectively. In other words, the image data of the pixel region P[1,1] illustrated in
As described in the above embodiment, when the second data (image data in this description) is input from the wiring XLS while the first data (a filter value in this description) is held in the circuit MP, product-sum operation of the first data and the second data is performed. The result of the product-sum operation is determined in accordance with a difference in the amount of current flowing through the wiring OL and the wiring OLB.
Accordingly, in the first column of the array portion ALP, product-sum operation of image data included in the pixel region P[1,1] of the image data and the weight filter fil1 (f1[1,1] to f1[t,s]) is performed. Specifically, a current flows to the circuit ACTF[1] from the circuits MP positioned in the first column of the array portion ALP through the wiring OL[1] and the wiring OLB[1]. Given that the result of the product-sum operation is the data D1[1,1], the data D1[1,1] has a value corresponding to the difference in amount of current flowing through the wiring OL[1] and the wiring OLB[1]. The data D1[1,1] may be subjected to arithmetic operation with an activation function by a circuit included in the circuit ACTF[1].
Similarly, in the h-th column of the array portion ALP, product-sum operation of image data included in the pixel region P[1,1] of the image data and the weight filter filh (fh[1,1] to fh[t,s]) is performed. Given that the result of the product-sum operation is the data Dh[1,1], the data Dh[1,1] has a value corresponding to the difference in amount of current flowing through the wiring OL[h] and the wiring OLB[h]. Moreover, in the u-th column of the array portion ALP, product-sum operation of image data included in the pixel region P[1,1] of the image data and the weight filter filu (fu[1,1] to fu[t,s]) is performed. Given that the result of the product-sum operation is the data Du[1,1], the data Du[1,1] has a value corresponding to the difference in amount of current flowing through the wiring OL[u] and the wiring OLB[u].
The data D1[1,1] to the data Du[1,1] can each be represented by Formula (4.2). By inputting one set of image data for a plurality of weight filters in this manner, a plurality of product-sum operations can be performed concurrently. Thus, power consumption can be reduced, and arithmetic operation can be performed at high speed.
In the arithmetic circuit 110 illustrated in
For example, the arithmetic circuit 110 illustrated in
For example, when first product-sum operation is performed, the circuit XLD outputs g[1,1] to g[t,s] as image data included in the pixel region P[1,1] to the wiring XLS[1] to the wiring XLS[t×s], respectively. Thus, the arithmetic circuit 110 generates the data Dh[1,1], which is the result of the product-sum operation of the filter filh and g[1,1] to g[t,s], in the h-th column of the array portion ALP. At the same time, the data D1[1,1], which is the result of the product-sum operation of the weight filter fil1 and g[1,1] to g[t,s], is generated in the first column of the array portion ALP, and the data Du[1,1], which is the result of the product-sum operation of the filter filu and g[1,1] to g[t,s], is generated in the u-th column of the array portion ALP. Note that
Then, when second product-sum operation is performed, the circuit XLD outputs g[1,2] to g[t,s+1] as image data included in the pixel region P[1,2] to the wiring XLS[1] to the wiring XLS[t×s], respectively. Thus, the arithmetic circuit 110 generates the data Dh[1,2], which is the result of the product-sum operation of the filter filh and g[1,2] to g[t,s+1], in the h-th column of the array portion ALP. Similarly, the arithmetic circuit 110 generates the data D1[1,2], which is the result of the product-sum operation of the weight filter fil1 and g[1,2] to g[t,s+1], in the first column of the array portion ALP, and the arithmetic circuit 110 generates the data Du[1,2], which is the result of the product-sum operation of the filter filu and g[1,2] to g[t,s+1], in the u-th column of the array portion ALP.
That is, by changing the pixel region output from the circuit XLD every time one product-sum operation is performed, the results of the product-sum operations of different pixel regions and the filter fil1 to the filter filu can be output. Here, when all of the pixel region P[1,1] to the pixel region P[n-s+1,m-t+1] that the image data g[1,1] to g[n,m] can have are sequentially output from the circuit XLD, convolutional processing with the filter fil1 to the filter filu can be performed on the pixel region P[1,1] to the pixel region P[n−s+1,m−t+1]. Thus, the arithmetic circuit 110 generates the data D1[1,1] to the data D1[n−s+1,m−t+1], which are the results of the product-sum operation of the pixel region P[1,1] to the pixel region P[n−s+1,m−t+1] and the filter fil1, in the first column of the array portion ALP. Similarly, the arithmetic circuit 110 generates the data Dh[1,1] to the data Dh[n−s+1,m−t+1], which are the results of the product-sum operation of the pixel region P[1,1] to the pixel region P[n−s+1,m−t+1] and the filter filh, in the h-th column of the array portion ALP, and generates the data Du[1,1] to the data Du[n−s+1,m−t+1], which are the results of the product-sum operation of the pixel region P[1,1] to the pixel region P[n−s+1,m−t+1] and the filter filu, in the u-th column of the array portion ALP.
Accordingly, convolutional processing on g[1,1] to g[n,m] included in the image data can be performed, as in a manner similar to that of the processing illustrated in
Note that the image data g[1,1] to g[n,m] discussed in this embodiment may be zero-padded data. Using zero-padded data increases the number of arithmetic operations, so that a feature can be extracted in a portion around the image data.
Note that in the semiconductor device described in the above embodiment, the second data transmitted from the circuit XLD can be a negative value, “0”, or a positive value. Thus, when image data is transmitted as the second data, “0” can be a reference value for the image data. For example, in the case of grayscale, the minimum value (a negative value) can be black, the maximum value (a positive value) can be a white, and gray in the middle can be “0”. Alternatively, when image data is transmitted as the second data, “0” can be the minimum value or the maximum value of the image data. For example, in the case of a generally dark image, “0” can be black and the maximum value (a positive value) can be white. As a result, the use of a negative value can be eliminated. In that case, a circuit such as one illustrated in
The second data (image data) transmitted from the circuit XLD can be treated as a multilevel value or an analog value by the method described in the above embodiment, for example, by using the circuit MP illustrated in any of
The above description shows an example where the value of the weight filter is held in the circuit MP of the array portion ALP in the arithmetic circuit 110, image data is input to the wiring XLS[1] to the wiring XLS[t×s] from the circuit XLD, and convolutional processing is performed on the image data; however, the operation method of the semiconductor device of one embodiment of the present invention is not limited thereto. For example, in the case where convolutional processing is performed in the arithmetic circuit 110, image data may be held in the circuit MP of the array portion ALP in the arithmetic circuit 110, the value of the weight filter may be input to the wiring XLS[1] to the wiring XLS[t×s] from the circuit XLD, and arithmetic operation may be performed.
Thus, the arithmetic circuit 110 in
As described above, image data included in an image subjected to convolutional processing are held in the circuits MP of the array portion ALP.
Here, assume that the image data g[1,1] to g[t,s] included in the pixel region P[1,1] are held in the circuits MP in the first column of the array portion ALP, the image data included in the H-th pixel region (denoted as PH in
For example, g[1,1] is held in the circuit MP in the first row and the first column of the array portion ALP, g[1,s] is held in the circuit MP in the s-th row and the first column of the array portion ALP, g[t,1] is held in the circuit MP in the (t−1)s+1-th row and the first column of the array portion ALP, and g[t,s] is held in the circuit MP in the t×s-th row and the first column of the array portion ALP. As a similar example, g[n−t+1,m−s+1] is held in the circuit MP in the first row and the U-th column of the array portion ALP, g[n−t+1,m] is held in the circuit MP in the s-th row and the U-th column of the array portion ALP, g[n,m−s+1] is held in the circuit MP in the (t−1)s+1-th row and the U-th column of the array portion ALP, and g[n,m] is held in the circuit MP in the t×s-th row and the U-th column of the array portion ALP.
When image data is held in each of the circuits MP of the array portion ALP, f1[1,1] to f1[t,s] are input to the wiring XLS[1] to the wiring XLS[t×s], respectively, as filter values included in the filter fil1 used for convolutional processing.
For example, f1[1,1] to f1[1,s] included in the filter fil1 used for convolutional processing are input to the wiring XLS[1] to the wiring XLS[s], respectively. Moreover, f1[t,1] to f1[t,s] are input to the wiring XLS[(t−1)s+1] to the wiring XLS[t×s], respectively. In other words, the filter values included in the filter fil1 used for the convolutional processing in
As described in the above embodiment, when the second data (a filter value in this description) is input from the wiring XLS while the first data (image data in this description) is held in the circuit MP, product-sum operation of the first data and the second data is performed. The result of the product-sum operation is determined in accordance with a difference in the amount of current flowing through the wiring OL and the wiring OLB.
Accordingly, in the first column of the array portion ALP, product-sum operation of image data included in the pixel region P[1,1] of the image data and the weight filter fil1 (f1[1,1] to f1[t,s]) is performed. Specifically, a current flows to the circuit ACTF[1] from the circuits MP positioned in the first column of the array portion ALP through the wiring OL[1] and the wiring OLB[1]. Given that the result of the product-sum operation is the data D1[1,1], the data D1[1,1] has a value corresponding to the difference in amount of current flowing through the wiring OL[1] and the wiring OLB[1].
Similarly, in the H-th column of the array portion ALP, product-sum operation of image data included in the pixel region PH of the image data and the weight filter fil1 (f1[1,1] to f1[t,s]) is performed. Given that the result of the product-sum operation is the data D1[PH], the data D1[PH] has a value corresponding to the difference in amount of current flowing through the wiring OL[H] and the wiring OLB[H]. Moreover, in the U-th column of the array portion ALP, product-sum operation of image data included in the pixel region P[n−t+1,m−s+1] of the image data and the weight filter fil1 (f1[1,1] to f1[t,s]) is performed. Given that the result of the product-sum operation is the data D1[n−t+1,m−s+1], the data D1[n−t+1,m−s+1] has a value corresponding to the difference in amount of current flowing through the wiring OL[j] and the wiring OLB[j].
The data D1[1,1] to the data D1[n−t+1,m−s+1] can each be represented by Formula (4.2).
In the arithmetic circuit 110 illustrated in
For example, the arithmetic circuit 110 illustrated in
For example, when first product-sum operation is performed, the circuit XLD outputs f1[1,1] to f1[t,s] as the filter values included in the weight filter fil1 to the wiring XLS[1] to the wiring XLS[t×s], respectively. Thus, the arithmetic circuit 110 generates the data D1[PH], which is the result of the product-sum operation of the filter fil1 and the image data included in the pixel region PH, in the H-th column of the array portion ALP. At the same time, the data D1[1,1], which is the result of the product-sum operation of the weight filter fil1 and g[1,1] to g[t,s], is generated in the first column of the array portion ALP, and the data D1[n−t+1,m−s+1], which is the result of the product-sum operation of the filter fil1 and g[n−t+1,m−s+1] to g[n,m], is generated in the U-th column of the array portion ALP.
Then, when second product-sum operation is performed, the circuit XLD outputs f2[1,1] to f2[t,s] as the filter values included in the weight filter fil2 (not illustrated) to the wiring XLS[1] to the wiring XLS[t×s], respectively. Thus, the arithmetic circuit 110 generates the data D2[PH], which is the result of the product-sum operation of the filter fil2 and the image data included in the pixel region PH, in the H-th column of the array portion ALP. Similarly, the arithmetic circuit 110 generates the data D2[1,1], which is the result of the product-sum operation of the weight filter fil2 and g[1,1] to g[t,s], in the first column of the array portion ALP, and the arithmetic circuit 110 generates the data D2[n−t+1,m−s+1], which is the result of the product-sum operation of the filter fil2 and g[n−t+1,m−s+1] to g[n,m], in the U-th column of the array portion ALP.
That is, by changing the weight filter output from the circuit XLD every time one product-sum operation is performed, the results of the product-sum operations of different weight filters and the pixel region P[1,1] to the pixel region P[n−s+1,m−t+1] can be output. Here, by outputting the weight filters fil1 to filu sequentially from the circuit XLD, convolutional processing with the filter fil1 to the filter filu can be performed on the pixel region P[1,1] to the pixel region P[n−s+1,m−t+1]. Thus, the arithmetic circuit 110 generates the data D1[1,1] to the data Du[1,1], which are the results of the product-sum operation of the pixel region P[1,1] and the filter fil1 to the filter filu, in the first column of the array portion ALP. Similarly, the arithmetic circuit 110 generates the data D1[PH] to the data Du[PH], which are the results of the product-sum operation of the pixel region PH and the filter fil1 to the filter filu, in the H-th column of the array portion ALP, and generates the data D1[n−s+1,m−t+1] to the data Du[n−s+1,m−t+1], which are the results of the product-sum operation of the pixel region P[n−s+1,m−t+1] and the filter fil1 to the filter filu, in the U-th column of the array portion ALP.
Accordingly, convolutional processing on g[1,1] to g[n,m] included in the image data can be performed, as in a manner similar to that of the processing illustrated in
In the above operation example, the operation of performing convolutional processing using the arithmetic circuit 110 is described; convolutional processing on images can also be performed using the arithmetic circuit 120, the arithmetic circuit 130, the arithmetic circuit 140, the arithmetic circuit 150, the arithmetic circuit 160, and the arithmetic circuit 170.
In the above-described arithmetic circuit, the filter value of the weight filter (or image data) may be held in the circuit MP by the method of setting the amount of current flowing between the source and the drain of the transistor M1, which is described in Embodiment 1, the method using an SRAM or a NOSRAM described in Embodiment 2, or the like.
Arithmetic operation such as convolutional processing and a neural network can also be performed using a circuit other than the arithmetic circuits described in the above embodiments and the circuits MP included in the arithmetic circuits. Described here is a circuit that is other than the circuits discussed in the above embodiments and can perform arithmetic operation such as convolutional processing and a neural network.
In the circuit MP in
In the circuit MC of the circuit MP in
The wiring X1L and the wiring X2L illustrated in
The circuit MCr of the circuit MP in
For the structures of the transistor M3, the transistor M4, the transistor M8, the transistor M3r, the transistor M4r, and the transistor M8r, the description of the transistor M3, the transistor M4, the transistor M8, the transistor M3r, the transistor M4r, and the transistor M8r, which is mentioned elsewhere, is referred to.
Here, the wiring VL and the wiring VLr each function as a wiring for supplying a constant voltage VCNS. VCNS can be, for example, aground potential (GND) or a low potential in a range where the load circuit LC and a load circuit LCr operate normally.
The load circuit LC and the load circuit LCr are each a circuit capable of changing a resistance between a first terminal and a second terminal, for example. By changing the resistance between the first terminal and the second terminal of each of the load circuit LC and the load circuit LCr, the amount of current flowing between the first terminal and the second terminal of each of the load circuit LC and the load circuit LCr can be changed.
