Patent Grant
9991082
The present invention is related to a semiconductor device and a method for manufacturing the semiconductor device.
Semiconductor devices, such as vacuum field effect transistors (VFTs), may be used in place of vacuum tubes in various applications, such as one or more of stereo systems, microwave ovens, satellites, etc.
As an example, a vacuum field effect transistor (VFT) may include a source electrode, a drain electrode, a vacuum channel positioned between the source and the drain electrode, a gate electrode positioned under the source electrode and the drain electrode, an insulator that insulates the gate electrode from the source electrode and the drain electrode, and a substrate for supporting at least the gate electrode and the insulator. As another example, a VFT may include a source electrode that has a hollow structure, a gate electrode positioned under the source electrode, a first insulator that insulates the gate electrode from the source electrode, a second insulator disposed on the source electrode and surrounding a vacuum channel, a drain electrode positioned above the vacuum channel, and a substrate that supports at least the gate electrode and the first insulator.
In operating a VFT, a suitable bias may be applied to the gate electrode and/or to a position between the source electrode and the drain electrode to enable electrons to be transmitted from the source electrode through the vacuum channel to the drain electrode. In general, the distribution of the electric field in the vacuum channel may be substantially asymmetric. As a result, transmission of electrons may not be sufficiently controlled, such that the on and off of the VFT may not be effectively and timely controlled. For achieving desirable control of the VFT, additional voltage may be required, such that the operation of the VFT may require substantially high energy consumption.
An embodiment of the present invention may be related to a semiconductor device that may include the following elements: a semiconductor substrate, an insulator positioned on the substrate, a source electrode positioned on the insulator, a drain electrode positioned on the insulator, a gate electrode positioned between the source electrode and the drain electrode, a hollow channel surrounded by the gate electrode and positioned between the source electrode and the drain electrode, a dielectric member positioned between the hollow channel and the gate electrode, a first insulating member positioned between the gate electrode and the source electrode; and a second insulating member positioned between the gate electrode and the drain electrode.
The semiconductor device may include a first sidewall and a second sidewall. A portion of the first sidewall may be positioned between the first insulating member and the source electrode. A portion of the second sidewall may be positioned between the second insulating member and the drain electrode.
At least one of the first sidewall and the second sidewall may be formed of a low work function material.
The low work function material may be or may include at least one of Zr, V, Nb, Ta, Cr, Mo, W, Fe, Co, Pd, Cu, Al, Ga, In, Ti, TiN, TaN, and diamond.
At least one of the first sidewall and the second sidewall may have a curved surface that is convex toward and/or disposed inside the hollow channel.
At least one of the gate electrode, the source electrode, and the drain electrode may be formed of at least one of Cr, W, Co, Pd, Cu, Al, Ti, TiN, Ta, TaN, Au, Ag, and Pt.
The hollow channel may contain an inert gas or a substantially vacuum space.
The hollow channel may have at least one of a circular cylindrical structure, an oval cylindrical structure, a circular frustum structure, an oval frustum structure, a circular cone structure.
A thickness of the dielectric member may be in a range of 1 nm to 10 nm.
An embodiment of the present invention may be related to a method for manufacturing a semiconductor device. The method may include the following steps: preparing a substrate structure that includes a semiconductor substrate and an insulating layer; forming a sacrificial layer on the insulating layer; using the sacrificial layer to form a wire (e.g., a nanowire); forming a dielectric member that surrounds the wire; forming a gate electrode that surrounds the dielectric member; removing the wire for forming a hollow channel that is surrounded by the gate electrode; forming a first insulating member and a second insulating member; forming a source electrode such that the first insulating member is positioned between the gate electrode and the source electrode; and forming a drain electrode such that the second insulating member is positioned between the gate electrode and the drain electrode.
The method may include the following steps: removing two portions of a dielectric layer that are located at two ends of the gate electrode for forming the dielectric member; and removing two portions of the sacrificial layer that are located at the two ends of the gate electrode for forming the wire.
The method may include the following steps: forming a first sidewall at the first insulating member before the step of forming the source electrode; and forming a second sidewall at the second insulating member before the step of forming the drain electrode. A portion of the first sidewall may be positioned between the first insulating member and the source electrode after the step of forming the source electrode. A portion of the second sidewall may be positioned between the second insulating member and the drain electrode after the step of forming the drain electrode
At least one of the first sidewall and the second sidewall may be formed of a low work function material.
At least one of the first sidewall and the second sidewall may include a curved surface that is convex toward the hollow channel.
