A method and application for regulating the doping characteristics of two-dimensional materials through click chemistry reaction
Adsorbing maleimide to the two-dimensional transition metal sulfide surface through click chemical reactions solves the problems of doping instability and unreliability in the existing doping technology, achieving high stability doping, and reducing the contact resistance of the field effect transistor.
Patent Information
- Application Number
- CN202210492569.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-05-07
- Publication Date
- 2025-04-04
- Estimated Expiration
- 2042-05-07
AI Technical Summary
The existing two-dimensional transition metal sulfide doping technology has the problem of difficult to achieve heavy doping, unstable doping, unreliable and incompatible micro-nano processing processes, resulting in a large contact resistance of field effect transistors.
Maleimide is adsorbed to the surface of two-dimensional transition metal sulfide through click chemical reactions to form chemical bonds to achieve the regulation of the doping characteristics of two-dimensional materials. The method is carried out in a nitrogen environment and uses the soft nucleophilic properties of sulfur to pass through a carbon-sulfur bonded McKel addition reaction.
It achieves high stability doping, including thermal stability and chemical stability, is compatible with traditional micro-nano processing technology, is suitable for large-scale manufacturing technology, effectively reducing the contact resistance and Schottky barrier of field effect transistors.
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Figure CN114843403B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of novel semiconductor devices and relates to a method and application of regulating the doping characteristics of two-dimensional materials through click chemistry reactions. Background Art
[0002] As the core electronic components of modern integrated circuits, the continuous improvement of the performance of field effect transistors has driven the rapid development of the integrated circuit industry in the past half century. However, as the device size is miniaturized to its theoretical limit, the short channel effect causes the device performance of traditional silicon-based field effect transistors to degrade sharply. The traditional technical route of improving the performance of integrated circuits by reducing the device size and increasing the device integration density will face failure.
[0003] In order to meet the challenges of silicon-based integrated circuits, it has been proposed to use new semiconductor materials, such as two-dimensional materials, to reduce the impact of short channel effects and continue to promote the miniaturization of device size. There are many types of two-dimensional materials, and their structures are all stable single-layer materials in which atoms in the layer are combined by covalent bonds, while the atomic layers are combined by van der Waals forces to form a multi-layer stack. The surface of two-dimensional materials has no dangling bonds and has atomic-level flatness, which is conducive to the excellent electrical transport performance of field effect transistors with two-dimensional materials as channels, and reduces the impact of short channel effects on device performance.
[0004] Two-dimensional transition metal sulfides are currently relatively mature semiconductor two-dimensional materials, but there are still many challenges in regulating their doping properties:
[0005] (1) Two-dimensional transition metal sulfides have nanometer and sub-nanometer thicknesses, making it difficult to achieve heavy doping through ion implantation like silicon;
[0006] (2) The current doping method is mainly physical adsorption of small molecules, and there are few methods to achieve doping characteristics regulation through chemical reactions to form chemical bonds; however, physical adsorption has problems such as unstable doping, unreliability, and incompatibility with micro-nano processing technology;
[0007] (3) When using two-dimensional transition metal sulfides to prepare field-effect transistors, the use of traditional CMOS processes to deposit metal electrodes may destroy the lattice of the two-dimensional material, introduce interface states into the two-dimensional transition metal sulfides, and form a Fermi pinning effect, resulting in a large contact resistance of the field-effect transistor. The current doping characteristic control method has limited effect on solving this problem. Summary of the invention
[0008] The purpose of the present invention is to address the shortcomings of the existing two-dimensional transition metal sulfide doping technology and provide a method for regulating the doping characteristics of two-dimensional transition metal sulfide through click chemistry reaction. This method is used to heavily dope the source region and drain region of a two-dimensional transition metal sulfide field effect transistor to reduce the contact resistance of the field effect transistor.
[0009] The purpose of the present invention can be achieved by the following technical solutions:
[0010] According to the first aspect of the present specification, a method for regulating the doping characteristics of a two-dimensional material through a click chemistry reaction is provided, wherein the two-dimensional material is selected from a two-dimensional transition metal sulfide. The method adsorbs maleimide onto the surface of the two-dimensional transition metal sulfide through a click chemistry reaction to form a chemical bond. The charge transfer in the chemical bonding process leads to charge redistribution, thereby achieving regulation of the doping characteristics of the two-dimensional material.
