The present invention generally relates to a semiconductor integrated circuit device, and more particularly to a semiconductor integrated circuit device having an improved arrangement for power supply terminals and ground terminals.
A semiconductor integrated circuit device receives electric power and ground voltage from an external power source. Thus, the semiconductor integrated circuit device has a number of terminals for receiving electric power and for receiving the ground voltage. If the semiconductor integrated circuit device is designed to send and receive signals to and from an external device, the semiconductor integrated circuit device also has a number of terminals for electrical connection to the external device. The power supply terminals and ground terminals of the semiconductor integrated circuit device are necessary for receiving drive voltage and current, and also for other purposes. For example, circuit for dealing with electrostatic discharge (ESD) and/or a bypass capacitor for dealing with noises is provided in cell areas of the power supply terminals and/or ground terminals. Thus, the power supply terminals and ground terminals are not mere “electricity receiving terminals.” The terminals have other important roles.
The semiconductor integrated circuit device often includes an internal circuit, which may include one or more logic circuits. If the number of power supply terminals and/or ground terminals is insufficient, the internal circuit in the semiconductor integrated circuit device may not be able to receive sufficient current. This in turn results in failed operation or malfunctioning of the semiconductor integrated circuit device. Further, if the number of the power supply terminals and/or ground terminals is insufficient, then some wiring from the power supply terminals (or the ground terminals) to the internal circuit becomes elongated. This in turn results in increased wire-resistances between the power supply terminals (or the ground terminals) and internal circuit. Consequently, the internal circuit encounters a large voltage drop, and the power supply voltage and/or ground voltage fluctuates. This causes malfunctioning of the semiconductor integrated circuit device. If the semiconductor integrated circuit device has to have the ESD prevention circuits in the cell areas of the power supply terminals or ground voltage terminals, but the number of the power supply terminals and/or ground voltage terminals is small, then the number of ESD prevention circuits that are connected to these terminals should correspondingly be small. This results in insufficient ESD resistance provided in the semiconductor integrated circuit device.
In view of these facts, the semiconductor integrated circuit devices are, in general, designed to have a large number of power supply terminals and ground voltage terminals as many as possible. For example, Japanese Patent Application Publication (Kokai) No. 6-252267 discloses the following arrangement. Power supply terminals for an internal circuit are provided around the internal circuit for supplying drive voltage to the internal circuit, ground terminals for the internal circuit are also provided around the internal circuit for supplying ground voltage to the internal circuit, another power supply terminals are provided around the internal circuit for supplying drive voltage to input/output circuits, and another ground voltage terminals are provided around the internal circuit for supplying ground voltage to the input/output circuits. The input/output circuits send and receive signals to and from external devices. Japanese Patent Application Kokai No. 2004-119712 teaches a similar terminal arrangement.
However, the increase of the terminals entails the increase of leads or pins. This results in the cost increase of the semiconductor integrated circuit device. Also this results in enlarged size of the semiconductor integrated circuit device. If the semiconductor integrated circuit device has a large size, it becomes difficult to use the semiconductor integrated circuit device in a small equipment or portable machine.
One object of the present invention is to provide a semiconductor integrated circuit device that can be made less expensive with small size, without degrading performances of the semiconductor integrated circuit device.
According to one aspect of the present invention, there is provided a semiconductor integrated circuit device that includes an internal circuit and at least one input/output circuit. Each input/output circuit is adapted to feed an input signal from outside to the internal circuit and to output an output signal from the internal circuit to the outside. The semiconductor integrated circuit device also includes at least one first power source terminal. Each first power source terminal is associated with each input/output circuit for supplying a drive voltage to the internal circuit. The semiconductor integrated circuit device also includes at lease one second power source terminal. Each second power source terminal is also associated with each input/output circuit for supplying a drive voltage to the associated input/output circuit. The semiconductor integrated circuit device also includes at least one common ground terminal. Each common ground terminal is also associated with each input/output circuit for supplying a common ground voltage to the internal circuit and the associated input/output circuit. The first power source terminal, second power source terminal and common ground terminal for each input/output circuit are arranged next to each other to define a unit terminal group.
In the semiconductor integrated circuit device, the ground terminal for the internal circuit also serves as the ground terminal for the input/output circuit. Therefore, it is possible to reduce wiring length between the terminals in the semiconductor integrated circuit device. This also reduces wiring length outside the semiconductor integrated circuit device. This contributes to size and cost reduction of the semiconductor integrated circuit device, without degrading performances of the semiconductor integrated circuit device.
