Method for long-distance epitaxial growth of nitride film

Abstract

The invention discloses a method for remote epitaxial growth of a nitride film, which comprises the following steps: argon etching and annealing treatment are sequentially carried out on a silicon substrate, the argon etching is used for removing an oxide layer on the surface of the silicon substrate, and the annealing treatment is used for repairing surface crystal lattices of the silicon substrate; the silicon substrate is a monocrystalline silicon substrate with a (100) surface; carrying out surface nitriding treatment on the silicon substrate so as to form a Si3N4 layer on the surface of the silicon substrate; a single-layer graphene layer is formed on the surface of the side, provided with the Si3N4 layer, of the silicon substrate; the surface of the Si3N4 layer has potential fluctuation and is used for inducing redistribution of charges on the surface of the single-layer graphene layer; and performing remote epitaxial growth of a nitride film on the single-layer graphene layer. By means of the technical scheme, the nitride film can be grown on the silicon substrate in a remote epitaxial mode.

Description

[0001] This application is a divisional application of the invention patent application with the application date of February 24, 2025, application number 2025101997716, and invention name “Method for remote epitaxial growth of nitride film on silicon substrate, nitride film and semiconductor device”. Technical Field

[0002] The present invention relates to the technical field of remote epitaxy and third-generation semiconductor materials, and in particular to a method for remote epitaxial growth of a nitride film on a silicon substrate. Background Art

[0003] In recent years, heterogeneous integration of two-dimensional (2D) materials, particularly graphene and nitrides, has shown promising applications in the fabrication of flexible wearable devices and portable electronic and photonic devices. Recently, a new epitaxial growth technique, remote epitaxy, exploits graphene's lattice transparency to generate remote electrostatic interactions between the substrate and the epitaxial layer. This interaction allows the epitaxial layer to "copy" the substrate's lattice information through the graphene, thereby ensuring lattice orientation consistency. This approach not only mitigates the lattice mismatch introduced by the substrate, but also graphene's excellent thermal conductivity mitigates the thermal mismatch between the epitaxial layer and the substrate, enabling the fabrication of high-quality single-crystalline nitride films. However, the silicon substrate itself lacks spontaneous polarization and exhibits minimal surface potential fluctuations. This prevents the silicon substrate's surface potential from penetrating the 2D material, preventing charge redistribution on the 2D material's surface and, consequently, preventing the growth of nitride epitaxial layers with the same lattice information as the substrate. Furthermore, the large lattice mismatch also makes it difficult to grow high-quality nitride films. Summary of the Invention

[0004] In view of this, one of the objects of the present invention is to provide a method for remote epitaxial growth of nitride films on silicon substrates, by means of surface nitridation treatment, so that silicon substrates that cannot be remotely epitaxially grown can be remotely epitaxially grown, thereby remotely epitaxially growing nitride films.

[0005] A method for remote epitaxial growth of a nitride film on a silicon substrate comprises the following steps:

[0006] Performing a surface nitriding treatment on a silicon substrate to form a Si3N4 layer on the surface of the silicon substrate;

[0007] forming a single-layer graphene layer on a surface of the silicon substrate having the Si3N4 layer;

[0008] remote epitaxially growing a nitride film on the single-layer graphene layer;

[0009] The lattice information of the nitride film is the same as the lattice structure information of the Si3N4 layer.

[0010] Preferably, the crystal structure of the nitride film and the Si3N4 layer are both hexagonal, more preferably hexagonal wurtzite structure.

[0011] According to some preferred implementation aspects of the present invention, the surface nitriding treatment comprises the following steps:

[0012] The silicon substrate is placed in a MBE (Molecular Beam Epitaxy) vacuum chamber, the temperature is set to 420-550° C., and nitrogen gas with a flow rate of 0.9-1.8 sccm is introduced into the MBE vacuum chamber; wherein the duration of the nitrogen gas injection is 4-7 minutes;

[0013] Treating the silicon substrate with nitrogen-containing plasma at a power of 220-370 W for 10-24 min;

[0014] After the temperature in the vacuum chamber drops to room temperature, the nitrided silicon substrate is removed; the nitrided silicon substrate has a Si3N4 layer on at least one surface. Currently available surface nitridation processes are only used to remove surface impurities or adsorbed oxygen and water molecules, and to repair lattice defects such as nitrogen vacancies. The surface treatment process of the present invention, however, utilizes higher processing power and takes longer, and is intended to form a Si3N4 layer on at least one surface of the silicon substrate.