[0011] Furthermore, the maleimide includes N-benzylmaleimide, N-methylmaleimide, N-phenylmaleimide, N-(4-bromophenyl)maleimide, and N-(4-aminophenyl)maleimide.
[0012] Furthermore, the soft nucleophilic property of sulfur is utilized to realize the click chemistry reaction through the Michael addition reaction of carbon-sulfur bonding, and the click chemistry reaction needs to be carried out in a nitrogen environment.
[0013] According to the second aspect of the present specification, a field effect transistor is provided, wherein the channel of the field effect transistor is a two-dimensional transition metal sulfide, the positions of the source region and the drain region are defined by a mask layer, and channel doping is performed in the source region and the drain region respectively by the method described in the first aspect.
[0014] Furthermore, the mask layer is photoresist or hexagonal boron nitride.
[0015] Furthermore, the gate dielectric layer of the field effect transistor may be silicon oxide, silicon nitride, or a material with a high dielectric constant, including aluminum oxide, hafnium oxide, zirconium oxide, and the like.
[0016] According to a third aspect of this specification, there is provided a method for preparing a field effect transistor as described in the second aspect, the method comprising:
[0017] (1) preparing a heavily doped silicon substrate with a gate dielectric layer;
[0018] (2) Transferring two-dimensional transition metal sulfides to the surface of a silicon substrate;
[0019] (3) defining the positions of the channel region, source region, and drain region through a mask layer;
[0020] (4) doping the two-dimensional transition metal sulfide in the source region and the drain region by a click chemical reaction between maleimide and the two-dimensional transition metal sulfide;
[0021] (5) Prepare source and drain electrodes.
[0022] Furthermore, the source and drain electrodes are prepared by photolithography, development, coating, and stripping processes, or by using a polymer-assisted transfer method.
[0023] The beneficial effects of the present invention are as follows: compared with the existing physical adsorption small molecule doping technology, the present invention adsorbs maleimide molecules on the surface of two-dimensional transition metal sulfide through a mild click chemistry reaction. Since the molecules form covalent bonds with the two-dimensional transition metal sulfide, the method exhibits high stability doping, including thermal stability and chemical stability, is compatible with traditional micro-nano processing technology, and is suitable for large-scale manufacturing technology; based on the two-dimensional transition metal sulfide field effect transistor, the method is used to heavily dope the two-dimensional transition metal sulfide in the source and drain regions of the transistor, which can effectively reduce the contact resistance and Schottky barrier; the method can reduce the damage of the metal deposition process to the two-dimensional transition metal sulfide lattice in the source and drain regions, thereby reducing the interface state introduced by the metal and reducing the adverse effects of the Fermi pinning effect. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 Prepare a flow chart for two-dimensional transition metal sulfide field-effect transistors;
[0025] Figure 2 Photoluminescence spectra of two-dimensional transition metal sulfide MoS2 before and after doping;
[0026] Figure 3 Schematic diagram of the structure of a two-dimensional transition metal sulfide field effect transistor;
[0027] Figure 4 The transfer characteristic curves of the source and drain regions of the two-dimensional transition metal sulfide MoS2 field effect transistor before and after doping. DETAILED DESCRIPTION
[0028] The following are specific embodiments of the present invention, which further illustrate the present invention. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application.
[0029] The present invention provides a method for regulating the doping characteristics of two-dimensional transition metal sulfide through click chemistry reaction. In this method, maleimide is adsorbed onto the surface of two-dimensional transition metal sulfide through click chemistry reaction to form chemical bonds. Charge transfer in the chemical bonding process leads to charge redistribution, thereby achieving regulation of the doping characteristics of the two-dimensional material.
[0030] Furthermore, the maleimide includes N-benzylmaleimide, N-methylmaleimide, N-phenylmaleimide, N-(4-bromophenyl)maleimide, and N-(4-aminophenyl)maleimide.