Here, a method for changing the resistance between the first terminal and the second terminal of each of the load circuit LC and the load circuit LCr in the circuit MP in
For example, as the load circuit LC and the load circuit LCr, a variable resistor VR included in an ReRAM (Resistive Random Access Memory) or the like can be used, as illustrated in
As another example, as the load circuit LC and the load circuit LCr, a ferroelectric capacitor FEC that is sandwiched between a pair of electrodes and used in an FeRAM (Ferroelectric Random Access Memory) or the like can be used, as illustrated in
Note that in this case, the wiring VL functions not as a wiring for supplying a constant voltage but as a plate line for polarizing a ferroelectric film of the ferroelectric capacitor or inverting the polarization of the ferroelectric film.
To write the first data to the ferroelectric capacitor FEC, for example, writing is performed by turning on the transistor M8 to apply a voltage to the wiring IL and the wiring VL, thereby polarizing the ferroelectric film included in the ferroelectric capacitor FEC. To read the first data from the ferroelectric capacitor FEC, reading is performed by inputting a voltage corresponding to the second data to the wiring X1L and the wiring X2L to turn on or off the transistor M3 and the transistor M4 and then applying a pulse voltage to the wiring VL. In the ferroelectric capacitor FEC, whether the first data is “0” or “1” is determined depending on whether polarization inversion is caused by a pulse voltage from the wiring VL. When polarization inversion is caused in the ferroelectric film of the ferroelectric capacitor FEC, a current flows to the wiring OL through the transistor M3 or to the wiring OLB through the transistor M4. The amount of current flowing through the wiring OL and the wiring OLB can be obtained, for example, by using the circuit ACTF having a configuration of an integrator circuit (or a current-charge (IQ) converter circuit).
According to the above, with the use of the circuit MP in
The circuit MP according to one embodiment of the present invention including the load circuit LC and the load circuit LCr is not limited to having the configuration illustrated in
Note that this embodiment can be combined with any of the other embodiments in this specification as appropriate.
This embodiment describes structure examples of the semiconductor device described in the above embodiment and structure examples of transistors that can be used in the semiconductor device described in the above embodiment.
The transistor 500 is a transistor containing a metal oxide in a channel formation region (an OS transistor). The transistor 500 has features that the off-state current is low and that the field-effect mobility hardly changes even at high temperatures. The transistor 500 is used as a transistor included in a semiconductor device, for example, the arithmetic circuit 110, the arithmetic circuit 120, the arithmetic circuit 130, the arithmetic circuit 140, the arithmetic circuit 150, the arithmetic circuit 160, the arithmetic circuit 170, or the like described in the above embodiments, whereby a semiconductor device whose operating performance is less likely to degrade even at high temperatures can be obtained. In particular, when the transistor 500 is used as the transistor M2, the transistor M7, the transistor M8, and the transistor M9, for example, to utilize the feature of low off-state current, potentials written to the circuit HC, the circuit HCS, and the like can be held for a long time.
The transistor 500 is provided above the transistor 300, and the capacitor 600 is provided above the transistor 300 and the transistor 500, for example. Note that the capacitor 600 can be the capacitor included in the arithmetic circuit 110, the arithmetic circuit 120, the arithmetic circuit 130, the arithmetic circuit 140, the arithmetic circuit 150, the arithmetic circuit 160, the arithmetic circuit 170, and the like that are described in the above embodiments. Note that depending on a circuit configuration, the capacitor 600 illustrated in
The transistor 300 is provided on a substrate 310 and includes an element isolation layer 312, a conductor 316, an insulator 315, a semiconductor region 313 that is part of the substrate 310, and a low-resistance region 314a and a low-resistance region 314b functioning as a source region and a drain region. Note that the transistor 300 can be used as, for example, the transistor included in the arithmetic circuit 110, the arithmetic circuit 120, the arithmetic circuit 130, the arithmetic circuit 140, the arithmetic circuit 150, the arithmetic circuit 160, the arithmetic circuit 170, and the like described in the above embodiments. Specifically, the transistor 300 can be, for example, the transistor included in the comparator CMPa, the comparator CMPb, the operational amplifier OPa, and the operational amplifier OPb included in the circuits ACTF illustrated in
A semiconductor substrate (e.g., a single crystal substrate or a silicon substrate) is preferably used as the substrate 310.
As illustrated in
Note that the transistor 300 may be either a p-channel transistor or an n-channel transistor.
A region of the semiconductor region 313 where a channel is formed, a region in the vicinity thereof, the low-resistance region 314a and the low-resistance region 314b functioning as the source region and the drain region, and the like preferably contain a semiconductor such as a silicon-based semiconductor, further preferably contain single crystal silicon. Alternatively, the regions may be formed using a material containing Ge (germanium), SiGe (silicon germanium), GaAs (gallium arsenide), GaAlAs (gallium aluminum arsenide), GaN (gallium nitride), or the like. A structure may be employed in which silicon whose effective mass is controlled by applying stress to the crystal lattice and changing the lattice spacing is used. Alternatively, the transistor 300 may be an HEMT (High Electron Mobility Transistor) with GaAs and GaAlAs, or the like.
The low-resistance region 314a and the low-resistance region 314b contain an element that imparts n-type conductivity, such as arsenic or phosphorus, or an element that imparts p-type conductivity, such as boron, in addition to a semiconductor material used for the semiconductor region 313.
For the conductor 316 functioning as a gate electrode, a semiconductor material such as silicon containing an element that imparts n-type conductivity, such as arsenic or phosphorus, or an element that imparts p-type conductivity, such as boron, or a conductive material such as a metal material, an alloy material, or a metal oxide material can be used.
Note that since the work function of a conductor depends on the material of the conductor, the threshold voltage of the transistor can be adjusted by selecting the material of the conductor. Specifically, it is preferable to use a material such as titanium nitride or tantalum nitride for the conductor. Moreover, in order to ensure both conductivity and embeddability, it is preferable to use stacked layers of metal materials such as tungsten and aluminum for the conductor, and it is particularly preferable to use tungsten in terms of heat resistance.
The element isolation layer 312 is provided to separate a plurality of transistors on the substrate 310 from each other. The element isolation layer can be formed by, for example, a LOCOS (Local Oxidation of Silicon) method, an STI (Shallow Trench Isolation) method, a mesa isolation method, or the like.
Note that the transistor 300 illustrated in
Note that in
In the transistor 300 in
For the insulator 320, the insulator 322, the insulator 324, and the insulator 326, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, aluminum nitride oxide, or aluminum nitride can be used, for example.
Note that in this specification, silicon oxynitride refers to a material that has a higher oxygen content than a nitrogen content, and silicon nitride oxide refers to a material that has a higher nitrogen content than an oxygen content. Moreover, in this specification, aluminum oxynitride refers to a material that has a higher oxygen content than a nitrogen content, and aluminum nitride oxide refers to a material that has a higher nitrogen content than an oxygen content.
The insulator 322 may have a function of a planarization film for planarizing a level difference caused by the transistor 300 or the like covered with the insulator 320 and the insulator 322. For example, atop surface of the insulator 322 may be planarized by planarization treatment using a chemical mechanical polishing (CMP) method or the like to improve planarity.
As the insulator 324, it is preferable to use a film having a barrier property that prevents diffusion of hydrogen, impurities, or the like from the substrate 310, the transistor 300, or the like into a region where the transistor 500 is provided.
For the film having a barrier property against hydrogen, silicon nitride formed by a CVD method can be used, for example. Here, diffusion of hydrogen into a semiconductor element including an oxide semiconductor, such as the transistor 500, degrades the characteristics of the semiconductor element in some cases. Therefore, a film that inhibits hydrogen diffusion is preferably used between the transistor 500 and the transistor 300. The film that inhibits hydrogen diffusion is specifically a film from which a small amount of hydrogen is released.
The amount of released hydrogen can be analyzed by thermal desorption spectroscopy (TDS), for example. The amount of hydrogen released from the insulator 324 that is converted into hydrogen atoms per area of the insulator 324 is less than or equal to 10×1015 atoms/cm2, preferably less than or equal to 5×1015 atoms/cm2, in the TDS analysis in a film-surface temperature range of 50° C. to 500° C., for example.
Note that the permittivity of the insulator 326 is preferably lower than that of the insulator 324. For example, the dielectric constant of the insulator 326 is preferably lower than 4, further preferably lower than 3. The dielectric constant of the insulator 326 is, for example, preferably 0.7 times or less, further preferably 0.6 times or less the dielectric constant of the insulator 324. When a material with a low permittivity is used for the interlayer film, the parasitic capacitance generated between wirings can be reduced.
A conductor 328, a conductor 330, and the like that are connected to the capacitor 600 or the transistor 500 are embedded in the insulator 320, the insulator 322, the insulator 324, and the insulator 326. Note that the conductor 328 and the conductor 330 have a function of a plug or a wiring. A plurality of conductors having a function of a plug or a wiring are collectively denoted by the same reference numeral in some cases. Moreover, in this specification and the like, a wiring and a plug connected to the wiring may be a single component. That is, in some cases, part of a conductor functions as a wiring or part of a conductor functions as a plug.
As a material of each of plugs and wirings (e.g., the conductor 328 and the conductor 330), a single layer or stacked layers of a conductive material such as a metal material, an alloy material, a metal nitride material, or a metal oxide material can be used. It is preferable to use a high-melting-point material that has both heat resistance and conductivity, such as tungsten or molybdenum, and it is preferable to use tungsten. Alternatively, a low-resistance conductive material such as aluminum or copper is preferably used. The use of a low-resistance conductive material can reduce wiring resistance.
A wiring layer may be provided over the insulator 326 and the conductor 330. For example, in
For example, like the insulator 324, the insulator 350 is preferably formed using an insulator having a barrier property against impurities such as hydrogen and water. The insulator 352 and the insulator 354 are preferably formed using an insulator having a relatively low dielectric constant to reduce the parasitic capacitance generated between wirings, like the insulator 326. Furthermore, the conductor 356 preferably contains a conductor having a barrier property against impurities such as hydrogen and water. In particular, the conductor having a barrier property against hydrogen is formed in an opening portion included in the insulator 350 having a barrier property against hydrogen. With this structure, the transistor 300 and the transistor 500 can be separated by the barrier layer, so that diffusion of hydrogen from the transistor 300 into the transistor 500 can be inhibited.
For the conductor having a barrier property against hydrogen, tantalum nitride is preferably used, for example. In addition, the use of a stack including tantalum nitride and tungsten, which has high conductivity, can inhibit diffusion of hydrogen from the transistor 300 while the conductivity of a wiring is maintained. In that case, a structure is preferable in which a tantalum nitride layer having a barrier property against hydrogen is in contact with the insulator 350 having a barrier property against hydrogen.
An insulator 360, an insulator 362, and an insulator 364 are stacked in this order over the insulator 354 and the conductor 356.
Like the insulator 324 or the like, the insulator 360 is preferably formed using an insulator having a barrier property against impurities such as water and hydrogen. Thus, the insulator 360 can be formed using any of the materials usable for the insulator 324 or the like, for example.
The insulator 362 and the insulator 364 have functions of an interlayer insulating film and a planarization film. Like the insulator 324, the insulator 362 and the insulator 364 are preferably formed using an insulator having a barrier property against impurities such as water and hydrogen. Thus, the insulator 362 and/or the insulator 364 can be formed using any of the materials usable for the insulator 324.
An opening portion is provided in regions of the insulator 360, the insulator 362, and the insulator 364 that overlap with part of the conductor 356, and the conductor 366 is embedded to fill the opening portion. The conductor 366 is also formed over the insulator 362. The conductor 366 has a function of a plug or a wiring connected to the transistor 300, for example. Note that the conductor 366 can be provided using a material similar to those for the conductor 328 and the conductor 330.
An insulator 510, an insulator 512, an insulator 514, and an insulator 516 are stacked in this order over the insulator 364 and the conductor 366. A substance having a barrier property against oxygen, hydrogen, or the like is preferably used for any of the insulator 510, the insulator 512, the insulator 514, and the insulator 516.
For example, as the insulator 510 and the insulator 514, it is preferable to use a film having a barrier property that prevents diffusion of hydrogen, impurities, or the like from the substrate 310, a region where the transistor 300 is provided, or the like into the region where the transistor 500 is provided. Thus, a material similar to that for the insulator 324 can be used.
For the film having a barrier property against hydrogen, silicon nitride formed by a CVD method can be used, for example. Here, diffusion of hydrogen into a semiconductor element including an oxide semiconductor, such as the transistor 500, degrades the characteristics of the semiconductor element in some cases. Therefore, a film that inhibits hydrogen diffusion is preferably used between the transistor 500 and the transistor 300. The film that inhibits hydrogen diffusion is specifically a film from which a small amount of hydrogen is released.
For the film having a barrier property against hydrogen used for the insulator 510 and the insulator 514, a metal oxide such as aluminum oxide, hafnium oxide, or tantalum oxide is preferably used, for example.
In particular, aluminum oxide has an excellent blocking effect that prevents passage of oxygen and impurities such as hydrogen and moisture that would cause a change in the electrical characteristics of the transistor. Accordingly, aluminum oxide can prevent entry of impurities such as hydrogen and moisture into the transistor 500 in and after the manufacturing process of the transistor. In addition, release of oxygen from the oxide included in the transistor 500 can be inhibited. Therefore, aluminum oxide is suitably used for a protective film of the transistor 500.
For the insulator 512 and the insulator 516, a material similar to that for the insulator 320 can be used, for example. Furthermore, when a material with a comparatively low permittivity is used for these insulators, parasitic capacitance generated between wirings can be reduced. A silicon oxide film, a silicon oxynitride film, or the like can be used for the insulator 512 and the insulator 516, for example.
Furthermore, a conductor 518, a conductor included in the transistor 500 (e.g., a conductor 503 illustrated in
In particular, a region of the conductor 518 that is in contact with the insulator 510 and the insulator 514 is preferably a conductor having a barrier property against oxygen, hydrogen, and water. With this structure, the transistor 300 and the transistor 500 can be separated by the layer having a barrier property against oxygen, hydrogen, and water; hence, the diffusion of hydrogen from the transistor 300 into the transistor 500 can be inhibited.
The transistor 500 is provided above the insulator 516.