[0015] According to some preferred implementation aspects of the present invention, the material of the nitride film is gallium nitride, and the remote epitaxial growth of the nitride film includes the following steps:

[0016] At a temperature of 600-800°C, a nitrogen source with a flow rate of 8000-14000 sccm, a gallium source with a flow rate of 30-80 sccm, and a carrier gas are introduced for 5-30 minutes to grow a nucleation layer;

[0017] Under the condition of a temperature of 1000-1200° C., introducing a nitrogen source with a flow rate of 5000-8000 sccm, a gallium source with a flow rate of 30-90 sccm, and a carrier gas, and reacting for 150-200 minutes to grow a thin film layer on the nucleation layer to obtain the nitride thin film;

[0018] The carrier gas includes nitrogen with a flow rate of 400 sccm-600 sccm and hydrogen with a flow rate of 40 sccm-60 sccm.

[0019] According to some preferred implementation aspects of the present invention, the material of the nitride film is aluminum nitride, and the remote epitaxial growth of the nitride film includes the following steps:

[0020] The nucleation layer is grown by introducing a nitrogen source with a flow rate of 8000-14000sccm, an aluminum source with a flow rate of 30-80sccm and a carrier gas at a temperature of 800-1100℃ for 5-30min;

[0021] The thin film layer is grown on the nucleation layer by introducing a nitrogen source with a flow rate of 5000-8000sccm, an aluminum source with a flow rate of 30-90sccm and a carrier gas at a temperature of 1200-1400℃ for 150-200min, so as to obtain the nitride thin film.

[0022] The carrier gas comprises nitrogen with a flow rate of 400sccm-600sccm and hydrogen with a flow rate of 40sccm-60sccm.

[0023] According to some preferred embodiments of the present application, the silicon substrate is a (100) plane monocrystalline silicon substrate.

[0024] Before the surface nitriding treatment of the silicon substrate, the following steps are included:

[0025] The silicon substrate is subjected to surface cleaning.

[0026] The cleaned silicon substrate is placed in an MBE vacuum chamber, argon is introduced into the MBE vacuum chamber, the argon is used to etch the oxide layer on the surface of the cleaned silicon substrate, after the argon etching is completed, the temperature is increased and annealing is performed to repair the surface lattice. That is, the argon etching is performed in the MBE vacuum chamber, the oxide layer on the surface of the cleaned silicon substrate is etched, and then annealing is performed to smooth the surface and repair the lattice, so that the surface flatness of the silicon substrate is further improved.

[0027] According to some preferred embodiments of the present application, the process conditions of the argon etching include a pressure of 4.5-5.5×10 6 torr, a temperature of 380-420℃, a filament current of 7-9mA, a high voltage energy of 480-520eV and a processing time of 10-20min.

[0028] According to some preferred embodiments of the present application, the single-layer graphene layer is grown and covered on the silicon substrate by the following steps:

[0029] A single-layer graphene layer is grown on a copper foil, the single-layer graphene layer is peeled off from the copper foil and is covered on one side surface of the silicon substrate with a Si3N4 layer by wet transfer.

[0030] According to some preferred embodiments of the present application, the single-layer graphene layer is grown by the following steps:

[0031] The copper foil is placed in a quartz tube furnace at a temperature of 1000-1200° C., hydrogen gas with a flow rate of 10-15 sccm is introduced into the quartz tube furnace, and annealed for 10-25 minutes;

[0032] Under a pressure of 1-3 torr, methane with a flow rate of 5-10 sccm and hydrogen with a flow rate of 50-100 sccm are introduced into the quartz tube furnace for 20-30 minutes to grow the single-layer graphene layer on the copper foil.