The method may include performing annealing using an atmosphere that includes at least one of H2 and N2 such that at least one of the first sidewall and the second sidewall may include a curved surface that is convex toward and/or positioned inside the hollow channel. The annealing may be performed at a temperature that is in a range of 600° C. to 1300° C.
The method may include providing an inert gas in the hollow channel and/or evacuating the hollow channel.
The hollow channel may have at least one of a circular cylindrical structure, an oval cylindrical structure, a circular frustum structure, an oval frustum structure, a circular cone structure.
The method may include the following steps: patterning the sacrificial layer and the insulating layer to form a fin structure that includes a portion of the sacrificial layer and a portion of the insulating layer, wherein the portion of the insulating layer may directly contact the portion of the sacrificial layer; removing the portion of the insulating layer; and performing annealing on the portion of the sacrificial layer to form the wire. The portion of the sacrificial layer may have a substantially rectangular cross-section. The wire may have a substantially circular or oval cross-section. The annealing may be performed using an atmosphere that includes at least one of He, N2, Ar, and H2.
The step of removing the portion of the insulating layer may include etching the portion of the insulating layer using at least one of a buffered oxide etch solution and a diluted hydrofluoric acid solution.
The sacrificial layer may be formed of at least one of Al, polycrystalline silicon, Cr, Mo, W, Fe, Co, Cu, Ga, In, and Ti.
A thickness of the dielectric member may be in a range of 1 nm to 10 nm.
According to embodiments of the present invention, an electric field between the source electrode and the drain electrode may be substantially surrounded and/or enclosed by the gate electrode. Therefore, the on and off of an electron flow between the source electrode and the drain electrode may be substantially effectively controlled, and energy may be efficiently utilized. Advantageously, controllability of the semiconductor device may be satisfactory, and energy consumption of the semiconductor device may be minimized.
The above summary is related to one or more of many embodiments of the invention disclosed herein and is not intended to limit the scope of the invention.
Example embodiments of the present invention are described with reference to the accompanying drawings. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Embodiments of the present invention may be practiced without some or all of these specific details. Well known process steps and/or structures may not have been described in detail in order to not unnecessarily obscure the present invention.
The drawings and description are illustrative and not restrictive. Like reference numerals may designate like (e.g., analogous or identical) elements in the specification. Repetition of description may be avoided.
The relative sizes and thicknesses of elements shown in the drawings are for facilitate description and understanding, without limiting the present invention. In the drawings, the thicknesses of some layers, films, panels, regions, etc., may be exaggerated for clarity.
Illustrations of example embodiments in the figures may represent idealized illustrations. Variations from the shapes illustrated in the illustrations, as a result of, for example, manufacturing techniques and/or tolerances, may be possible. Thus, the example embodiments should not be construed as limited to the shapes or regions illustrated herein but are to include deviations in the shapes. For example, an etched region illustrated as a rectangle may have rounded or curved features. The shapes and regions illustrated in the figures are illustrative and should not limit the scope of the example embodiments.
Although the terms “first”, “second”, etc. may be used herein to describe various elements, these elements, should not be limited by these terms. These terms may be used to distinguish one element from another element. Thus, a first element discussed below may be termed a second element without departing from the teachings of the present invention. The description of an element as a “first” element may not require or imply the presence of a second element or other elements. The terms “first”, “second”, etc. may also be used herein to differentiate different categories or sets of elements. For conciseness, the terms “first”, “second”, etc. may represent “first-category (or first-set)”, “second-category (or second-set)”, etc., respectively.
If a first element (such as a layer, film, region, or substrate) is referred to as being “on”, “neighboring”, “connected to”, or “coupled with” a second element, then the first element can be directly on, directly neighboring, directly connected to, or directly coupled with the second element, or an intervening element may also be present between the first element and the second element. If a first element is referred to as being “directly on”, “directly neighboring”, “directly connected to”, or “directed coupled with” a second element, then no intended intervening element (except environmental elements such as air) may also be present between the first element and the second element.
Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper”, and the like, may be used herein for ease of description to describe one element or feature's spatial relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms may encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments and is not intended to limit the invention. As used herein, the singular forms, “a”, “an”, and “the” may indicate plural forms as well, unless the context clearly indicates otherwise. The terms “includes” and/or “including”, when used in this specification, may specify the presence of stated features, integers, steps, operations, elements, and/or components, but may not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meanings as commonly understood by one of ordinary skill in the art related to this invention. Terms, such as those defined in commonly used dictionaries, should be interpreted as having meanings that are consistent with their meanings in the context of the relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The term “connect” may mean “electrically connect”. The term “conduct” may mean “electrically conduct”. The term “insulate” may mean “electrically insulate”.