As illustrated in
An opening reaching the oxide 530b is provided in the insulator 580 and the insulator 544. The insulator 552, the insulator 550, the insulator 554, and the conductor 560 are positioned in the opening. The conductor 560, the insulator 552, the insulator 550, and the insulator 554 are provided between the conductor 542a and the conductor 542b and between the insulator 571a and the insulator 571b in the channel length direction of the transistor 500. The insulator 554 includes a region in contact with the side surface of the conductor 560 and a region in contact with the bottom surface of the conductor 560.
The oxide 530 preferably includes the oxide 530a placed over the insulator 524 and the oxide 530b placed over the oxide 530a. Including the oxide 530a under the oxide 530b makes it possible to inhibit diffusion of impurities into the oxide 530b from the components formed below the oxide 530a.
Although a structure in which two layers, the oxide 530a and the oxide 530b, are stacked as the oxide 530 in the transistor 500 is described, the present invention is not limited thereto. For example, the oxide 530 may be provided as a single layer of the oxide 530b or to have a stacked-layer structure of three or more layers, or the oxide 530a and the oxide 530b may each have a stacked-layer structure.
The conductor 560 functions as a first gate (also referred to as top gate) electrode, and the conductor 503 functions as a second gate (also referred to as back gate) electrode. The insulator 552, the insulator 550, and the insulator 554 function as a first gate insulator, and the insulator 522 and the insulator 524 function as a second gate insulator. Note that the gate insulator is also referred to as a gate insulating layer or a gate insulating film in some cases. The conductor 542a functions as one of a source and a drain, and the conductor 542b functions as the other of the source and the drain. At least part of a region of the oxide 530 that overlaps with the conductor 560 functions as a channel formation region.
Here,
The region 530bc functioning as the channel formation region has a smaller amount of oxygen vacancies (an oxygen vacancy in a metal oxide is sometimes referred to as V0 in this specification and the like) or a lower impurity concentration than the region 530ba and the region 530bb to be a high-resistance region having a low carrier concentration. Thus, the region 530bc can be regarded as being i-type (intrinsic) or substantially i-type.
A transistor using a metal oxide is likely to change its electrical characteristics when impurities or oxygen vacancies (VO) exist in a region of the metal oxide where a channel is formed, which might degrade the reliability. In some cases, hydrogen in the vicinity of an oxygen vacancy (VO) forms a defect that is an oxygen vacancy (VO) into which hydrogen enters (hereinafter sometimes referred to as VOH), which generates an electron serving as a carrier. Therefore, when the region of the oxide semiconductor where a channel is formed includes oxygen vacancies, the transistor tends to have normally-on characteristics (characteristics with which, even when no voltage is applied to the gate electrode, the channel exists and current flows through the transistor). Thus, impurities, oxygen vacancies, and VOH are preferably reduced as much as possible in the region of the oxide semiconductor where a channel is formed.
The region 530ba and the region 530bb functioning as the source region and the drain region are each a low-resistance region with an increased carrier concentration because they include a large amount of oxygen vacancies (VO) or have a high concentration of an impurity such as hydrogen, nitrogen, or a metal element. In other words, the region 530ba and the region 530bb are each an n-type region having a higher carrier concentration and a lower resistance than the region 530bc.
The carrier concentration in the region 530bc functioning as the channel formation region is preferably lower than or equal to 1×1018 cm−3, further preferably lower than 1×1017 cm−3, still further preferably lower than 1×1016 cm−3, yet further preferably lower than 1×1013 cm−3, yet still further preferably lower than 1×1012 cm−3. Note that the lower limit of the carrier concentration in the region 530bc functioning as the channel formation region is not particularly limited and can be, for example, 1×10−9 cm−3.
Between the region 530bc and the region 530ba or the region 530bb, a region having a carrier concentration that is lower than or substantially equal to the carrier concentrations in the region 530ba and the region 530bb and higher than or substantially equal to the carrier concentration in the region 530bc may be formed. That is, the region functions as a junction region between the region 530bc and the region 530ba or the region 530bb. The hydrogen concentration in the junction region is lower than or substantially equal to the hydrogen concentrations in the region 530ba and the region 530bb and higher than or substantially equal to the hydrogen concentration in the region 530bc in some cases. The amount of oxygen vacancies in the junction region is smaller than or substantially equal to the amounts of oxygen vacancies in the region 530ba and the region 530bb and larger than or substantially equal to the amount of oxygen vacancies in the region 530bc in some cases.
Although
In the oxide 530, the boundaries between the regions are difficult to detect clearly in some cases. The concentration of a metal element and an impurity element such as hydrogen or nitrogen, which is detected in each region, may be gradually changed not only between the regions but also in each region. That is, the region closer to the channel formation region preferably has a lower concentration of a metal element and an impurity element such as hydrogen or nitrogen.
In the transistor 500, a metal oxide functioning as a semiconductor (such a metal oxide is hereinafter also referred to as an oxide semiconductor) is preferably used for the oxide 530 (the oxide 530a and the oxide 530b) including the channel formation region.
The metal oxide functioning as a semiconductor preferably has a band gap of 2 eV or more, further preferably 2.5 eV or more. With the use of a metal oxide having such a wide band gap, the off-state current of the transistor can be reduced.
As the oxide 530, it is preferable to use, for example, a metal oxide such as an In-M-Zn oxide containing indium, an element M, and zinc (the element M is one or more kinds selected from aluminum, gallium, yttrium, tin, copper, vanadium, beryllium, boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, and the like). Alternatively, an In—Ga oxide, an In—Zn oxide, or an indium oxide may be used as the oxide 530.
Here, the atomic ratio of In to the element Min the metal oxide used as the oxide 530b is preferably greater than the atomic ratio of In to the element M in the metal oxide used as the oxide 530a.
The oxide 530a is provided under the oxide 530b in the above manner, whereby impurities and oxygen can be inhibited from diffusing into the oxide 530b from components formed below the oxide 530a.
When the oxide 530a and the oxide 530b contain a common element (as the main component) besides oxygen, the density of defect states at an interface between the oxide 530a and the oxide 530b can be made low. Since the density of defect states at the interface between the oxide 530a and the oxide 530b can be made low, the influence of interface scattering on carrier conduction is small, and a high on-state current can be obtained.
The oxide 530b preferably exhibits crystallinity. It is particularly preferable to use a CAAC-OS (c-axis aligned crystalline oxide semiconductor) as the oxide 530b.
The CAAC-OS is a metal oxide having a dense structure with high crystallinity and a small amount of impurities and defects (e.g., oxygen vacancies (VO)). In particular, after the formation of a metal oxide, heat treatment is performed at a temperature at which the metal oxide does not become a polycrystal (e.g., 400° C. to 600° C., inclusive), whereby a CAAC-OS having a dense structure with higher crystallinity can be obtained. When the density of the CAAC-OS is increased in such a manner, diffusion of impurities or oxygen in the CAAC-OS can be further reduced.
On the other hand, a clear crystal grain boundary is difficult to observe in the CAAC-OS; thus, it can be said that a reduction in electron mobility due to the crystal grain boundary is less likely to occur. Hence, a metal oxide including a CAAC-OS is physically stable. Therefore, the metal oxide including a CAAC-OS is resistant to heat and has high reliability.
If impurities and oxygen vacancies exist in a region of an oxide semiconductor where a channel is formed, a transistor using the oxide semiconductor might have variable electrical characteristics and poor reliability. In some cases, hydrogen in the vicinity of an oxygen vacancy forms a defect that is the oxygen vacancy into which hydrogen enters (VOH), which generates an electron serving as a carrier. Therefore, when the region of the oxide semiconductor where a channel is formed includes oxygen vacancies, the transistor tends to have normally-on characteristics (characteristics with which, even when no voltage is applied to the gate electrode, the channel exists and current flows through the transistor). Thus, impurities, oxygen vacancies, and VOH are preferably reduced as much as possible in the region of the oxide semiconductor where a channel is formed. In other words, it is preferable that the region of the oxide semiconductor where a channel is formed have a reduced carrier concentration and be of i-type (intrinsic) or substantially i-type.
As a countermeasure to the above, an insulator containing oxygen that is released by heating (hereinafter sometimes referred to as excess oxygen) is provided in the vicinity of the oxide semiconductor and heat treatment is performed, so that oxygen can be supplied from the insulator to the oxide semiconductor to reduce oxygen vacancies and VOH. However, supply of an excess amount of oxygen to the source region or the drain region might cause a decrease in the on-state current or field-effect mobility of the transistor 500. Furthermore, a variation of oxygen supplied to the source region or the drain region in the substrate plane leads to a variation in characteristics of the semiconductor device including the transistor.
Therefore, the region 530bc functioning as the channel formation region in the oxide semiconductor is preferably an i-type or substantially i-type region with a reduced carrier concentration, whereas the region 530ba and the region 530bb functioning as the source region and the drain region are preferably n-type regions with high carrier concentrations. That is, it is preferable that oxygen vacancies and VOH in the region 530bc of the oxide semiconductor be reduced and the region 530ba and the region 530bb not be supplied with an excess amount of oxygen.
Thus, in this embodiment, microwave treatment is performed in an oxygen-containing atmosphere in a state where the conductor 542a and the conductor 542b are provided over the oxide 530b so that oxygen vacancies and VOH in the region 530bc can be reduced. Here, the microwave treatment refers to, for example, treatment using an apparatus including a power source that generates high-density plasma with the use of a microwave.
The microwave treatment in an oxygen-containing atmosphere converts an oxygen gas into plasma using a high-frequency wave such as a microwave or RF and activates the oxygen plasma. At this time, the region 530bc can be irradiated with the high-frequency wave such as a microwave or RF. By the effect of the plasma, a microwave, or the like, VOH in the region 530bc can be cut; thus, hydrogen H can be removed from the region 530bc and an oxygen vacancy VO can be filled with oxygen. That is, the reaction “VOH→H+VO” occurs in the region 530bc, so that the hydrogen concentration in the region 530bc can be reduced. As a result, oxygen vacancies and VOH in the region 530bc can be reduced to lower the carrier concentration.
In the microwave treatment in an oxygen-containing atmosphere, the high-frequency wave such as the microwave or RF, the oxygen plasma, or the like is blocked by the conductor 542a and the conductor 542b and does not affect the region 530ba nor the region 530bb. In addition, the effect of the oxygen plasma can be reduced by the insulator 571 and the insulator 580 that are provided to cover the oxide 530b and the conductor 542. Hence, a reduction in VOH and supply of an excess amount of oxygen do not occur in the region 530ba and the region 530bb in the microwave treatment, preventing a decrease in carrier concentration.
Microwave treatment is preferably performed in an oxygen-containing atmosphere after formation of an insulating film to be the insulator 552 or after formation of an insulating film to be the insulator 550. By performing the microwave treatment in an oxygen-containing atmosphere through the insulator 552 or the insulator 550 in such a manner, oxygen can be efficiently supplied into the region 530bc. In addition, the insulator 552 is provided to be in contact with the side surface of the conductor 542 and the surface of the region 530bc, thereby preventing oxygen more than necessary from being supplied to the region 530bc and preventing the side surface of the conductor 542 from being oxidized. Furthermore, the side surface of the conductor 542 can be inhibited from being oxidized when an insulating film to be the insulator 550 is formed.
The oxygen supplied into the region 530bc has any of a variety of forms such as an oxygen atom, an oxygen molecule, and an oxygen radical (also referred to as O radical which is an atom, a molecule, or an ion having an unpaired electron). Note that the oxygen supplied into the region 530bc preferably has any one or more of the above forms, and is particularly preferably an oxygen radical. In such a case, the film quality of the insulator 552 and the insulator 550 can be improved, leading to higher reliability of the transistor 500.
In the above manner, oxygen vacancies and VOH can be selectively removed from the region 530bc in the oxide semiconductor, whereby the region 530bc can be an i-type or substantially i-type region. Furthermore, supply of an excess amount of oxygen to the region 530ba and the region 530bb functioning as the source region and the drain region can be inhibited, and the n-type conductivity can be maintained. As a result, a change in the electrical characteristics of the transistor 500 can be inhibited, and thus a variation in the electrical characteristics of the transistors 500 in the substrate plane can be reduced.
With the above structure, a semiconductor device with a small variation in transistor characteristics can be provided. A semiconductor device with favorable reliability can be provided. A semiconductor device having favorable electrical characteristics can be provided.
As illustrated in
The radius of curvature of the curved surface is preferably greater than 0 nm and less than the thickness of the oxide 530b in a region overlapping with the conductor 542, or less than half of the length of a region that does not have the curved surface. Specifically, the radius of curvature of the curved surface is greater than 0 nm and less than or equal to 20 nm, preferably greater than or equal to 1 nm and less than or equal to 15 nm, further preferably greater than or equal to 2 nm and less than or equal to 10 nm. Such a shape can improve the coverage of the oxide 530b with the insulator 552, the insulator 550, the insulator 554, and the conductor 560.
The oxide 530 preferably has a stacked-layer structure of a plurality of oxide layers with different chemical compositions. Specifically, the atomic ratio of the element M to a metal element that is a main component of the metal oxide used as the oxide 530a is preferably higher than the atomic ratio of the element M to a metal element that is a main component of the metal oxide used as the oxide 530b. In addition, the atomic ratio of the element M to In in the metal oxide used as the oxide 530a is preferably higher than the atomic ratio of the element M to In in the metal oxide used as the oxide 530b. Furthermore, the atomic ratio of In to the element Min the metal oxide used as the oxide 530b is preferably higher than the atomic ratio of In to the element Min the metal oxide used as the oxide 530a.
The oxide 530b is preferably an oxide having crystallinity, such as a CAAC-OS. An oxide having crystallinity, such as a CAAC-OS, has a dense structure with small amounts of impurities and defects (e.g., oxygen vacancies) and high crystallinity. This can inhibit extraction of oxygen from the oxide 530b by the source electrode or the drain electrode. This can reduce extraction of oxygen from the oxide 530b even when heat treatment is performed; hence, the transistor 500 is stable against high temperatures in the manufacturing process (what is called thermal budget).
Here, the conduction band minimum gradually changes at a junction portion of the oxide 530a and the oxide 530b. In other words, the conduction band minimum at the junction portion of the oxide 530a and the oxide 530b continuously changes or is continuously connected. To achieve this, the density of defect states in a mixed layer formed at the interface between the oxide 530a and the oxide 530b is preferably made low.
Specifically, when the oxide 530a and the oxide 530b include the same element as a main component in addition to oxygen, a mixed layer with a low density of defect states can be formed. For example, in the case where the oxide 530b is an In-M-Zn oxide, an In-M-Zn oxide, an M-Zn oxide, an oxide of the element M, an In—Zn oxide, indium oxide, or the like may be used as the oxide 530a.