[0031] Furthermore, the soft nucleophilic property of sulfur is utilized to realize the click chemistry reaction through the Michael addition reaction of carbon-sulfur bonding, and the click chemistry reaction needs to be carried out in a nitrogen environment.
[0032] The present invention also provides a field effect transistor, wherein the channel of the field effect transistor is a two-dimensional transition metal sulfide, the positions of the source region and the drain region are defined by a mask layer, and channel doping is achieved in the source region and the drain region respectively by a click chemical reaction between maleimide and the two-dimensional transition metal sulfide.
[0033] Furthermore, a flat, wrinkle-free thin-layer two-dimensional transition metal sulfide nanosheet is selected as the channel material.
[0034] Furthermore, the mask layer is photoresist or hexagonal boron nitride.
[0035] Furthermore, the gate dielectric layer of the field effect transistor is a silicon oxide wafer, which can be replaced by a silicon nitride wafer. The thermal conductivity of silicon nitride is higher than that of silicon oxide, which can effectively reduce the transistor performance degradation caused by heat. The silicon oxide wafer can also be replaced by a silicon wafer with a high dielectric constant insulating layer grown on the surface. The high dielectric constant insulating layer includes aluminum oxide, hafnium oxide, zirconium oxide, etc., which can effectively reduce the adverse effects of charged impurities on the electrical transport of channel materials.
[0036] Furthermore, two-dimensional transition metal sulfides can be prepared by chemical vapor deposition, making the method suitable for large-scale production.
[0037] The present invention also provides a method for preparing a two-dimensional transition metal sulfide field effect transistor, such as Figure 1 As shown, the method includes:
[0038] (1) preparing a heavily doped silicon substrate with a gate dielectric layer;
[0039] (2) Transferring two-dimensional transition metal sulfides to the surface of a silicon substrate;
[0040] (3) defining the positions of the channel region, source region, and drain region through a mask layer;
[0041] (4) doping the two-dimensional transition metal sulfide in the source region and the drain region by a click chemical reaction between maleimide and the two-dimensional transition metal sulfide;
[0042] (5) Preparation of source and drain electrodes: The source and drain electrodes can be prepared by photolithography, development, coating, stripping, or polymer-assisted transfer.
[0043] Example 1
[0044] In this embodiment, the method for controlling the doping characteristics of two-dimensional transition metal sulfide by click chemistry reaction includes the following steps:
[0045] Place a silicon oxide wafer with a few layers of two-dimensional transition metal sulfide into a solution prepared by 20 ml of acetonitrile, 5 drops of triethylamine, and 100 mg of maleimide, and react in a nitrogen environment for 16 hours. Soak the silicon oxide wafer in acetonitrile to clean the maleimide physically adsorbed on the surface of the two-dimensional transition metal sulfide. The maleimide includes N-benzylmaleimide, N-methylmaleimide, N-phenylmaleimide, N-(4-bromophenyl)maleimide, and N-(4-aminophenyl)maleimide. The photoluminescence spectrum of the two-dimensional transition metal sulfide MoS2 changed before and after modification, as shown in Figure 2. Figure 2 As shown, it is proved that this method can realize the regulation of the doping properties of two-dimensional transition metal sulfides.
[0046] Example 2
[0047] In this embodiment, the structure of the two-dimensional transition metal sulfide field effect transistor is as follows: Figure 3 As shown, the substrate is an oxide silicon wafer, the thickness of the surface oxide silicon layer is 285nm, and the single crystal silicon is p-type heavily doped silicon with a resistivity of 0.001-0.005Ω·cm. Above the oxide silicon is a two-dimensional transition metal sulfide. The two-dimensional transition metal sulfide is divided into a channel region, a source region, and a drain region. Above the two-dimensional transition metal sulfide channel region is hexagonal boron nitride, and the two-dimensional transition metal sulfide source region and drain region use the method described in Example 1 to perform a click chemistry reaction, that is, a covalent bond is formed with maleimide on the surface of the two-dimensional transition metal sulfide. Above the two-dimensional transition metal sulfide source region and drain region is a metal electrode.