For each unit terminal group, the first power source terminal may be connected to the internal circuit via a first power source cell. The first power source cell may include at least one of a first protective circuit and a first bypass capacitor. The second power source terminal may be connected to the associated input/output circuit via a second power source cell. The second power source cell may include at least one of a second protective circuit and a second bypass capacitor. The common ground terminal may be connected to the internal circuit and the associated input/output circuit via a common ground cell. The common ground cell may include at least one of a third protective circuit and a third bypass capacitor. The first power source cell, second power source cell and common ground cell for each input/output circuit may define a unit cell group such that the unit cell group is located next to the unit terminal group.
These and other objects, aspects and advantages of the present invention will become apparent to those skilled in the art when the following detailed description is read and understood in conjunction with the appended claims and drawings.
Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
A first embodiment of the present invention will be described with reference to
As shown in
The wiring 14, 15 and 16 surround the internal circuit 20, respectively, as shown in
The wiring 14, 15 and 16 lie on the cell formation areas 30, as best seen in
The terminals 13 are arranged on the upper face of the multilayer wiring 12 along the periphery of the semiconductor integrated circuit device 10. The terminals 13 have three roles and contain three groups for the three roles, respectively. Specifically, a first group of terminals are power supply terminals 13A associated to the internal circuit for feeding a drive voltage to the internal circuit 20, a second group of terminals are power supply terminals 13B associated to the input/output circuits for feeding a drive voltage to the input/output circuits 33 formed in the cell formation areas 30, and a third group of terminals are common ground terminals 13C to feed a common ground potential to the internal circuit 20 and input/output circuits 33. One terminal 13A, one terminal 13B and one terminal 13c are arranged next to each other and define in combination a unit terminal group 40, as shown in
As shown in
In this embodiment, a relatively low voltage (e.g., 1.5V) is applied to the power source terminal 13A for voltage feeding to the internal circuit 20 whereas a relatively high voltage (e.g., 3.3V) is applied to the power source terminal 13B for voltage feeding to the input/output circuit power source cell 22.
The cell formation area 30 has the input cell 31 to supply the input signal, which is given from the signal input terminal Tin, to the internal circuit 20. The cell formation area 30 also has the output cell 32 to supply the output signal (e.g., calculation results obtained from the internal circuit 20) to the signal output terminal Tout. The input cell 31 and output cell 32 constitute the input/output circuit 33. The input cell 31 is connected to the internal circuit 20 via the internal wiring 34, and the output cell 32 is connected to the internal circuit 20 via another internal wiring 35. The signal input terminal Tin and signal output terminal Tout are located above the cell formation area 30 and below the wiring 14 and 15 (or wiring 15 and 16). Signals are introduced to the internal circuit 20 from the signal input terminal Tin, and the calculation results of the internal circuit 20 (i.e., output signals) are supplied from the signal output terminal Tout.
The structures shown in
Referring now to
The common ground cell 23 is connected to the internal circuit power source cell 21 via the internal circuit 20 and to the input/output circuit power source cell 22 via the input/output circuit 33. Thus, drive currents to drive the internal circuit 20 and input/output circuit 33 flow to the common ground terminal 13C via the common ground cell 23, and further flow out of the semiconductor device 10 from the common ground terminal 13C.
As illustrated in
A process of making the semiconductor integrated circuit device 10 will now be described. First, semiconductor substrate 11 is prepared. Then, a plurality of semiconductor elements are formed in a predetermined region of the semiconductor substrate 11 by known techniques such as photolithography, ion implantation and film formation process (deposition process).
Subsequently, a multilayer wiring 12 is formed on the substrate 11 by known techniques such as photolithography and deposition process. Upon the provision of the multilayer wiring 12, the semiconductor elements are electrically connected to each other. Thus, the internal circuit 20, the power source cells 21, 22, the ground cells 23 and the input/output circuits 33 are provided. One power source cell 21, one power source cell 22 and one ground cell 23 are arranged next to each other in order to define one unit cell group 50.
The terminals 13 (13A, 13B and 13C), the wiring 14, 15 and 16, the signal input terminals Tin and the signal output terminals Tout are formed on the multilayer wiring 12 by known techniques such as photolithography and deposition process. One power source terminal 13A, one power source terminal 13B and one ground terminal 13C are arranged next to each other to define one unit terminal group 40. As shown in
Advantages of the semiconductor integrated circuit device 10 will be described. First, because the common ground terminal 13C is used as the ground terminal of the internal circuit 20 and also as the ground terminal of the input/output circuit power source cell 22, the number of ground terminals in the semiconductor integrated circuit device 10 is reduced. Thus, the semiconductor integrated circuit device 10 can be made compact.
Second, because each unit terminal group 40 includes the common ground terminal 13C and the power source terminal 13A or 13B is adjacent to the common ground terminal 13C, the path from the power source cell 21 (or 22) to the common ground cell 23 via the input/output circuit 33 (i.e., the escape route for ESD surging) is short. This improves the ESD resistance.