Specifically, as the oxide 530a, a metal oxide with a composition of In:M:Zn=1:3:4 [atomic ratio] or in the neighborhood thereof, or a composition of In:M:Zn=1:1:0.5 [atomic ratio] or in the neighborhood thereof is used. As the oxide 530b, a metal oxide with a composition of In:M:Zn=1:1:1 [atomic ratio] or in the neighborhood thereof, or a composition of In:M:Zn=4:2:3 [atomic ratio] or in the neighborhood thereof is used. Note that a composition in the neighborhood includes the range of ±30% of an intended atomic ratio. Gallium is preferably used as the element M.
When the metal oxide is deposited by a sputtering method, the above atomic ratio is not limited to the atomic ratio of the deposited metal oxide and may be the atomic ratio of a sputtering target used for depositing the metal oxide.
As illustrated in
When the oxide 530a and the oxide 530b have the above structure, the density of defect states at the interface between the oxide 530a and the oxide 530b can be made low. Thus, the influence of interface scattering on carrier conduction is small, and the transistor 500 can have a high on-state current and excellent frequency characteristics.
At least one of the insulator 512, the insulator 514, the insulator 544, the insulator 571, the insulator 574, an insulator 576, and an insulator 581 preferably functions as a barrier insulating film, which inhibits diffusion of impurities such as water and hydrogen from the substrate side or above the transistor 500 into the transistor 500. Thus, for at least one of the insulator 512, the insulator 514, the insulator 544, the insulator 571, the insulator 574, the insulator 576, and the insulator 581, it is preferable to use an insulating material having a function of inhibiting diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (e.g., N2O, NO, or NO2), or copper atoms (an insulating material through which the impurities are less likely to pass). Alternatively, it is preferable to use an insulating material having a function of inhibiting diffusion of oxygen (e.g., at least one of oxygen atoms, oxygen molecules, and the like) (an insulating material through which the oxygen is less likely to pass).
Note that in this specification, a barrier insulating film refers to an insulating film having a barrier property. A barrier property in this specification means a function of inhibiting diffusion of a targeted substance (also referred to as a function of less easily transmitting the substance). In addition, a barrier property in this specification means a function of capturing and fixing (also referred to as gettering) a targeted substance.
An insulator having a function of inhibiting diffusion of oxygen and impurities such as water and hydrogen is preferably used as the insulator 512, the insulator 514, the insulator 544, the insulator 571, the insulator 574, the insulator 576, and the insulator 581; for example, aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon nitride, or silicon nitride oxide can be used. For example, silicon nitride, which has a higher hydrogen barrier property, is preferably used for the insulator 512, the insulator 544, and the insulator 576. For example, aluminum oxide or magnesium oxide, which has a function of capturing or fixing hydrogen well, is preferably used for the insulator 514, the insulator 571, the insulator 574, and the insulator 581. In such a case, impurities such as water and hydrogen can be inhibited from diffusing to the transistor 500 side from the substrate side through the insulator 512 and the insulator 514. Alternatively, impurities such as water and hydrogen can be inhibited from diffusing to the transistor 500 side from an interlayer insulating film and the like that are positioned on the outer side compared to the insulator 581. Alternatively, oxygen contained in the insulator 524 and the like can be inhibited from diffusing to the substrate side through the insulator 512 and the insulator 514. Alternatively, oxygen contained in the insulator 580 and the like can be inhibited from diffusing to above the transistor 500 through the insulator 574 and the like. In this manner, it is preferable that the transistor 500 be surrounded by the insulator 512, the insulator 514, the insulator 571, the insulator 544, the insulator 574, the insulator 576, and the insulator 581, which have a function of inhibiting diffusion of oxygen and impurities such as water and hydrogen.
Here, an oxide having an amorphous structure is preferably used for the insulator 512, the insulator 514, the insulator 544, the insulator 571, the insulator 574, the insulator 576, and the insulator 581. For example, a metal oxide such as AlOx (x is a given number greater than 0) or MgOy (y is a given number greater than 0) is preferably used. In such a metal oxide having an amorphous structure, an oxygen atom has a dangling bond and sometimes has a property of capturing or fixing hydrogen with the dangling bond. When such a metal oxide having an amorphous structure is used as the component of the transistor 500 or provided around the transistor 500, hydrogen contained in the transistor 500 or hydrogen present around the transistor 500 can be captured or fixed. In particular, hydrogen contained in the channel formation region of the transistor 500 is preferably captured or fixed. The metal oxide having an amorphous structure is used as the component of the transistor 500 or provided around the transistor 500, whereby the transistor 500 and a semiconductor device that have favorable characteristics and high reliability can be manufactured.
Although each of the insulator 512, the insulator 514, the insulator 544, the insulator 571, the insulator 574, the insulator 576, and the insulator 581 preferably has an amorphous structure, a region having a polycrystalline structure may be partly formed. Alternatively, each of the insulator 512, the insulator 514, the insulator 544, the insulator 571, the insulator 574, the insulator 576, and the insulator 581 may have a multilayer structure in which a layer having an amorphous structure and a layer having a polycrystalline structure are stacked. For example, a stacked-layer structure in which a layer having a polycrystalline structure is formed over a layer having an amorphous structure may be employed.
The insulator 512, the insulator 514, the insulator 544, the insulator 571, the insulator 574, the insulator 576, and the insulator 581 can be deposited by a sputtering method, for example. Since a sputtering method does not need to use a molecule containing hydrogen as a deposition gas, the hydrogen concentrations in the insulator 512, the insulator 514, the insulator 544, the insulator 571, the insulator 574, the insulator 576, and the insulator 581 can be reduced. Note that the deposition method is not limited to a sputtering method, and a chemical vapor deposition (CVD) method, a molecular beam epitaxy (MBE) method, a pulsed laser deposition (PLD) method, an atomic layer deposition (ALD) method, or the like may be used as appropriate.
The resistivities of the insulator 512, the insulator 544, and the insulator 576 are preferably low in some cases. For example, by setting the resistivities of the insulator 512, the insulator 544, and the insulator 576 to approximately 1×1013 Ωcm, the insulator 512, the insulator 544, and the insulator 576 can sometimes reduce charge up of the conductor 503, the conductor 542, the conductor 560, or the like in treatment using plasma or the like in the manufacturing process of a semiconductor device. The resistivities of the insulator 512, the insulator 544, and the insulator 576 are preferably higher than or equal to 1×1010 Ωcm and lower than or equal to 1×1015 Ωcm.
The insulator 516, the insulator 574, the insulator 580, and the insulator 581 each preferably have a lower permittivity than the insulator 514. When a material with a low permittivity is used for an interlayer film, parasitic capacitance generated between wirings can be reduced. For the insulator 516, the insulator 580, and the insulator 581, silicon oxide, silicon oxynitride, silicon oxide to which fluorine is added, silicon oxide to which carbon is added, silicon oxide to which carbon and nitrogen are added, porous silicon oxide, or the like is used as appropriate, for example.
The insulator 581 is preferably an insulator functioning as an interlayer film, a planarization film, or the like, for example.
The conductor 503 is positioned to overlap with the oxide 530 and the conductor 560. Here, the conductor 503 is preferably provided to be embedded in an opening formed in the insulator 516. Part of the conductor 503 is embedded in the insulator 514 in some cases.
The conductor 503 includes the conductor 503a and the conductor 503b. The conductor 503a is provided in contact with a bottom surface and a sidewall of the opening. The conductor 503b is provided to be embedded in a recessed portion formed in the conductor 503a. Here, the upper portion of the conductor 503b is substantially level with the upper portion of the conductor 503a and the upper portion of the insulator 516.
Here, for the conductor 503a, it is preferable to use a conductive material having a function of inhibiting diffusion of impurities such as a hydrogen atom, a hydrogen molecule, a water molecule, a nitrogen atom, a nitrogen molecule, a nitrogen oxide molecule (N2O, NO, NO2, or the like), and a copper atom. Alternatively, it is preferable to use a conductive material that has a function of inhibiting the diffusion of oxygen (e.g., at least one of an oxygen atom, an oxygen molecule, and the like).
When the conductor 503a is formed using a conductive material having a function of inhibiting diffusion of hydrogen, impurities such as hydrogen contained in the conductor 503b can be prevented from diffusing into the oxide 530 through the insulator 524 and the like. When the conductor 503a is formed using a conductive material having a function of inhibiting diffusion of oxygen, the conductivity of the conductor 503b can be inhibited from being lowered because of oxidation. As the conductive material having a function of inhibiting diffusion of oxygen, for example, titanium, titanium nitride, tantalum, tantalum nitride, ruthenium, or ruthenium oxide is preferably used. Thus, the conductor 503a is a single layer or stacked layers of the above conductive materials. For example, tungsten is used for the conductor 503a.
Moreover, the conductor 503b is preferably formed using a conductive material containing tungsten, copper, or aluminum as its main component. For example, tungsten is used for the conductor 503b.
The conductor 503 sometimes functions as a second gate electrode. In that case, by changing a potential applied to the conductor 503 not in conjunction with but independently of a potential applied to the conductor 560, the threshold voltage (Vth) of the transistor 500 can be controlled. In particular, Vth of the transistor 500 can be higher in the case where a negative potential is applied to the conductor 503, and the off-state current can be reduced. Thus, a drain current at the time when a potential applied to the conductor 560 is 0 V can be lower in the case where a negative potential is applied to the conductor 503 than in the case where the negative potential is not applied to the conductor 503.
The electric resistivity of the conductor 503 is designed in consideration of the potential applied to the conductor 503, and the thickness of the conductor 503 is determined in accordance with the electric resistivity. The thickness of the insulator 516 is substantially equal to that of the conductor 503. The conductor 503 and the insulator 516 are preferably as thin as possible in the allowable range of the design of the conductor 503. When the thickness of the insulator 516 is reduced, the absolute amount of impurities such as hydrogen contained in the insulator 516 can be reduced, reducing the amount of the impurities to be diffused into the oxide 530.
When seen from above, the conductor 503 is preferably provided to be larger than a region of the oxide 530 that does not overlap with the conductor 542a or the conductor 542b. As illustrated in
In this specification and the like, a transistor having the S-channel structure refers to a transistor having a structure in which a channel formation region is electrically surrounded by the electric fields of a pair of gate electrodes. The S-channel structure disclosed in this specification and the like is different from a Fin-type structure and a planar structure. With the S-channel structure, resistance to a short-channel effect can be enhanced, that is, a transistor in which a short-channel effect is less likely to occur can be provided.
As illustrated in
Although the transistor 500 having a structure in which the conductor 503 is a stack of the conductor 503a and the conductor 503b is illustrated, the present invention is not limited thereto. For example, the conductor 503 may be provided as a single layer or to have a stacked-layer structure of three or more layers.
The insulator 522 and the insulator 524 function as a gate insulator.
It is preferable that the insulator 522 have a function of inhibiting diffusion of hydrogen (e.g., at least one of a hydrogen atom, a hydrogen molecule, and the like). In addition, it is preferable that the insulator 522 have a function of inhibiting diffusion of oxygen (e.g., at least one of an oxygen atom, an oxygen molecule, and the like). For example, the insulator 522 preferably has a function of inhibiting diffusion of one or both of hydrogen and oxygen more than the insulator 524.
As the insulator 522, an insulator containing an oxide of one or both of aluminum and hafnium, which is an insulating material, is preferably used. For the insulator, aluminum oxide, hafnium oxide, an oxide containing aluminum and hafnium (hafnium aluminate), or the like is preferably used. In the case where the insulator 522 is formed using such a material, the insulator 522 functions as a layer that inhibits release of oxygen from the oxide 530 to the substrate side and diffusion of impurities such as hydrogen from the periphery of the transistor 500 into the oxide 530. Thus, providing the insulator 522 can inhibit diffusion of impurities such as hydrogen into the transistor 500 and inhibit generation of oxygen vacancies in the oxide 530. Moreover, the conductor 503 can be inhibited from reacting with oxygen contained in at least one of the insulator 524 and the oxide 530.
Alternatively, aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, or zirconium oxide may be added to the above insulator, for example. Alternatively, the insulator may be subjected to nitriding treatment. A stack of silicon oxide, silicon oxynitride, or silicon nitride over these insulators may be used for the insulator 522.
For example, a single layer or stacked layers of an insulator containing what is called a high-k material such as aluminum oxide, hafnium oxide, tantalum oxide, or zirconium oxide may be used for the insulator 522. As miniaturization and high integration of transistors progress, a problem such as leakage current may arise because of a thinner gate insulator. When a high-k material is used for an insulator functioning as the gate insulator, a gate potential at the time when the transistor operates can be lowered while the physical thickness is maintained. In some cases, a substance with a high permittivity, such as lead zirconate titanate (PZT), strontium titanate (SrTiO3), or (Ba,Sr)TiO3 (BST), can be used for the insulator 522.
Silicon oxide or silicon oxynitride, for example, can be used as appropriate for the insulator 524 that is in contact with the oxide 530.
In a manufacturing process of the transistor 500, heat treatment is preferably performed with the surface of the oxide 530 exposed. For example, the heat treatment is performed at a temperature higher than or equal to 100° C. and lower than or equal to 600° C., preferably higher than or equal to 350° C. and lower than or equal to 550° C. Note that the heat treatment is performed in a nitrogen gas or inert gas atmosphere, or an atmosphere containing an oxidizing gas at 10 ppm or more, 1% or more, or 10% or more. For example, the heat treatment is preferably performed in an oxygen atmosphere. Accordingly, oxygen can be supplied to the oxide 530 to reduce oxygen vacancies (VO). The heat treatment may be performed under reduced pressure. Alternatively, the heat treatment may be performed in such a manner that heat treatment is performed in a nitrogen gas or inert gas atmosphere, and then another heat treatment is performed in an atmosphere containing an oxidizing gas at 10 ppm or more, 1% or more, or 10% or more in order to compensate for released oxygen. Alternatively, the heat treatment may be performed in such a manner that heat treatment is performed in an atmosphere containing an oxidizing gas at 10 ppm or more, 1% or more, or 10% or more, and then another heat treatment is successively performed in a nitrogen gas or inert gas atmosphere.
Note that the oxygen adding treatment performed on the oxide 530 can promote a reaction in which oxygen vacancies in the oxide 530 are filled with supplied oxygen, i.e., a reaction of “VO+O→null”. Furthermore, hydrogen remaining in the oxide 530 reacts with supplied oxygen, so that the hydrogen can be removed as H2O (dehydration). This can inhibit recombination of hydrogen remaining in the oxide 530 with oxygen vacancies and formation of VOH.