[0048] Example 3
[0049] The specific device preparation process in this embodiment includes the following steps:
[0050] (1) Metal marks are prepared on silicon oxide wafers through processes such as photolithography and sputtering for alignment in subsequent overlay processes.
[0051] (2) Preparation of few-layer two-dimensional transition metal sulfides: A thin layer of two-dimensional transition metal sulfide is transferred to a silicon oxide wafer with a metal marker by mechanical exfoliation, and the target few-layer two-dimensional transition metal sulfide is found on the silicon oxide wafer using a microscope. Transition metal sulfides include MoS2, WS2, PtS2, etc.
[0052] (3) Cut a small piece of PMDS and stick it on a glass slide. Use PDMS to stick hexagonal boron nitride (BN) crystals. Find hexagonal boron nitride nanosheets of appropriate size under a microscope. Use a transfer platform to transfer the hexagonal boron nitride above the two-dimensional transition metal sulfide channel area, so that the source and drain areas are exposed.
[0053] (4) Using the method described in Example 1, a click chemistry reaction is performed on the two-dimensional transition metal sulfide in the source region and the drain region (the region not covered by hexagonal boron nitride) to achieve doping characteristic regulation.
[0054] (5) Spin-coating photoresist on a silicon oxide wafer with transition metal sulfides, performing ultraviolet exposure using a laser direct writing device, and developing the complete patterning process in a developer; then using a metal coating device to make a gold electrode, and completing the preparation of metal electrodes for the source and drain regions of the field effect transistor through a metal stripping process.
[0055] (6) The two-dimensional transition metal sulfide effect transistor is annealed in a hydrogen-argon mixed gas atmosphere (hydrogen content is 10%) and the annealing temperature is 200°C. The original device and the source and drain doped device are compared and tested. The electrical properties are as follows: Figure 4 As shown in the figure, it can be seen from the transfer curve that the threshold voltage of the device doped with the source and drain regions is reduced and the on-state current is increased, which proves that the contact resistance is reduced.
[0056] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.
Claims
1. A field effect transistor, characterized in that: The channel of the field effect transistor is a two-dimensional transition metal sulfide. The positions of the source region and the drain region are defined by a mask layer, and the doping of the two-dimensional transition metal sulfide is achieved in the source region and the drain region through a click chemical reaction between maleimide and the two-dimensional transition metal sulfide.
2. The field effect transistor according to claim 1, characterized in that Maleimide is adsorbed onto the surface of two-dimensional transition metal sulfide through click chemistry reaction to form chemical bonds. The charge transfer in the chemical bonding process leads to charge redistribution, thereby achieving the regulation of the doping properties of two-dimensional transition metal sulfide.
3. The field effect transistor according to claim 1, characterized in that The maleimide includes N-benzylmaleimide, N-methylmaleimide, N-phenylmaleimide, N-(4-bromophenyl)maleimide, and N-(4-aminophenyl)maleimide.
4. The field effect transistor according to claim 1, characterized in that The soft nucleophilic property of sulfur is utilized to realize the click chemistry reaction through the Michael addition reaction of carbon-sulfur bonding, and the click chemistry reaction needs to be carried out in a nitrogen environment.
5. The field effect transistor according to claim 1, characterized in that: The mask layer is photoresist or hexagonal boron nitride.
6. The field effect transistor according to claim 1, characterized in that The gate dielectric layer of the field effect transistor is silicon oxide, silicon nitride, or a material with a high dielectric constant, including aluminum oxide, hafnium oxide, and zirconium oxide.
7. A method for preparing a field effect transistor according to any one of claims 1 to 6, characterized in that: The method includes: (1) preparing a heavily doped silicon substrate with a gate dielectric layer; (2) Transferring two-dimensional transition metal sulfides to the surface of a silicon substrate; (3) defining the positions of the channel region, source region, and drain region through a mask layer; (4) doping the two-dimensional transition metal sulfide in the source region and the drain region by a click chemical reaction between maleimide and the two-dimensional transition metal sulfide; (5) Prepare source and drain electrodes.
8. The preparation method according to claim 7, characterized in that: The source region and drain region electrodes are prepared by photolithography, development, coating, and stripping processes, or by using a polymer-assisted transfer method.