Third, the noise reduction is achieved efficiently. This will be explained with reference to
The pad 44 connected to the power source terminal 13A via the bonding wire 41 and lead 42 is coupled to the pad 44 connected to the common ground terminal 13C via the bonding wire 41 and lead 42 by the bypass capacitor C3. Likewise, the pad 44 connected to the power source terminal 13B via the bonding wire 41 and lead 42 is coupled to the pad 44 connected to the common ground terminal 13C via the bonding wire 41 and lead 42 by the bypass capacitor C4. The bypass capacitors C3 and C4 are provided to reduce or eliminate noises that would appear on the path from the power source terminal 13A to the common ground terminal 13C via the power source cell 21 and internal circuit 20, and on the path from the power source terminal 13B to the common ground terminal 13C via the power source cell 22 and input/output circuit 33.
In the illustrated embodiment, the terminals 13A to 13C are positioned next to each other (or adjacent to each other) to define a unit terminal group 40. Accordingly, when the bypass capacitors C3 and C4 are connected to the terminals 13A to 13C in the same unit terminal group 40, the wiring between the terminals 13A, 13B, 13C and the bypass capacitors C3, C4 can be made short. This reduces parasitic inductance between the terminals 13A, 13B, 13C and the bypass capacitors C3, C4, and efficiently achieves noise reduction.
In this embodiment, there are provided the bypass capacitors C1 and C2 in the common ground cell 23 for noise reduction, as shown in
The above-described advantages of the semiconductor integrated circuit device 10 are enhanced as the total number of the terminals 13 (13A to 13C) and signal input/output terminals in the circuit 10 becomes smaller. For example, the above-described advantages are obtained sufficiently when the total number of the terminals is less than one hundred, and the further enhanced advantages are obtained when the total number of the terminals is between thirty and sixty.
The positions of the three terminals 13A, 13B and 13C in each unit terminal group 40 are not limited to the illustrated ones. For example, the power source terminal 13A for the internal circuit may be positioned between the terminals 13B and 13C. In this arrangement, the power source cell 21 for the internal circuit is positioned at the center in the unit cell group 50. The arrangement of the terminals 13A, 13B and 13C in each of the unit terminal groups 40 may vary from one unit terminal group to another unit terminal group. For example, the power source terminal 13A may be at the center in one unit terminal group 40 but the power source terminal 13B may be at the center in another unit terminal group 40.
The second embodiment will be described with referent to
This arrangement has the following advantage. The path from the power source terminal 13A to the common ground cell 13C through the internal circuit 20 and the path from the power source terminal 13B to the common ground cell 13C through the power source cell 22 can be made shorter, if compared to the arrangement of Embodiment 1. This decreases the wiring resistance and increases the ESD resistance. The paths between the terminals 13A, 13B and 13C and the bypass capacitors C3 and C4, which are located outside the semiconductor integrated circuit device (see
In the first and second embodiments, all the terminals 13A, 13B and 13C have the same size. It should be noted, however, that the common ground terminal 13C may have a larger size than the other terminals 13A and 13B. This arrangement will be described with reference to
The semiconductor integrated circuit device 200 of the third embodiment has a plurality of unit terminal groups 40. Each terminal group 40 includes a power source terminal 13A for the internal circuit, a power source terminal 13B for the input/output circuit, and a common ground terminal 61. The width (or size) of the common ground terminal 61 is greater than that of the terminal 13A (or 13B). The common ground cell 62 for the common ground terminal 61 also has a greater width (or size) than the other cells 21 and 22, as shown in
When the width of the common ground terminal 61 has an enough width to support two bonding wires, then the common ground terminal 61 can have double bonding. Specifically, two bonding wires can be connected to a single lead. Therefore, the wiring resistance between the lead and mounting pads can be reduced. This also reduces an electric resistance at the common ground terminal 61, and contributes to reduction of wiring resistance of the common ground cell 62. As a result, the upper limit of current acceptable at the common ground cell 62 increases in a reliable manner.
The present invention is not limited to the described and illustrated embodiments. For example, the unit terminal group 40 of the first embodiment and the unit terminal group 40 of the second embodiment may be used together in the single circuit arrangement 10 of the first embodiment or in the single circuit arrangement 100 of the second embodiment. Likewise, the unit terminal group 40 of the first embodiment (or the second embodiment) and the unit terminal group 40 of the third embodiment may be used together in the single circuit arrangement 10 of the first embodiment or in the single circuit arrangement 200 of the third embodiment. Also, the unit terminal groups 40 of the first, second and third embodiments may be used together in any of the first, second and third embodiments.
This application is based on Japanese Patent Application No. 2010-81983 filed on Mar. 31, 2010, and the entire disclosure thereof is incorporated herein by reference.
Number | Date | Country | Kind |
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2010-081983 | Mar 2010 | JP | national |