Note that the insulator 522 and the insulator 524 may each have a stacked-layer structure of two or more layers. In that case, without limitation to a stacked-layer structure formed of the same material, a stacked-layer structure formed of different materials may be employed. The insulator 524 may be formed into an island shape so as to overlap with the oxide 530a. In this case, the insulator 544 is in contact with the side surface of the insulator 524 and the top surface of the insulator 522.
The conductor 542a and the conductor 542b are provided in contact with the top surface of the oxide 530b. The conductor 542a and the conductor 542b function as a source electrode and a drain electrode of the transistor 500.
For the conductor 542 (the conductor 542a and the conductor 542b), for example, a nitride containing tantalum, a nitride containing titanium, a nitride containing molybdenum, a nitride containing tungsten, a nitride containing tantalum and aluminum, a nitride containing titanium and aluminum, or the like is preferably used. In one embodiment of the present invention, a nitride containing tantalum is particularly preferable. As another example, ruthenium oxide, ruthenium nitride, an oxide containing strontium and ruthenium, or an oxide containing lanthanum and nickel may be used. These materials are preferable because they are each a conductive material that is not easily oxidized or a material that maintains the conductivity even after absorbing oxygen.
Note that hydrogen contained in the oxide 530b or the like diffuses into the conductor 542a or the conductor 542b in some cases. In particular, when a nitride containing tantalum is used for the conductor 542a and the conductor 542b, hydrogen contained in the oxide 530b or the like is likely to diffuse into the conductor 542a or the conductor 542b, and the diffused hydrogen is bonded to nitrogen contained in the conductor 542a or the conductor 542b in some cases. That is, hydrogen contained in the oxide 530b or the like is absorbed by the conductor 542a or the conductor 542b in some cases.
No curved surface is preferably formed between the side surface of the conductor 542 and the top surface of the conductor 542. When no curved surface is formed in the conductor 542, the conductor 542 can have a large cross-sectional area in the channel width direction. Accordingly, the conductivity of the conductor 542 is increased, so that the on-state current of the transistor 500 can be increased.
The insulator 571a is provided in contact with the top surface of the conductor 542a, and the insulator 571b is provided in contact with the top surface of the conductor 542b. The insulator 571 preferably functions as at least a barrier insulating film against oxygen. Thus, the insulator 571 preferably has a function of inhibiting oxygen diffusion. For example, the insulator 571 preferably has a function of inhibiting diffusion of oxygen more than the insulator 580. For example, a nitride containing silicon, such as silicon nitride, may be used for the insulator 571. The insulator 571 preferably has a function of capturing impurities such as hydrogen. In that case, for the insulator 571, a metal oxide having an amorphous structure, for example, an insulator such as aluminum oxide or magnesium oxide, may be used. It is particularly preferable to use aluminum oxide having an amorphous structure for the insulator 571 because hydrogen can be captured or fixed more effectively in some cases. Accordingly, the transistor 500 and a semiconductor device that have favorable characteristics and high reliability can be manufactured.
The insulator 544 is provided to cover the insulator 524, the oxide 530a, the oxide 530b, the conductor 542, and the insulator 571. The insulator 544 preferably has a function of capturing and fixing hydrogen. In that case, the insulator 544 preferably includes silicon nitride, or a metal oxide having an amorphous structure, for example, an insulator such as aluminum oxide or magnesium oxide. Alternatively, for example, a stacked-layer film of aluminum oxide and silicon nitride over the aluminum oxide may be used as the insulator 544.
When the above insulator 571 and insulator 544 are provided, the conductor 542 can be surrounded by the insulators having a barrier property against oxygen. That is, oxygen contained in the insulator 524 and the insulator 580 can be prevented from diffusing into the conductor 542. As a result, the conductor 542 can be inhibited from being directly oxidized by oxygen contained in the insulator 524 and the insulator 580, so that an increase in resistivity and a reduction in on-state current can be inhibited.
The insulator 552 functions as part of a gate insulator. As the insulator 552, a barrier insulating film against oxygen is preferably used. As the insulator 552, an insulator that can be used as the insulator 574 described above may be used. An insulator containing an oxide of one or both of aluminum and hafnium is preferably used as the insulator 552. As the insulator, aluminum oxide, hafnium oxide, an oxide containing aluminum and hafnium (hafnium aluminate), an oxide containing hafnium and silicon (hafnium silicate), or the like can be used. In this embodiment, aluminum oxide is used for the insulator 552. In this case, the insulator 552 is an insulator containing at least oxygen and aluminum.
As illustrated in
Even when an excess amount of oxygen is contained in the insulator 580, the insulator 550, and the like, oxygen can be inhibited from being excessively supplied to the oxide 530a and the oxide 530b. Thus, the region 530ba and the region 530bb are prevented from being excessively oxidized by oxygen through the region 530bc; a reduction in on-state current or field-effect mobility of the transistor 500 can be inhibited.
As illustrated in
Furthermore, the insulator 552 needs to be provided in an opening formed in the insulator 580 and the like, together with the insulator 554, the insulator 550, and the conductor 560. The thickness of the insulator 552 is preferably small for miniaturization of the transistor 500. The thickness of the insulator 552 is preferably greater than or equal to 0.1 nm, greater than or equal to 0.5 nm, or greater than or equal to 1.0 nm, and less than or equal to 1.0 nm, less than or equal to 3.0 nm, or less than or equal to 5.0 nm. Note that any of the above-described lower limits and upper limits can be combined with each other. In that case, at least part of the insulator 552 includes a region having the above-described thickness. The thickness of the insulator 552 is preferably smaller than that of the insulator 550. In that case, at least part of the insulator 552 includes a region having a thickness smaller than that of the insulator 550.
To form the insulator 552 having a small thickness like the above-described thickness, an ALD method is preferably used for deposition. Examples of an ALD method include a thermal ALD method, in which a precursor and a reactant react with each other only by a thermal energy, and a PEALD (Plasma Enhanced ALD) method, in which a reactant excited by plasma is used. The use of plasma in a PEALD method is sometimes preferable because deposition at a lower temperature is possible.
An ALD method, which enables an atomic layer to be deposited one by one using self-limiting characteristics by atoms, has advantages such as deposition of an extremely thin film, deposition on a component with a high aspect ratio, deposition of a film with a small number of defects such as pinholes, deposition with excellent coverage, and low-temperature deposition. Therefore, the insulator 552 can be formed on the side surface of the opening formed in the insulator 580 and the like to have a small thickness as described above and to have favorable coverage.
Note that some of precursors usable in an ALD method contain carbon or the like. Thus, in some cases, a film provided by an ALD method contains impurities such as carbon in a larger amount than a film provided by another deposition method. Note that impurities can be quantified by secondary ion mass spectrometry (SIMS) or X-ray photoelectron spectroscopy (XPS).
The insulator 550 functions as part of the gate insulator. The insulator 550 is preferably provided in contact with the top surface of the insulator 552. The insulator 550 can be formed using silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, silicon oxide to which fluorine is added, silicon oxide to which carbon is added, silicon oxide to which carbon and nitrogen are added, porous silicon oxide, or the like. In particular, silicon oxide and silicon oxynitride, which have thermal stability, are preferable. The insulator 550 in this case is an insulator containing at least oxygen and silicon.
As in the insulator 524, the concentration of impurities such as water and hydrogen in the insulator 550 is preferably reduced. The thickness of the insulator 550 is preferably greater than or equal to 1 nm or greater than or equal to 0.5 nm and less than or equal to 15.0 nm or less than or equal to 20 nm. Note that any of the above-described lower limits and upper limits can be combined with each other. In that case, at least part of the insulator 550 includes a region having the above-described thickness.
Although
In the case where the insulator 550 has a stacked-layer structure of two layers as illustrated in
In the case where silicon oxide, silicon oxynitride, or the like is used for the insulator 550a, the insulator 550b may be formed using an insulating material that is a high-k material having a high dielectric constant. The gate insulator having a stacked-layer structure of the insulator 550a and the insulator 550b can be thermally stable and can have a high dielectric constant. Thus, a gate potential that is applied during the operation of the transistor can be lowered while the physical thickness of the gate insulator is maintained. In addition, the equivalent oxide thickness (EOT) of the insulator functioning as the gate insulator can be reduced. Therefore, the withstand voltage of the insulator 550 can be increased.
The insulator 554 functions as part of the gate insulator. As the insulator 554, a barrier insulating film against hydrogen is preferably used. This can prevent diffusion of impurities such as hydrogen contained in the conductor 560 into the insulator 550 and the oxide 530b. As the insulator 554, an insulator that can be used as the insulator 576 described above may be used. For example, silicon nitride deposited by a PEALD method may be used as the insulator 554. In this case, the insulator 554 is an insulator containing at least nitrogen and silicon.
The insulator 554 may have a barrier property against oxygen. Thus, diffusion of oxygen contained in the insulator 550 into the conductor 560 can be inhibited.
The insulator 554 needs to be provided in an opening formed in the insulator 580 and the like, together with the insulator 552, the insulator 550, and the conductor 560. The thickness of the insulator 554 is preferably small for miniaturization of the transistor 500. The thickness of the insulator 554 is preferably greater than or equal to 0.1 nm, greater than or equal to 0.5 nm, or greater than or equal to 1.0 nm, and less than or equal to 3.0 nm or less than or equal to 5.0 nm. Note that any of the above-described lower limits and upper limits can be combined with each other. In that case, at least part of the insulator 554 includes a region having the above-described thickness. The thickness of the insulator 554 is preferably smaller than that of the insulator 550. In that case, at least part of the insulator 554 includes a region having a thickness smaller than that of the insulator 550.
The conductor 560 functions as the first gate electrode of the transistor 500. The conductor 560 preferably includes the conductor 560a and the conductor 560b provided over the conductor 560a. For example, the conductor 560a is preferably provided to cover the bottom surface and the side surface of the conductor 560b. As illustrated in
For the conductor 560a, it is preferable to use a conductive material that has a function of inhibiting diffusion of impurities such as a hydrogen atom, a hydrogen molecule, a water molecule, a nitrogen atom, a nitrogen molecule, a nitrogen oxide molecule, and a copper atom. Alternatively, it is preferable to use a conductive material that has a function of inhibiting diffusion of oxygen (e.g., at least one of an oxygen atom, an oxygen molecule, and the like).
When the conductor 560a has a function of inhibiting diffusion of oxygen, it is possible to inhibit a reduction in conductivity of the conductor 560b due to oxidation caused by oxygen contained in the insulator 550. As the conductive material having a function of inhibiting diffusion of oxygen, for example, titanium, titanium nitride, tantalum, tantalum nitride, ruthenium, or ruthenium oxide is preferably used.
Furthermore, the conductor 560 also functions as a wiring and thus a conductor having high conductivity is preferably used for the conductor 560. For example, a conductive material containing tungsten, copper, or aluminum as its main component can be used for the conductor 560b. Moreover, the conductor 560b may have a stacked-layer structure, for example, a stacked-layer structure of titanium or titanium nitride and the above conductive material.
In the transistor 500, the conductor 560 is formed in a self-aligned manner to fill the opening formed in the insulator 580 and the like. The formation of the conductor 560 in this manner allows the conductor 560 to be placed properly in a region between the conductor 542a and the conductor 542b without alignment.
As illustrated in
The insulator 580 is provided over the insulator 544, and the opening is formed in a region where the insulator 550 and the conductor 560 are to be provided. In addition, the top surface of the insulator 580 may be planarized.
The insulator 580 functioning as an interlayer film preferably has a low permittivity. When a material with a low permittivity is used for an interlayer film, parasitic capacitance generated between wirings can be reduced. The insulator 580 is preferably provided using a material similar to that for the insulator 516, for example. In particular, silicon oxide and silicon oxynitride, which have thermal stability, are preferable. Materials such as silicon oxide, silicon oxynitride, and porous silicon oxide are particularly preferable because a region containing oxygen to be released by heating can be easily formed.
The concentration of impurities such as water and hydrogen in the insulator 580 is preferably reduced. An oxide containing silicon, such as silicon oxide or silicon oxynitride, is used as appropriate for the insulator 580, for example.
The insulator 574 preferably functions as a barrier insulating film that inhibits impurities such as water and hydrogen from diffusing into the insulator 580 from above and preferably has a function of capturing impurities such as hydrogen. The insulator 574 preferably functions as a barrier insulating film that inhibits passage of oxygen. For the insulator 574, a metal oxide having an amorphous structure, for example, an insulator such as aluminum oxide, can be used. In this case, the insulator 574 is an insulator containing at least oxygen and aluminum. The insulator 574, which has a function of capturing impurities such as hydrogen, is provided in contact with the insulator 580 in a region sandwiched between the insulator 512 and the insulator 581, whereby impurities such as hydrogen contained in the insulator 580 and the like can be captured and the amount of hydrogen in the region can be constant. It is particularly preferable to use aluminum oxide having an amorphous structure for the insulator 574, in which case hydrogen can sometimes be captured or fixed more effectively. Accordingly, the transistor 500 and a semiconductor device that have favorable characteristics and high reliability can be manufactured.
The insulator 576 functions as a barrier insulating film that inhibits impurities such as water and hydrogen from diffusing into the insulator 580 from above. The insulator 576 is provided over the insulator 574. The insulator 576 is preferably formed using a nitride containing silicon, such as silicon nitride or silicon nitride oxide. For example, silicon nitride deposited by a sputtering method may be used for the insulator 576. When the insulator 576 is deposited by a sputtering method, a high-density silicon nitride film can be formed. To obtain the insulator 576, silicon nitride deposited by a PEALD method or a CVD method may be stacked over silicon nitride deposited by a sputtering method.
One of a first terminal and a second terminal of the transistor 500 is electrically connected to a conductor 540a serving as a plug, and the other of the first terminal and the second terminal of the transistor 500 is electrically connected to a conductor 540b. Note that in this specification and the like, the conductor 540a and the conductor 540b are collectively referred to as the conductor 540.
The conductor 540a is provided in a region overlapping with the conductor 542a, for example. Specifically, an opening portion is formed in the insulator 571, the insulator 544, the insulator 580, the insulator 574, the insulator 576, and the insulator 581 illustrated in
As illustrated in
For the conductor 540a and the conductor 540b, a conductive material containing tungsten, copper, or aluminum as its main component is preferably used. The conductor 540a and the conductor 540b may each have a stacked-layer structure.