Unless explicitly described to the contrary, the word “comprise” and variations such as “comprises”, “comprising”, “include”, or “including” may imply the inclusion of stated elements but not the exclusion of other elements.
Various embodiments, including methods and techniques, are described in this disclosure. Embodiments of the invention may also cover an article of manufacture that includes a non-transitory computer readable medium on which computer-readable instructions for carrying out embodiments of the inventive technique are stored. The computer readable medium may include, for example, semiconductor, magnetic, opto-magnetic, optical, or other forms of computer readable medium for storing computer readable code. Further, the invention may also cover apparatuses for practicing embodiments of the invention. Such apparatus may include circuits, dedicated and/or programmable, to carry out operations pertaining to embodiments of the invention. Examples of such apparatus include a general purpose computer and/or a dedicated computing device when appropriately programmed and may include a combination of a computer/computing device and dedicated/programmable hardware circuits (such as electrical, mechanical, and/or optical circuits) adapted for the various operations pertaining to embodiments of the invention.
As illustrated in
In the semiconductor device, a portion of the gate 1106 may be positioned between two portions of the insulator 802. A portion of the gate 1106 may be positioned the first insulating member 1401 and the second insulating member 1402. The dielectric member 1105 may substantially completely surround the hollow channel 1307 and may be substantially completely surrounded by the gate 1106. If the element 1602 is a source electrode, then the element 1601 may be a drain electrode.
An operation of the semiconductor device may include one or more of the following steps: applying a negative voltage to the source 1601 to generate escaping electrons that may enter the hollow channel 1307, applying a positive voltage to the drain 1602 to form an electric field between the source 1601 and the drain 1602 for enabling the electrons to travel from the source 1601 toward the drain 1602, and applying a positive voltage to the gate 1106. If the positive voltage applied to the gate 1106 is less than a threshold voltage, the electrons may need to tunnel through a barrier that has a substantially large width in order to enter the hollow channel 1307 and/or to reach the drain 1602; as a result, the electrons may not be able travel from the source 1601 to the drain 1602, such that the semiconductor device may function as an insulator and/or may be in an “off” state. If the positive voltage applied to the gate 1106 is greater than the threshold voltage, the electrons may tunnel through a barrier that has a substantially small width, may enter the hollow channel 1307, and may reach the drain 1602; as a result, the electrons may able travel from the source 1601 to the drain 1602, such that the semiconductor device may function as a conductor and/or may be in an “on” state. The threshold value may be obtained through experiments and/or tests.
In embodiments, the electric field between the source 1601 and the drain 1602 may be substantially surrounded and/or enclosed by the gate 1106. Therefore, the on and off of the electron flow may be substantially effectively controlled, and energy may be efficiently utilized. Advantageously, controllability of the semiconductor device may be satisfactory, and energy consumption of the semiconductor device may be minimized.
In an embodiment, one or more inert gases may be provided in the hollow channel 1307. For example, helium (He) may be provided in the hollow channel 1307.
In an embodiment, the hollow channel 1307 may contain a substantially vacuum space. The substantially vacuum space in the hollow channel 1307 may facilitate transmission of electrons. The substantially vacuum space in the hollow channel 1307 may be implemented by placing the hollow channel 1307 or a semiconductor device structure with the hollow channel 1307 in a sealed chamber and then extracting air and/or gases from the hollow channel 1307 using one or more of a molecular pump, a mechanical pump, etc.
In an embodiment, the pressure inside the hollow channel 1307 may be in a range of 0.001 torr to 50 torr. This range may be consistent with a related physical vapor deposition (PVD) process pressure setting.
A conventional tube may require maintaining a substantially low pressure (i.e., substantial vacuum), for preventing collision between electrons and gas molecules inside the tube. In a conventional tube, an electric field may cause positive ions generated from the residual gas to accelerate and bombard the cathode, such that damage may be incurred.
In an embodiment of the invention, dimensions of a vacuum transistor may be substantially smaller than the mean free path of electrons, and the working voltage may be sufficiently low, such that generation of unwanted positive ions may be prevented, and such that the vacuum transistor may be functional and durable at an atmospheric pressure.
In an embodiment, the pressure inside the hollow channel may be substantially equal to an atmospheric pressure.
The hollow channel 1307 may have one or more of a circular cylindrical structure, an oval cylindrical structure, a circular frustum structure, an oval frustum structure, a circular cone structure, etc. Cross-sections of the hollow channel 1307 viewed in an extension direction of the hollow channel 1307 (and/or in a source-to-drain electron transmission direction) may have one or more of a circular shape, an oval shape, etc., and may have one or more sizes.