[0033] In some embodiments of the present invention, a method for remote epitaxially growing a nitride thin film on a silicon substrate specifically comprises the following steps:

[0034] Cleaning the surface of the silicon substrate;

[0035] Placing the cleaned silicon substrate in an MBE vacuum chamber, introducing argon gas into the MBE vacuum chamber, and etching the oxide layer on the surface of the cleaned silicon substrate using the argon gas;

[0036] Performing a surface nitridation treatment on the silicon substrate in the MBE vacuum chamber to form a Si3N4 layer on the surface of the silicon substrate;

[0037] Growing a single graphene layer on copper foil;

[0038] The single-layer graphene layer is peeled off from the copper foil and covered on the surface of the silicon substrate having the Si3N4 layer by wet transfer to form a single-layer graphene / Si3N4 / Si structure;

[0039] A nitride thin film is remotely epitaxially grown on the single-layer graphene layer.

[0040] The present invention also provides a nitride film prepared by the above method and a semiconductor device including the nitride film.

[0041] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: the present invention provides a method for remote epitaxial growth of a nitride film on a silicon substrate, wherein a silicon substrate without charge transfer and spontaneous polarization is treated by surface nitridation treatment to form a Si3N4 layer on the surface of the silicon substrate; then a single-layer graphene layer is transferred to the side of the silicon substrate having the Si3N4 layer; and then a remote epitaxial method is used to remotely epitaxially grow a nitride film on the single-layer graphene layer, thereby realizing remote epitaxial growth of a nitride film on a silicon substrate, overcoming the existing defect that a nitride film cannot be remotely epitaxially grown on a silicon substrate; in addition, by growing a nitride film on a silicon substrate by remote epitaxial means, the lattice structure information of the epitaxially grown nitride film is achieved to be the same as the lattice structure information of the Si3N4 layer on the surface of the silicon substrate, which can alleviate the large lattice mismatch and thermal mismatch existing when epitaxially growing a nitride film on a silicon substrate, and can obtain a high-quality nitride film based on a silicon substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 1 is a flow chart of the steps of a method for remote epitaxial growth of a nitride thin film on a silicon substrate according to a preferred embodiment of the present invention;

[0044] Figure 2 1 is a schematic diagram of a method for remote epitaxially growing a nitride thin film on a silicon substrate according to a preferred embodiment of the present invention;

[0045] FIG3(a) is an AFM (Atomic Force Microscope) photograph of a silicon substrate before surface argon etching according to a preferred embodiment of the present invention; FIG3(b) is an AFM photograph of a silicon substrate after surface argon etching according to a preferred embodiment of the present invention;

[0046] Figure 4 It is an atomic structure diagram and charge density contour map of the substrate before and after nitridation treatment in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0048] Patent CN201810714565.4 discloses a method for growing a single-crystal gallium nitride thin film on a Si(100) substrate, comprising: forming an amorphous SiO2 layer on the Si(100) substrate; transferring single-crystal graphene to a Si(100) / SiO2 substrate; pretreating the surface of the single-crystal graphene to produce dangling bonds; growing an AlN nucleation layer; and epitaxially growing a GaN thin film. However, this patent still suffers from the problem of weak graphene dangling bonds. The quality of the epitaxial layer produced by van der Waals epitaxy is inferior to that of remote epitaxy. Furthermore, the AlN buffer layer and the GaN thin film cannot be separated during epitaxial layer stripping, resulting in a complex film composition.

[0049] For example, patent CN202310515409.6 discloses a method for epitaxially growing nitride materials on graphene using silicon nitride as a mask layer. The method comprises the following steps: selecting a single crystal substrate, transferring or growing multilayer graphene on the single crystal substrate, forming a porous silicon nitride mask layer on the graphene, and epitaxially growing nitride materials at the windows. However, the patent uses silicon nitride as a mask layer, which cannot reduce the stress generated during lateral epitaxy. Compared with the growth mode of remote epitaxy on single-layer graphene, the epitaxial layer stress is higher, and peeling transfer cannot be achieved, which is not conducive to subsequent research such as the preparation of flexible devices.