In the case where the conductor 540 has a stacked-layer structure, a conductive material having a function of inhibiting passage of impurities such as water and hydrogen is preferably used for a first conductor provided in the vicinity of the insulator 574, the insulator 576, the insulator 581, the insulator 580, the insulator 544, and the insulator 571. For example, tantalum, tantalum nitride, titanium, titanium nitride, ruthenium, ruthenium oxide, or the like is preferably used. The conductive material having a function of inhibiting passage of impurities such as water and hydrogen may be used as a single layer or stacked layers. Moreover, impurities such as water and hydrogen contained in a layer above the insulator 576 can be inhibited from entering the oxide 530 through the conductor 540a and the conductor 540b.
For the insulator 541a and the insulator 541b, a barrier insulating film that can be used for the insulator 544 or the like may be used. For the insulator 541a and the insulator 541b, for example, an insulator such as silicon nitride, aluminum oxide, or silicon nitride oxide may be used. Since the insulator 541a and the insulator 541b are provided in contact with the insulator 574, the insulator 576, and the insulator 571, impurities such as water and hydrogen contained in the insulator 580 or the like can be inhibited from entering the oxide 530 through the conductor 540a and the conductor 540b. In particular, silicon nitride is suitable because of its high blocking property against hydrogen. Furthermore, oxygen contained in the insulator 580 can be prevented from being absorbed by the conductor 540a and the conductor 540b.
When the insulator 541a and the insulator 541b each have a stacked-layer structure as illustrated in
For example, aluminum oxide deposited by an ALD method may be used as the first insulator and silicon nitride deposited by a PEALD method may be used as the second insulator. With this structure, oxidation of the conductor 540 can be inhibited, and hydrogen can be inhibited from entering the conductor 540.
Although the first insulator of the insulator 541 and the second conductor of the insulator 541 are stacked in the transistor 500, the present invention is not limited thereto. For example, the insulator 541 may have a single-layer structure or a stacked-layer structure of three or more layers. Although the first conductor of the conductor 540 and the second conductor of the conductor 540 are stacked in the transistor 500, the present invention is not limited thereto. For example, the conductor 540 may have a single-layer structure or a stacked-layer structure of three or more layers.
As illustrated in
The structure of the transistor included in the semiconductor device of one embodiment of the present invention is not limited to that of the transistor 500 illustrated in
For example, the transistor 500 illustrated in
The oxide 543a is provided between the oxide 530b and the conductor 542a, and the oxide 543b is provided between the oxide 530b and the conductor 542b. Here, the oxide 543a is preferably in contact with the top surface of the oxide 530b and the bottom surface of the conductor 542a. The oxide 543b is preferably in contact with the top surface of the oxide 530b and the bottom surface of the conductor 542b.
The oxide 543 preferably has a function of inhibiting passage of oxygen. The oxide 543 having a function of inhibiting passage of oxygen is preferably provided between the oxide 530b and the conductor 542 functioning as the source electrode or the drain electrode, in which case the electric resistance between the conductor 542 and the oxide 530b can be reduced. Such a structure can improve the electrical characteristics, the field-effect mobility, and the reliability of the transistor 500 in some cases.
A metal oxide containing the element M may be used as the oxide 543. The concentration of the element Min the oxide 543 is preferably higher than that in the oxide 530b. Furthermore, gallium oxide may be used as the oxide 543. A metal oxide such as an In-M-Zn oxide may be used as the oxide 543. Specifically, the atomic ratio of the element M to In in the metal oxide used as the oxide is preferably greater than the atomic ratio of the element M to In in the metal oxide used as the oxide 530b. The thickness of the oxide 543 is preferably greater than or equal to 0.5 nm or greater than or equal to 1 nm, and less than or equal to 2 nm, less than or equal to 3 nm, or less than or equal to 5 nm. Note that any of the above-described lower limits and upper limits can be combined with each other. The oxide 543 preferably has crystallinity. In the case where the oxide 543 has crystallinity, release of oxygen from the oxide 530 can be suitably inhibited. When the oxide 543 has a hexagonal crystal structure, for example, release of oxygen from the oxide 530 can sometimes be inhibited.
An insulator 582 is provided over the insulator 581, and an insulator 586 is provided over the insulator 582.
A substance having a barrier property against oxygen, hydrogen, or the like is preferably used for the insulator 582. Therefore, a material similar to that for the insulator 514 can be used for the insulator 582. For example, a metal oxide such as aluminum oxide, hafnium oxide, or tantalum oxide is preferably used for the insulator 582.
For the insulator 586, a material similar to that for the insulator 320 can be used. Furthermore, when a material with a comparatively low permittivity is used for these insulators, parasitic capacitance generated between wirings can be reduced. A silicon oxide film, a silicon oxynitride film, or the like can be used for the insulator 586, for example.
Next, the capacitor 600 and peripheral wirings or plugs included in the semiconductor device illustrated in
The capacitor 600 includes, for example, a conductor 610, a conductor 620, and an insulator 630.
The conductor 610 is provided over one of the conductor 540a and the conductor 540b, the conductor 546, and the insulator 586. The conductor 610 has a function of one of the pair of electrodes of the capacitor 600.
A conductor 612 is provided over the other of the conductor 540a and the conductor 540b and the insulator 586. The conductor 612 has a function of a plug, a wiring, a terminal, or the like that electrically connects the transistor 500 to a circuit element, a wiring, a terminal, and the like that can be provided above the transistor 500. Specifically, for example, the conductor 612 can be the wiring IL or the wiring ILB in the arithmetic circuit 110 and the like described in the above embodiments.
Note that the conductor 612 and the conductor 610 may be formed at the same time.
As the conductor 612 and the conductor 610, it is possible to use a metal film containing an element selected from molybdenum, titanium, tantalum, tungsten, aluminum, copper, chromium, neodymium, and scandium; a metal nitride film containing any of the above elements as its component (a tantalum nitride film, a titanium nitride film, a molybdenum nitride film, or a tungsten nitride film); or the like. Alternatively, it is possible to use a conductive material such as indium tin oxide, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium zinc oxide, or indium tin oxide to which silicon oxide is added.
The conductor 612 and the conductor 610 each have a single-layer structure in
The insulator 630 is provided over the insulator 586 and the conductor 610. The insulator 630 serves as a dielectric sandwiched between the pair of electrodes of the capacitor 600.
The insulator 630 can be provided to have a single-layer structure or a stacked-layer structure using, for example, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum oxynitride, aluminum nitride oxide, aluminum nitride, hafnium oxide, hafnium oxynitride, hafnium nitride oxide, hafnium nitride, or zirconium oxide.
Alternatively, for the insulator 630, a stacked-layer structure using a material with high dielectric strength, such as silicon oxynitride, and a high permittivity (high-k) material may be used, for example. In the capacitor 600 having such a structure, a sufficient capacitance can be ensured owing to the high permittivity (high-k) insulator, and the dielectric strength can be increased owing to the insulator with high dielectric strength; hence, the electrostatic breakdown of the capacitor 600 can be inhibited.
Examples of the insulator of a high permittivity (high-k) material (high dielectric constant material) include gallium oxide, hafnium oxide, zirconium oxide, an oxide containing aluminum and hafnium, an oxynitride containing aluminum and hafnium, an oxide containing silicon and hafnium, an oxynitride containing silicon and hafnium, and a nitride containing silicon and hafnium.
Alternatively, for example, a single layer or stacked layers of an insulator containing a high-k material such as aluminum oxide, hafnium oxide, tantalum oxide, zirconium oxide, lead zirconate titanate (PZT), strontium titanate (SrTiO3), or (Ba,Sr)TiO3 (BST) may be used as the insulator 630. For the insulator 630, a compound containing hafnium and zirconium may be used, for example. As miniaturization and high integration of semiconductor devices progress, a problem such as a leakage current from a transistor and a capacitor might arise because of a thinner gate insulator and a thinner dielectric used in the capacitor. When a high-k material is used as a gate insulator and an insulator functioning as a dielectric used in a capacitor, a gate potential during operation of the transistor can be lowered and capacitance of the capacitor can be ensured while the physical thickness is maintained.
The conductor 620 is provided to overlap with the conductor 610 with the insulator 630 therebetween. The conductor 620 has a function of the other of the pair of electrodes of the capacitor 600. For example, the conductor 620 can be the wiring XLS of the arithmetic circuit 110 and the like described in the above embodiments.
For the conductor 620, a conductive material such as a metal material, an alloy material, or a metal oxide material can be used. It is preferable to use a high-melting-point material that has both heat resistance and conductivity, such as tungsten or molybdenum, and it is particularly preferable to use tungsten. In the case where the conductor 620 is formed concurrently with another component such as a conductor, Cu (copper), Al (aluminum), or the like, which is a low-resistance metal material, is used. Moreover, the conductor 620 can be formed using a material that can be used for the conductor 610, for example. Furthermore, the conductor 620 may have a stacked-layer structure of two or more layers, instead of a single-layer structure.
An insulator 640 is provided over the conductor 620 and the insulator 630. As the insulator 640, a film having a barrier property that prevents diffusion of hydrogen or impurities into the region where the transistor 500 is formed is preferably used, for example. Thus, a material similar to that for the insulator 324 can be used.
An insulator 650 is provided over the insulator 640. The insulator 650 can be provided using a material similar to that for the insulator 320. The insulator 650 may function as a planarization film that covers an uneven shape thereunder. Thus, the insulator 650 can be formed using any of the materials usable for the insulator 322, for example.
Although the capacitor 600 illustrated in
A wiring layer may be provided above the capacitor 600. For example, in
In the insulator 630, the insulator 640, and the insulator 650, an opening portion is provided in a region overlapping with the conductor 612, and the conductor 660 is provided to fill the opening portion. The conductor 660 serves as a plug or a wiring that is electrically connected to the conductor 416 included in the above-described wiring layer.
Like the insulator 324 or the like, the insulator 411 and the insulator 414 are preferably formed using an insulator having a barrier property against impurities such as water and hydrogen, for example. Thus, the insulator 411 and the insulator 414 can be formed using any of the materials usable for the insulator 324 or the like, for example.
Like the insulator 326, the insulator 412 and the insulator 413 are preferably formed using an insulator having a relatively low dielectric constant to reduce the parasitic capacitance generated between wirings, for example.
The conductor 612 and the conductor 416 can be provided using materials similar to those for the conductor 328 and the conductor 330, for example.
When a semiconductor device using a transistor including an oxide semiconductor has the structure described in this embodiment, a change in electrical characteristics of the transistor can be inhibited and the reliability can be improved. Alternatively, a semiconductor device using a transistor including an oxide semiconductor can be miniaturized or highly integrated.
Note that this embodiment can be combined with any of the other embodiments in this specification as appropriate.
Described in this embodiment is a metal oxide (hereinafter also referred to as an oxide semiconductor) that can be used in the OS transistor described in the above embodiment.
The metal oxide preferably contains at least indium or zinc. It is particularly preferable that indium and zinc be contained. In addition, aluminum, gallium, yttrium, tin, or the like is preferably contained. Furthermore, one or more kinds selected from boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, cobalt, and the like may be contained.
First, classification of the crystal structures of an oxide semiconductor is described using
As shown in
Note that the structures in the thick frame in
Note that a crystal structure of a film or a substrate can be evaluated with an X-ray diffraction (XRD) spectrum.
As shown in
A crystal structure of a film or a substrate can also be evaluated with a diffraction pattern obtained by a nanobeam electron diffraction method (NBED) (such a pattern is also referred to as a nanobeam electron diffraction pattern).
As shown in
Oxide semiconductors might be classified in a manner different from one shown in
Here, the above-described CAAC-OS, nc-OS, and a-like OS are described in detail.
The CAAC-OS is an oxide semiconductor that has a plurality of crystal regions each of which has c-axis alignment in a particular direction. Note that the particular direction refers to the thickness direction of a CAAC-OS film, the normal direction of the surface where the CAAC-OS film is formed, or the normal direction of the surface of the CAAC-OS film. The crystal region refers to a region having a periodic atomic arrangement. When an atomic arrangement is regarded as a lattice arrangement, the crystal region also refers to a region with a uniform lattice arrangement. The CAAC-OS has a region where a plurality of crystal regions are connected in the a-b plane direction, and the region has distortion in some cases. Note that distortion refers to a portion where the direction of a lattice arrangement changes between a region with a uniform lattice arrangement and another region with a uniform lattice arrangement in a region where a plurality of crystal regions are connected. That is, the CAAC-OS is an oxide semiconductor having c-axis alignment and having no clear alignment in the a-b plane direction.
Note that each of the plurality of crystal regions is formed of one or more minute crystals (crystals each of which has a maximum diameter of less than 10 nm). In the case where the crystal region is formed of one minute crystal, the maximum diameter of the crystal region is less than 10 nm. In the case where the crystal region is formed of a large number of minute crystals, the size of the crystal region may be approximately several tens of nanometers.
In the case of an In-M-Zn oxide (the element M is one or more kinds selected from aluminum, gallium, yttrium, tin, titanium, and the like), the CAAC-OS tends to have a layered crystal structure (also referred to as a layered structure) in which a layer containing indium (In) and oxygen (hereinafter, an In layer) and a layer containing the element M, zinc (Zn), and oxygen (hereinafter, an (M,Zn) layer) are stacked. Indium and the element M can be replaced with each other. Therefore, indium may be contained in the (M,Zn) layer. In addition, the element M may be contained in the In layer. Note that Zn may be contained in the In layer. Such a layered structure is observed as a lattice image in a high-resolution TEM image, for example.
When the CAAC-OS film is subjected to structural analysis by out-of-plane XRD measurement with an XRD apparatus using θ/2θ scanning, for example, a peak indicating c-axis alignment is detected at 2θ of 31° or around 31°. Note that the position of the peak indicating c-axis alignment (the value of 2θ) may change depending on the kind, composition, or the like of the metal element contained in the CAAC-OS.
For example, a plurality of bright spots are observed in the electron diffraction pattern of the CAAC-OS film. Note that one spot and another spot are observed point-symmetrically with a spot of the incident electron beam passing through a sample (also referred to as a direct spot) as the symmetric center.
When the crystal region is observed from the particular direction, a lattice arrangement in the crystal region is basically a hexagonal lattice arrangement; however, a unit lattice is not always a regular hexagon and is a non-regular hexagon in some cases. A pentagonal lattice arrangement, a heptagonal lattice arrangement, and the like are included in the distortion in some cases. Note that a clear crystal grain boundary (also referred to as grain boundary) cannot be observed even in the vicinity of the distortion in the CAAC-OS. That is, formation of a crystal grain boundary is inhibited by the distortion of lattice arrangement. This is probably because the CAAC-OS can tolerate distortion owing to a low density of arrangement of oxygen atoms in the a-b plane direction, an interatomic bond distance changed by substitution of a metal atom, and the like.