The distance between the source 1601 and the drain 1602 may be in a range of several nanometers to several hundred nanometers. The distance may be less than 10 nm. The distance may be less than a mean free path of electrons in the air. The smaller the distance, the lower the chance of unwanted collision. At the same time, a sufficient distance may be configured for feasible and robust processing of the semiconductor device structure. The electron mean free path may be related to a voltage between the source 1601 and the drain 1602 and/or may be related to a pressure inside the hollow channel 1307. In an embodiment, the electron mean free path may be in the order of 1 cm.
The thickness of the dielectric member 105 may be in a range of 1 nm to 10 nm. The dielectric member 105 is sufficient thin such that desirable control may be achieved with a low supply voltage. At the same time, a sufficient thickness of the dielectric member 105 may be configured for feasible and robust processing of the semiconductor device structure.
The semiconductor device illustrated in
The semiconductor device illustrated in
At least one of the first sidewall 1501 and the second sidewall 1502 may be made of a low work function material, which may facilitate transmission and reception of electrons. The work function of the low work function material may be less than 6 eV. The low work function material may include at least one of Zr (zirconium), V (vanadium), Nb (niobium), Ta (tantalum), Cr (chromium), Mo (molybdenum), W (tungsten), Fe (iron), Co (cobalt), Pd (palladium), Cu (copper), Al (aluminum), Ga (gallium), In (indium), Ti (titanium), TiN (titanium nitride), TaN (tantalum nitride), diamond, etc.
At least one of the first sidewall 1501 and the second sidewall 1502 may have a curved surface (e.g., an arcuate surface) that may be convex toward the hollow channel 1307 and/or positioned inside the hollow channel 1307. The curved surface may minimize potential acute angle effects to prevent the source 1611 from being burned. The curved surface(s) may provide a substantially large electron transmission area and/or a substantially large electron reception area, such that the effectiveness and/or efficiency of the semiconductor device may be maximized.
One or more of the source 1601, the source 1611, the drain 1602, the drain 1612, and the gate 1106 may be made of at least one of Cr, W, Co, Pd, Cu, Al, Ti, TiN, Ta, TaN, Au (gold), Ag (silver), Pt (platinum), etc.
A thickness of the sacrificial layer 603 may be in a range of several nanometers to several tens of nanometers. According particular embodiments, a thickness of the sacrificial layer 603 may be less than or greater than this range.
The on, the sacrificial layer 603 may be made of and/or may include at least one of the following materials: Al, polycrystalline silicon), Cr, Mo, W, Fe, Co, Cu, Ga, In, Ti, etc.
Referring to
Referring to
The fin structure may include a first portion of the sacrificial member 703 and a first portion of the insulating material member 702. The first portion of the sacrificial member 703 may be positioned between two other portions of the sacrificial member 703 in the extension direction of the fin structure. The first portion of the insulating material member 702 may directly contact the first portion of the sacrificial member 703 and may be positioned between the first portion of the sacrificial member 703 and a second portion of the insulating material member 702. The second portion of the insulating material member 702 may be wider than the first second portion of the insulating material member 702 and may be positioned between the first second portion of the insulating material member 702 and the semiconductor substrate 601.
Referring to
The first portion of the insulating material member 702 may be removed and/or the nanowire bridge beam 804 may be formed through one or more of a selective isotropic etching process, a selective lateral etching process, etc. using one or more etching solutions, such as one or more of BOE (buffered oxide etch solution), DHF (diluted hydrofluoric acid solution), etc.
Referring to
Referring to
In an embodiment, the dielectric material member 1005 may include and/or may be at least one of an oxide member (e.g., an Al2O3 member) and a nitride member (e.g., an AlN member) formed through applying plasma to the sacrificial unit 903. The plasma may include ions or one or more of O2 (oxygen), N2O (nitrous oxide), and NH3 (ammonia).
In an embodiment, the dielectric material member 1005 may include and/or may be at least one dielectric material (e.g., at least one of Al2O3, AlN, SiO2, etc.) deposited on surfaces of the sacrificial unit 903 through at least one deposition method, such as ALD.
A thickness of the dielectric material member 1005 may be in a range of 1 nm to 10 nm. According to embodiments, a thickness of the dielectric material member 1005 may be less than 1 nm or greater than 10 nm.
Referring to
Referring to
The two end portions of the dielectric material member 1105 and/or the two end portions of the sacrificial unit 903 may be removed through one or more of photolithography, etching, etc.
The nanowire 904 may be removed through selective wet etching and/or one or more other material processes.