[0050] Based on this, the present invention provides a method for remote epitaxial growth of nitride films on silicon substrates, which uses plasma (such as nitrogen) to treat the surface of the silicon substrate to obtain a Si3N4 layer on the surface of the silicon substrate, breaking the state of no potential fluctuation on the original silicon substrate surface, and then transferring a two-dimensional material layer (i.e., a single-layer graphene layer) to alleviate the large lattice mismatch and thermal mismatch of the nitride film to improve the quality of the nitride film, which can be applied in the field of CMOS integration; and then using MOCVD (Metal-organic Chemical Vapor Deposition, metal organic compound chemical vapor deposition) to remotely epitaxially grow high-quality nitride films (such as gallium nitride or aluminum nitride, etc.) on the single-layer graphene layer. For details, please refer to Figure 1 and Figure 2 The method for remote epitaxial growth of a nitride thin film on a silicon substrate provided by the present invention comprises the following steps:

[0051] S1: Prepare silicon substrate.

[0052] The silicon substrate in the present invention is a single crystal silicon substrate with a (100) plane.

[0053] S2: Surface treatment of the silicon substrate.

[0054] Surface treatment specifically includes the following steps:

[0055] S21: Cleaning the surface of the silicon substrate.

[0056] The silicon substrate is organically cleaned, specifically, firstly ultrasonically cleaned in an acetone solution for 5-10 minutes, then ultrasonically cleaned in an isopropyl alcohol solution for 5-10 minutes, and finally ultrasonically cleaned in water for 5-10 minutes.

[0057] S22: placing the cleaned silicon substrate in an MBE vacuum chamber, introducing argon gas into the MBE vacuum chamber, and etching the oxide layer on the surface of the cleaned silicon substrate using the argon gas.

[0058] The material of the oxide layer is SiO2, and the cleaned silicon substrate can be etched by argon etching. The process conditions of argon etching include a pressure of 4.5-5.5×10 6 torr, temperature of 380-420°C, filament current of 7-9 mA, high voltage energy of 480-520 eV, and processing time of 10-20 min.

[0059] Furthermore, after the argon etching is completed, the temperature within the MBE vacuum chamber can be raised to 500-650°C, and the silicon substrate can be annealed for 25-35 minutes to repair the surface lattice of the silicon substrate. Specifically, the present invention performs argon etching within the MBE vacuum chamber to etch away the surface oxide layer, and then anneals the surface to flatten and repair the lattice, further improving the surface flatness of the silicon substrate.

[0060] After the above treatment, N-Plasma etching is directly performed in the MBE chamber.

[0061] The present invention uses argon to etch SiO2. Annealing, N-Plasma etching, and subsequent growth processes can be performed within the same device. Compared to atomic layer etching (ALE), this in-situ etching process reduces the contact between the substrate and the external environment, preventing subsequent oxidation by oxygen in the air. Argon etching is also fast, low-cost, requires little equipment, is simple to operate, and the process is easy to control and implement. However, due to the poor selectivity of argon etching, it is prone to etching sputtering effects between materials, resulting in an uneven etched surface. The present invention uses annealing to repair lattice damage, reduce surface defects caused by argon etching, improve surface flatness, and enable nitrogen plasma to more uniformly nitride the substrate surface. This is shown in Figure 3(b).

[0062] S3: performing surface nitridation treatment on the silicon substrate to form a Si3N4 layer on the surface of the silicon substrate.

[0063] Surface nitriding treatment includes the following steps:

[0064] S31: placing the silicon substrate in a vacuum chamber of an MBE, setting the temperature to 420-550° C., and introducing nitrogen gas at a flow rate of 0.9-1.8 sccm into the vacuum chamber; wherein, the duration of the nitrogen gas is 4-7 minutes.

[0065] S32: treating the silicon substrate with nitrogen-containing plasma at a power of 220-370 W for 10-24 minutes.

[0066] S33: Raise the temperature to 500-650° C., perform annealing for 25-35 minutes, and then turn off the nitrogen gas source and the nitrogen-containing plasma RF source.

[0067] S34: After the temperature in the vacuum chamber drops to room temperature, the silicon substrate after the nitridation treatment is taken out; wherein, the silicon substrate after the nitridation treatment has a Si3N4 layer on at least one side of the surface.