Note that a crystal structure in which a clear crystal grain boundary is observed is what is called polycrystal. It is highly probable that the crystal grain boundary becomes a recombination center and traps carriers and thus decreases the on-state current and field-effect mobility of a transistor, for example. Thus, the CAAC-OS in which no clear crystal grain boundary is observed is one of crystalline oxides having a crystal structure suitable for a semiconductor layer of a transistor. Note that Zn is preferably contained to form the CAAC-OS. For example, an In—Zn oxide and an In—Ga—Zn oxide are suitable because they can inhibit generation of a crystal grain boundary as compared with an In oxide.
The CAAC-OS is an oxide semiconductor with high crystallinity in which no clear crystal grain boundary is observed. Thus, in the CAAC-OS, a reduction in electron mobility due to the crystal grain boundary is unlikely to occur. Moreover, since the crystallinity of an oxide semiconductor might be decreased by entry of impurities, formation of defects, or the like, the CAAC-OS can be regarded as an oxide semiconductor that has a small amount of impurities and defects (e.g., oxygen vacancies). Thus, an oxide semiconductor including the CAAC-OS is physically stable. Therefore, the oxide semiconductor including the CAAC-OS is resistant to heat and has high reliability. In addition, the CAAC-OS is stable with respect to high temperature in the manufacturing process (what is called thermal budget). Accordingly, the use of the CAAC-OS for the OS transistor can extend the degree of freedom of the manufacturing process.
[nc-OS]
In the nc-OS, a microscopic region (e.g., a region with a size greater than or equal to 1 nm and less than or equal to 10 nm, in particular, a region with a size greater than or equal to 1 nm and less than or equal to 3 nm) has a periodic atomic arrangement. In other words, the nc-OS includes a minute crystal. Note that the size of the minute crystal is, for example, greater than or equal to 1 nm and less than or equal to 10 nm, particularly greater than or equal to 1 nm and less than or equal to 3 nm; thus, the minute crystal is also referred to as a nanocrystal. Furthermore, there is no regularity of crystal orientation between different nanocrystals in the nc-OS. Thus, the orientation in the whole film is not observed. Accordingly, the nc-OS cannot be distinguished from an a-like OS or an amorphous oxide semiconductor by some analysis methods. For example, when an nc-OS film is subjected to structural analysis by out-of-plane XRD measurement with an XRD apparatus using θ/2θ scanning, a peak indicating crystallinity is not detected. Furthermore, a diffraction pattern like a halo pattern is observed when the nc-OS film is subjected to electron diffraction (also referred to as selected-area electron diffraction) using an electron beam with a probe diameter larger than the diameter of a nanocrystal (e.g., larger than or equal to 50 nm). Meanwhile, in some cases, a plurality of spots in a ring-like region with a direct spot as the center are observed in the obtained electron diffraction pattern when the nc-OS film is subjected to electron diffraction (also referred to as nanobeam electron diffraction) using an electron beam with a probe diameter nearly equal to or smaller than the diameter of a nanocrystal (e.g., 1 nm or larger and 30 nm or smaller).
[a-Like OS]
The a-like OS is an oxide semiconductor having a structure between those of the nc-OS and the amorphous oxide semiconductor. The a-like OS includes a void or a low-density region. That is, the a-like OS has lower crystallinity than the nc-OS and the CAAC-OS. Moreover, the a-like OS has a higher hydrogen concentration in the film than the nc-OS and the CAAC-OS.
Next, the above-described CAC-OS is described in detail. Note that the CAC-OS relates to the material composition.
The CAC-OS refers to one composition of a material in which elements constituting a metal oxide are unevenly distributed with a size greater than or equal to 0.5 nm and less than or equal to 10 nm, preferably greater than or equal to 1 nm and less than or equal to 3 nm, or a similar size, for example. Note that a state in which one or more metal elements are unevenly distributed and regions including the metal element(s) are mixed with a size greater than or equal to 0.5 nm and less than or equal to 10 nm, preferably greater than or equal to 1 nm and less than or equal to 3 nm, or a similar size in a metal oxide is hereinafter referred to as a mosaic pattern or a patch-like pattern.
In addition, the CAC-OS has a composition in which materials are separated into a first region and a second region to form a mosaic pattern, and the first regions are distributed in the film (this composition is hereinafter also referred to as a cloud-like composition). That is, the CAC-OS is a composite metal oxide having a composition in which the first regions and the second regions are mixed.
Here, the atomic ratios of In, Ga, and Zn to the metal elements contained in the CAC-OS in an In—Ga—Zn oxide are denoted by [In], [Ga], and [Zn], respectively. For example, the first region in the CAC-OS in the In—Ga—Zn oxide has [In] higher than [In] in the composition of the CAC-OS film. Moreover, the second region has [Ga] higher than [Ga] in the composition of the CAC-OS film. Alternatively, for example, the first region has [In] higher than [In] in the second region and [Ga] lower than [Ga] in the second region. Moreover, the second region has [Ga] higher than [Ga] in the first region and [In] lower than [In] in the first region.
Specifically, the first region contains indium oxide, indium zinc oxide, or the like as its main component. The second region contains gallium oxide, gallium zinc oxide, or the like as its main component. That is, the first region can be rephrased as a region containing In as its main component. The second region can be rephrased as a region containing Ga as its main component.
Note that a clear boundary between the first region and the second region cannot be observed in some cases.
For example, in EDX mapping obtained by energy dispersive X-ray spectroscopy (EDX), it is confirmed that the CAC-OS in the In—Ga—Zn oxide has a structure in which the region containing In as its main component (the first region) and the region containing Ga as its main component (the second region) are unevenly distributed and mixed.
In the case where the CAC-OS is used for a transistor, a switching function (On/Off switching function) can be given to the CAC-OS owing to the complementary action of the conductivity derived from the first region and the insulating property derived from the second region. That is, the CAC-OS has a conducting function in part of the material and has an insulating function in another part of the material; as a whole, the CAC-OS has a function of a semiconductor. Separation of the conducting function and the insulating function can maximize each function. Accordingly, when the CAC-OS is used for a transistor, a high on-state current (Ion), high field-effect mobility (μ), and excellent switching operation can be achieved.
An oxide semiconductor has various structures with different properties. Two or more kinds among the amorphous oxide semiconductor, the polycrystalline oxide semiconductor, the a-like OS, the CAC-OS, the nc-OS, and the CAAC-OS may be included in an oxide semiconductor of one embodiment of the present invention.
Next, the case where the above oxide semiconductor is used for a transistor is described.
When the above oxide semiconductor is used for a transistor, a transistor with high field-effect mobility can be achieved. In addition, a transistor having high reliability can be achieved.
An oxide semiconductor having a low carrier concentration is preferably used in a transistor. For example, the carrier concentration of an oxide semiconductor is lower than or equal to 1×1017 cm−3, preferably lower than or equal to 1×1015 cm−3, further preferably lower than or equal to 1×1013 cm−3, still further preferably lower than or equal to 1×1011 cm−3, yet further preferably lower than 1×1010 cm−3, and higher than or equal to 1×10−9 cm−3. In order to reduce the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film is reduced so that the density of defect states can be reduced. In this specification and the like, a state with a low impurity concentration and a low density of defect states is referred to as a highly purified intrinsic or substantially highly purified intrinsic state. Note that an oxide semiconductor having a low carrier concentration may be referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor.
A highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has a low density of defect states and thus also has a low density of trap states in some cases.
Charge trapped by the trap states in the oxide semiconductor takes a long time to disappear and might behave like fixed charge. Thus, a transistor whose channel formation region is formed in an oxide semiconductor with a high density of trap states has unstable electrical characteristics in some cases.
Accordingly, in order to obtain stable electrical characteristics of a transistor, reducing the impurity concentration in an oxide semiconductor is effective. In order to reduce the impurity concentration in the oxide semiconductor, it is preferable that the impurity concentration in an adjacent film be also reduced. Examples of impurities include hydrogen, nitrogen, an alkali metal, an alkaline earth metal, iron, nickel, and silicon.
Here, the influence of each impurity in the oxide semiconductor is described.
When silicon or carbon, which is one of Group 14 elements, is contained in the oxide semiconductor, defect states are formed in the oxide semiconductor. Thus, the concentration of silicon or carbon in the oxide semiconductor and the concentration of silicon or carbon in the vicinity of an interface with the oxide semiconductor (the concentration obtained by secondary ion mass spectrometry (SIMS)) are each set lower than or equal to 2×1018 atoms/cm3, preferably lower than or equal to 2×1017 atoms/cm3.
When the oxide semiconductor contains an alkali metal or an alkaline earth metal, defect states are formed and carriers are generated in some cases. Thus, a transistor using an oxide semiconductor that contains an alkali metal or an alkaline earth metal is likely to have normally-on characteristics. Hence, the concentration of an alkali metal or an alkaline earth metal in the oxide semiconductor, which is obtained by SIMS, is set lower than or equal to 1×1018 atoms/cm3, preferably lower than or equal to 2×1016 atoms/cm3.
When the oxide semiconductor contains nitrogen, the oxide semiconductor easily becomes n-type by generation of electrons serving as carriers and an increase in carrier concentration. As a result, a transistor using an oxide semiconductor containing nitrogen as a semiconductor is likely to have normally-on characteristics. When nitrogen is contained in the oxide semiconductor, a trap state is sometimes formed. This might make the electrical characteristics of the transistor unstable. Therefore, the concentration of nitrogen in the oxide semiconductor, which is obtained by SIMS, is set lower than 5×1019 atoms/cm3, preferably lower than or equal to 5×1018 atoms/cm3, further preferably lower than or equal to 1×1018 atoms/cm3, still further preferably lower than or equal to 5×1017 atoms/cm3.
Hydrogen contained in the oxide semiconductor reacts with oxygen bonded to a metal atom to be water, and thus forms an oxygen vacancy in some cases. Entry of hydrogen into the oxygen vacancy generates an electron serving as a carrier in some cases. Furthermore, bonding of part of hydrogen to oxygen bonded to a metal atom causes generation of an electron serving as a carrier in some cases. Thus, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. Accordingly, hydrogen in the oxide semiconductor is preferably reduced as much as possible. Specifically, the hydrogen concentration in the oxide semiconductor, which is obtained by SIMS, is set lower than 1×1020 atoms/cm3, preferably lower than 1×1019 atoms/cm3, further preferably lower than 5×1018 atoms/cm3, still further preferably lower than 1×1018 atoms/cm3.
When an oxide semiconductor with sufficiently reduced impurities is used for the channel formation region of the transistor, stable electrical characteristics can be given.
Note that this embodiment can be combined with any of the other embodiments in this specification as appropriate.
This embodiment will show examples of a semiconductor wafer where the semiconductor device or the like described in the above embodiment is formed and electronic components incorporating the semiconductor device.
First, an example of a semiconductor wafer provided with a semiconductor device or the like is described with reference to
A semiconductor wafer 4800 illustrated in
The semiconductor wafer 4800 can be fabricated by forming the plurality of circuit portions 4802 on the surface of the wafer 4801 by a pre-process. After that, a surface of the wafer 4801 opposite to the surface provided with the plurality of circuit portions 4802 may be ground to thin the wafer 4801. Through this step, warpage or the like of the wafer 4801 is reduced and the size of the component can be reduced.
A dicing step is performed as the next step. The dicing is performed along scribe lines SCL1 and scribe lines SCL2 (referred to as dicing lines or cutting lines in some cases) indicated by dashed-dotted lines. Note that to perform the dicing step easily, it is preferable that the spacing 4803 be provided such that the plurality of scribe lines SCL1 are parallel to each other, the plurality of scribe lines SCL2 are parallel to each other, and the scribe lines SCL1 are perpendicular to the scribe lines SCL2.
With the dicing step, a chip 4800a illustrated in
Note that the shape of the element substrate of one embodiment of the present invention is not limited to the shape of the semiconductor wafer 4800 illustrated in
The electronic component 4730 includes the semiconductor devices 4710. Examples of the semiconductor devices 4710 include the semiconductor devices described in the above embodiments and a high bandwidth memory (HBM). An integrated circuit (a semiconductor device) such as a CPU, a GPU, an FPGA, or a memory device can be used as the semiconductor device 4735.
As the package substrate 4732, a ceramic substrate, a plastic substrate, a glass epoxy substrate, or the like can be used. As the interposer 4731, a silicon interposer, a resin interposer, or the like can be used.
The interposer 4731 includes a plurality of wirings and has a function of electrically connecting a plurality of integrated circuits with different terminal pitches. The plurality of wirings are provided in a single layer or multiple layers. Moreover, the interposer 4731 has a function of electrically connecting an integrated circuit provided on the interposer 4731 to an electrode provided on the package substrate 4732. Accordingly, the interposer is referred to as a “redistribution substrate” or an “intermediate substrate” in some cases. A through electrode is provided in the interposer 4731 and the through electrode is used to electrically connect an integrated circuit and the package substrate 4732 in some cases. In the case of using a silicon interposer, a TSV (Through Silicon Via) can also be used as the through electrode.
A silicon interposer is preferably used as the interposer 4731. A silicon interposer can be manufactured at lower cost than an integrated circuit because it is not necessary to provide an active element. Meanwhile, since wirings of a silicon interposer can be formed through a semiconductor process, formation of minute wirings, which is difficult for a resin interposer, is easy.
In order to achieve a wide memory bandwidth, many wirings need to be connected to an HBM. Therefore, formation of minute and high-density wirings is required for an interposer on which an HBM is mounted. For this reason, a silicon interposer is preferably used as the interposer on which an HBM is mounted.
In a SiP, an MCM, or the like using a silicon interposer, a decrease in reliability due to a difference in expansion coefficient between an integrated circuit and the interposer is less likely to occur. Furthermore, the surface of a silicon interposer has high planarity, so that a poor connection between the silicon interposer and an integrated circuit provided on the silicon interposer is less likely to occur. It is particularly preferable to use a silicon interposer for a 2.5D package (2.5-dimensional mounting) in which a plurality of integrated circuits are arranged side by side on an interposer.
A heat sink (a radiator plate) may be provided to overlap with the electronic component 4730. In the case of providing a heat sink, the heights of integrated circuits provided on the interposer 4731 are preferably equal to each other. For example, in the electronic component 4730 described in this embodiment, the heights of the semiconductor devices 4710 and the semiconductor device 4735 are preferably equal to each other.
To mount the electronic component 4730 on another substrate, an electrode 4733 may be provided on the bottom portion of the package substrate 4732.