The hollow channel 1307 may contain one or more inert gases (e.g., He) or may contain a substantially vacuum space. The substantially vacuum space in the hollow channel 1307 may facilitate transmission of electrons. The substantially vacuum space in the hollow channel 1307 may be implemented by placing the hollow channel 1307 or a semiconductor device structure with the hollow channel 1307 in a sealed chamber and then extracting air and/or gases from the hollow channel 1307 using one or more of a molecular pump, a mechanical pump, etc.
The hollow channel 1307 may have one or more of a circular cylindrical structure, an oval cylindrical structure, a circular frustum structure, an oval frustum structure, a circular cone structure, etc. Cross-sections of the hollow channel 1307 viewed in an extension direction of the hollow channel 1307 may have one or more of a circular shape, an oval shape, etc., and may have one or more sizes.
Referring to
In an embodiment, each of the first insulating member 1401 and the second insulating member 1402 may include and/or may be at least one of an oxide member (e.g., an Al2O3 member) and a nitride member (e.g., an AlN member) formed through applying plasma to the gate 1106. The plasma may include ions or one or more of O2 (oxygen), N2O (nitrous oxide), and NH3 (ammonia).
In an embodiment, each of the first insulating member 1401 and the second insulating member 1402 may include and/or may be at least one dielectric material (e.g., at least one of Al2O3, AlN, SiO2, etc.) deposited on the gate 1106 through at least one deposition method, such as ALD.
Referring to
The source 1601 and/or the drain 1602 may be formed of at least one of the following conductive materials: Cr, W, Co, Pd, Cu, Al, Ti, TiN, Ta, TaN, Au, Ag, Pt, etc. The source 1601 and/or the drain 1602 may be formed through one or more of the following steps: depositing at least one suitable conductive material on the portion of the dielectric material member 1005 using at least one deposition method, such as at least one of CVD, MOCVD, and ALD; and pattering the deposited conductive material using at least one patterning method, such as one or more of photolithography, dry etching, and lift-off. In an embodiment, the source 1601 and/or the drain 1602 may be formed through both photolithography and dry etching. In an embodiment, the source 1601 and/or the drain 1602 may be formed through a lift-off process that does not involve photolithography or dry etching.
Referring to
At least one of the first sidewall 1501 and the second sidewall 1502 may be made of a low work function material, which may facilitate transmission and reception of electrons. The work function of the low work function material may be less than 6 eV. The low work function material may include at least one of Zr, V, Nb, Ta, Cr, Mo, W, Fe, Co, Pd, Cu, Al, Ga, In, Ti, TiN, TaN, diamond, etc.
The sidewalls 1501 and 1502 may be formed through one or more of the following steps: depositing at least one suitable low work function material on the insulator 802 using at least one deposition process, such as at least one of PVD, CVD, etc.; and performing an anisotropic etching on the deposited low work function material to form the sidewalls 1501 and 1502.
Referring to
In an embodiment, an annealing process may be performed on the first sidewall 1501 and the second sidewall 1502 (and/or a structure that includes the sidewalls), such that each of the first sidewall 1501 and the second sidewall 1502 may have a curved surface (e.g., an arcuate surface) that may be convex toward the hollow channel 1307. The curved surface may minimize potential acute angle effects to prevent the source 1611 from being burned. The curved surface(s) may provide a substantially large electron transmission area and/or a substantially large electron reception area, such that the effectiveness and/or efficiency of the semiconductor device may be advantageously maximized. The annealing may be performed in an environment (or atmosphere) of one or more of N2, H2, etc. The annealing may be performed in a temperature in a range of 600° C. to 1300° C. and/or performed about/at the melting point of the low work function material (which may be in the range of 600° C. to 1300° C.). In particular embodiments, the annealing temperature may be higher or lower than this range.
While this invention has been described in terms of several embodiments, there are alterations, permutations, and equivalents, which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present invention. Furthermore, embodiments of the present invention may find utility in other applications. The abstract section is provided herein for convenience and, due to word count limitation, is accordingly written for reading convenience and should not be employed to limit the scope of the claims. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014 1 0129139 | Apr 2014 | CN | national |
This application is a divisional application of U.S. patent application Ser. No. 14/558,050, filed on Dec. 2, 2014 and claims priority to Chinese Patent Application No. 201410129139.6, filed on Apr. 1, 2014, the disclosures of which are incorporated herein by their reference.
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| Number | Date | Country | |
|---|---|---|---|
| 20170294284 A1 | Oct 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14558050 | Dec 2014 | US |
| Child | 15631113 | US |