The electronic component 4730 can be mounted on another substrate by various mounting methods other than BGA and PGA. For example, a mounting method such as SPGA (Staggered Pin Grid Array), LGA (Land Grid Array), QFP (Quad Flat Package), QFJ (Quad Flat J-leaded package), or QFN (Quad Flat Non-leaded package) can be employed.
Note that this embodiment can be combined with any of the other embodiments in this specification as appropriate.
This embodiment will show examples of electronic devices each including the semiconductor device described in the above embodiment.
An information terminal 5500 illustrated in
The information terminal 5500 can execute an application utilizing artificial intelligence with the use of the semiconductor device described in the above embodiment. Examples of the application utilizing artificial intelligence include an application for interpreting a conversation and displaying its content on the display portion 5511; an application for recognizing letters, diagrams, and the like input to the touch panel of the display portion 5511 by a user and displaying them on the display portion 5511; and an application for biometric authentication using fingerprints, voice prints, or the like. As another example, when an image is obtained by an imaging device (not illustrated) provided in the information terminal 5500, the use of the semiconductor device described in the above embodiment enables convolutional processing on the image. In other words, feature extraction can be performed on the image.
The wearable terminal can execute an application utilizing artificial intelligence with the use of the semiconductor device described in the above embodiment, like the information terminal 5500. Examples of the application utilizing artificial intelligence include an application for managing the health condition of the user of the wearable terminal and a navigation system that selects the optimal route and navigates the user on the basis of the input of the destination.
The desktop information terminal 5300 can execute an application utilizing artificial intelligence with the use of the semiconductor device described in the above embodiment, like the information terminal 5500. Examples of the application utilizing artificial intelligence include design-support software, text correction software, and software for automatic menu generation. Furthermore, with the use of the desktop information terminal 5300, novel artificial intelligence can be developed. As another example, when an image is obtained by an imaging device (not illustrated) provided in the information terminal 5500, the use of the semiconductor device described in the above embodiment enables convolutional processing on the image. In other words, feature extraction can be performed on the image.
Note that although
When the semiconductor device described in the above embodiment is used in the electric refrigerator-freezer 5800, the electric refrigerator-freezer 5800 including artificial intelligence can be achieved. Utilizing the artificial intelligence enables the electric refrigerator-freezer 5800 to have a function of automatically making a menu based on foods stored in the electric refrigerator-freezer 5800, expiration dates of the foods, or the like, a function of automatically adjusting temperature to be appropriate for the foods stored in the electric refrigerator-freezer 5800, and the like.
Although the electric refrigerator-freezer is described as a household appliance in this example, other examples of the household appliance include a vacuum cleaner, a microwave oven, an electric oven, a rice cooker, a water heater, an IH (Induction Heating) cooker, a water server, a heating-cooling combination appliance such as an air conditioner, a washing machine, a drying machine, and an audio visual appliance.
A video of the game machine can be output with a display device such as a television device, a personal computer display, a game display, or a head-mounted display.
When the semiconductor device described in the above embodiment is used in the portable game machine 5200, the portable game machine 5200 with low power consumption can be achieved. Moreover, heat generation from a circuit can be reduced owing to low power consumption; thus, the influence of heat generation on the circuit itself, the peripheral circuit, and the module can be reduced.
Furthermore, when the semiconductor device described in the above embodiment is used for the portable game machine 5200, the portable game machine 5200 including artificial intelligence can be achieved.
In general, the progress of a game, the actions and words of game characters, and expressions of a phenomenon and the like in the game are programed in the game; however, the use of artificial intelligence in the portable game machine 5200 enables expressions not limited by the game program. For example, it becomes possible to change expressions such as questions posed by the player, the progress of the game, time, and actions and words of game characters.
When a game requiring a plurality of players is played on the portable game machine 5200, the artificial intelligence can create a virtual game player; thus, the game can be played alone with the game player created by the artificial intelligence as an opponent.
Although
The semiconductor device described in the above embodiment can be used for an automobile, which is a moving vehicle, and around the driver's seat in an automobile.
An instrument panel that can display a speedometer, a tachometer, a mileage, a fuel meter, a gearshift state, air-conditioning setting, and the like is provided around the driver's seat in the automobile 5700. In addition, a display device showing the above information may be provided around the driver's seat.
In particular, the display device can compensate for the view obstructed by the pillar or the like, the blind areas for the driver's seat, and the like by displaying a video taken by an imaging device (not illustrated) provided for the automobile 5700, thereby providing a high level of safety. That is, display of an image taken by an imaging device provided on the outside of the automobile 5700 can compensate for blind areas and enhance safety.
Since the semiconductor device described in the above embodiment can be used as the components of artificial intelligence, the semiconductor device can be used for an automatic driving system of the automobile 5700, for example. The semiconductor device can also be used for a system for navigation, risk prediction, or the like. The display device may display navigation information, risk prediction information, or the like.
Note that although an automobile is described above as an example of a moving vehicle, the moving vehicle is not limited to an automobile. Examples of the moving vehicle include a train, a monorail train, a ship, and a flying object (a helicopter, an unmanned aircraft (a drone), an airplane, and a rocket), and these moving vehicles can include a system utilizing artificial intelligence when equipped with the semiconductor device of one embodiment of the present invention.
The semiconductor device described in the above embodiment can be used for a camera.
When the semiconductor device described in the above embodiment is used in the digital camera 6240, the digital camera 6240 with low power consumption can be achieved. Moreover, heat generation from a circuit can be reduced owing to low power consumption; thus, the influence of heat generation on the circuit itself, the peripheral circuit, and the module can be reduced.
Furthermore, when the semiconductor device described in the above embodiment is used in the digital camera 6240, the digital camera 6240 including artificial intelligence can be achieved. Utilizing the artificial intelligence enables the digital camera 6240 to have a function of automatically recognizing a subject such as a face or an object, a function of adjusting a focus on the subject, a function of automatically using a flash in accordance with environments, a function of toning a taken image, and the like. For example, when an image is obtained by the digital camera 6240, the use of the semiconductor device described in the above embodiment enables convolutional processing on the image. In other words, feature extraction can be performed on the image.
The semiconductor device described in the above embodiment can be used for a video camera.
When videos taken by the video camera 6300 are recorded, the videos need to be encoded in accordance with a data recording format. With the use of artificial intelligence, the video camera 6300 can perform the pattern recognition by artificial intelligence in encoding of the videos. By the pattern recognition, difference data on a person, an animal, an object, and the like included in continuously taken image data is calculated, so that the data can be compressed. Moreover, for example, convolutional processing may be performed on the taken image data by using the semiconductor device described in the above embodiment.
The semiconductor device described in the above embodiment can be used in a calculator such as a PC (Personal Computer) and an expansion device for an information terminal.
The expansion device 6100 includes a housing 6101, a cap 6102, a USB connector 6103, and a substrate 6104. The substrate 6104 is held in the housing 6101. The substrate 6104 is provided with a circuit for driving the semiconductor device or the like described in the above embodiment. For example, a chip 6105 (e.g., the semiconductor device described in the above embodiment, the electronic component 4700, or a memory chip) and a controller chip 6106 are attached to the substrate 6104. The USB connector 6103 functions as an interface for connection to an external device.
The use of the expansion device 6100 for a PC and the like can increase the arithmetic processing performance of the PC. Thus, a PC with insufficient processing performance can perform arithmetic operation of artificial intelligence, moving image processing, and the like.
The semiconductor device described in the above embodiment can be used for a broadcasting system.
Although a UHF (Ultra High Frequency) antenna is illustrated as the antenna 5650 in
A radio wave 5675A and a radio wave 5675B are broadcasting signals for terrestrial broadcasting; a radio wave tower 5670 amplifies the received radio wave 5675A and transmits the radio wave 5675B. Each household can view terrestrial TV broadcasting on the TV 5600 by receiving the radio wave 5675B with the antenna 5650. Note that the broadcasting system is not limited to the terrestrial broadcasting illustrated in
The above-described broadcasting system may be a broadcasting system that utilizes artificial intelligence by including the semiconductor device described in the above embodiment. When the broadcast data is transmitted from the broadcast station 5680 to the TV 5600 of each household, the broadcast data is compressed with an encoder. When the antenna 5650 receives the compressed broadcast data, the compressed broadcast data is decompressed with a decoder of the receiving device in the TV 5600. Utilizing the artificial intelligence enables, for example, recognition of a display pattern included in a displayed image in motion compensation prediction, which is one of the compressing methods for the encoder. In-frame prediction utilizing artificial intelligence, for example, can also be performed. As another example, when the broadcast data with low resolution is received and the broadcast data is displayed on the TV 5600 with high resolution, image interpolation such as upconversion can be performed in the broadcast data decompression by the decoder.
The above-described broadcasting system utilizing artificial intelligence is suitable for ultra-high definition television (UHDTV: 4K and 8K) broadcasting, which needs a large amount of broadcast data.
As the application of artificial intelligence in the TV 5600, a recording device with artificial intelligence may be provided in the TV 5600, for example. With such a structure, the artificial intelligence can learn the user's preference, so that TV programs that suit the user's preference can be recorded automatically in the recording device.
The semiconductor device described in the above embodiment can be used for an authentication system.
In
Note that this embodiment can be combined with any of the other embodiments in this specification as appropriate.
ILD: circuit, WLD: circuit, XLD: circuit, AFP: circuit, ACTF: circuit, MP: circuit, MC: circuit, MCr: circuit, M1: transistor, M1-2b: transistor, M1-2br: transistor, M1-3b: transistor, M1-3br: transistor, M1c: transistor, M1cr: transistor, M1p: transistor, M1pr: transistor, M1r: transistor, M1s: transistor, M1sr: transistor, M1x: transistor, M1xr: transistor, M1x-2b: transistor, M1x-2br: transistor, M1x-3b: transistor, M1x-3br: transistor, M1-2x: transistor, M1-2xr: transistor, M1-3x: transistor, M1-3xr: transistor, M1-2x-2b: transistor, M1-2x-2br: transistor, M1-3x-2b: transistor, M1-3x-2br: transistor, M1-2x-3b: transistor, M1-2x-3br: transistor, M1-3x-3b: transistor, M1-3x-3br: transistor, M2: transistor, M2r: transistor, M2s: transistor, M2sr: transistor, M2-2b: transistor, M2-2br: transistor, M2-3b: transistor, M2-3br: transistor, M3: transistor, M3p: transistor, M3pr: transistor, M3r: transistor, M3s: transistor, M3sr: transistor, M3x: transistor, M3-2b: transistor, M3-2br: 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wiring, VFr: wiring, VrefL: wiring, VL: wiring, VLr: wiring, VLs: wiring, VLsr: wiring, VLm: wiring, VEH: wiring, S1L: wiring, S2L: wiring, Vref1L: wiring, Vref2L: wiring, WL: wiring, W1L: wiring, W2L: wiring, WL2b: wiring, WL3b: wiring, WXL: wiring, WX1L: wiring, WX1L2b: wiring, WX1L3b: wiring, WX1LB: wiring, X1: wiring, X1L: wiring, X1L2b: wiring, X1L2x: wiring, X1L3b: wiring, X1L3x: wiring, X2L: wiring, X2L2b: wiring, X2L2x: wiring, X2L3b: wiring, X2L3x: wiring, X2LB: wiring, CVL: wiring, SCL1: scribe line, SCL2: scribe line, 100: neural network, 110: arithmetic circuit, 120: arithmetic circuit, 130: arithmetic circuit, 140: arithmetic circuit, 150: arithmetic circuit, 160: arithmetic circuit, 170: arithmetic circuit, 300: transistor, 310: substrate, 310A: substrate, 312: element isolation layer, 313: semiconductor region, 314a: low-resistance region, 314b: low-resistance region, 315: insulator, 316: conductor, 320: insulator, 322: insulator, 324: insulator, 326: insulator, 328: conductor, 330: conductor, 350: insulator, 352: insulator, 354: insulator, 356: conductor, 360: insulator, 362: insulator, 364: insulator, 366: conductor, 411: insulator, 412: insulator, 413: insulator, 414: insulator, 416: conductor, 500: transistor, 503: conductor, 503a: conductor, 503b: conductor, 510: insulator, 512: insulator, 514: insulator, 516: insulator, 518: conductor, 522: insulator, 524: insulator, 530: oxide, 530a: oxide, 530b: oxide, 530ba: region, 530bb: region, 530bc: region, 540a: conductor, 540b: conductor, 541a: insulator, 541b: insulator, 542a: conductor, 542b: conductor, 543a: oxide, 543b: oxide, 544: insulator, 546: conductor, 550: insulator, 550a: insulator, 550b: insulator, 552: insulator, 554: insulator, 560: conductor, 560a: conductor, 560b: conductor, 571a: insulator, 571b: insulator, 574: insulator, 576: insulator, 580: insulator, 581: insulator, 582: insulator, 586: insulator, 600: capacitor, 610: conductor, 612: conductor, 620: conductor, 630: insulator, 640: insulator, 650: insulator, 660: conductor, 4700: electronic component, 4702: printed circuit board, 4704: mounting board, 4710: semiconductor device, 4711: mold, 4712: land, 4713: electrode pad, 4714: wire, 4730: electronic component, 4731: interposer, 4732: package substrate, 4733: electrode, 4735: semiconductor device, 4800: semiconductor wafer, 4800a: chip, 4801: wafer, 4801a: wafer, 4802: circuit portion, 4803: spacing, 4803a: spacing, 5200: portable game machine, 5201: housing, 5202: display portion, 5203: button, 5300: desktop information terminal, 5301: main body, 5302: display 5303: keyboard, 5500: information terminal, 5510: housing, 5511: display portion, 5600: TV, 5650: antenna, 5670: radio wave tower, 5675A: radio wave, 5675B: radio wave, 5680: broadcast station, 5700: automobile, 5800: electric refrigerator-freezer, 5801: housing, 5802: refrigerator door, 5803: freezer door, 5900: information terminal, 5901: housing, 5902: display portion, 5903: operation button, 5904: operator, 5905: band, 6100: expansion device, 6101: housing, 6102: cap, 6103: USB connector, 6104: substrate, 6105: chip, 6106: controller chip, 6240: digital camera, 6241: housing, 6242: display portion, 6243: operation button, 6244: shutter button, 6246: lens, 6300: video camera, 6301: first housing, 6302: second housing, 6303: display portion, 6304: operation key, 6305: lens, 6306: joint, 6431: housing, 6432: display portion, 6433: palm print reading portion, 6434: wiring, 6435: hand, 7500: stationary game machine, 7520: main body, 7522: controller
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-122594 | Jul 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2021/056024 | 7/6/2021 | WO |