[0068] The present invention uses nitrogen plasma to treat the surface of a silicon substrate, creating a Si3N4 layer on at least one side of the substrate. This layer creates a periodic Si-N bond pattern on the termination surface. Compared to a single silicon substrate, the Si3N4 layer exhibits surface potential fluctuations, which can induce charge redistribution on the surface of the two-dimensional graphene material, enabling the remote epitaxial growth of nitride thin films on the silicon substrate.

[0069] S4: growing a single graphene layer on copper foil.

[0070] The material of the single-layer graphene layer can be single-crystal graphene or polycrystalline graphene; growing a single-layer graphene includes the following steps:

[0071] S41: placing the copper foil in a quartz tube furnace at a temperature of 1000-1200° C., introducing hydrogen gas at a flow rate of 10-15 sccm into the quartz tube furnace, and annealing for 10-25 minutes.

[0072] S42: Under a pressure of 1-3 torr, methane with a flow rate of 5-10 sccm and hydrogen with a flow rate of 50-100 sccm are introduced into the quartz tube furnace for 20-30 minutes to grow a single layer of graphene on the copper foil.

[0073] S5: transferring the single-layer graphene layer onto the surface of the silicon substrate having the Si3N4 layer.

[0074] A single-layer graphene layer was adhered using polymethylmethacrylate (PMMA) and peeled off from the copper foil, and then covered on a Si3N4 layer / silicon substrate by wet transfer to form a single-layer graphene / Si3N4 / Si structure.

[0075] The present invention alleviates the lattice mismatch of the substrate by transferring two-dimensional materials (single-layer graphene); the (100) silicon substrate without surface nitridation treatment has no potential fluctuation on its surface and has no effect on graphene, while the Si3N4 layer is formed on the surface of the silicon substrate after nitridation treatment. The surface charge distribution of the Si3N4 layer is uneven and has potential fluctuation, which can induce charge redistribution on the graphene surface and is beneficial to the subsequent epitaxial growth of nitride.

[0076] S6: Remote epitaxial growth of a nitride film on the graphene layer.

[0077] The nitride film can be a single crystal nitride film. The lattice information of the nitride film is the same as the lattice structure information of the Si3N4 layer, preferably a hexagonal system, more preferably a hexagonal wurtzite structure. The remote epitaxy in the present invention means that the lattice information of the Si3N4 layer can affect the surface potential of the graphene, and further epitaxially grow an epitaxial layer with the same lattice information as the Si3N4 layer on the graphene layer.

[0078] The nitride thin film of the present invention may specifically be gallium nitride or aluminum nitride.

[0079] In some embodiments, when the material of the nitride film is gallium nitride, remote epitaxial nitride growth includes the following steps:

[0080] S61a: Under the condition of temperature of 600-800° C., a nitrogen source with a flow rate of 8000-14000 sccm, a gallium source with a flow rate of 30-80 sccm, and a carrier gas are introduced, and the reaction is carried out for 5-30 minutes to grow a nucleation layer.

[0081] The gallium source is trimethylgallium (TMGa), the nitrogen source is NH3, and the carrier gas is a mixed gas consisting of nitrogen with a flow rate of 400 sccm-600 sccm and hydrogen with a flow rate of 40 sccm-60 sccm.

[0082] S62a: Under the condition of a temperature of 1000-1200°C, a nitrogen source with a flow rate of 5000-8000sccm, a gallium source with a flow rate of 30-90sccm and a carrier gas are introduced, and the reaction is carried out for 150-200 minutes to grow a thin film layer on the nucleation layer to obtain a nitride thin film (i.e., gallium nitride thin film).

[0083] In some other embodiments, when the material of the nitride film is aluminum nitride, the remote epitaxial nitride growth includes the following steps:

[0084] S61b: Under the condition of temperature of 800-1100° C., a nitrogen source with a flow rate of 8000-14000 sccm, an aluminum source with a flow rate of 30-80 sccm and a carrier gas are introduced, and the reaction is carried out for 5-30 minutes to grow a nucleation layer.

[0085] The aluminum source is trimethylaluminium (TMAl), the nitrogen source is NH3, and the carrier gas is a mixed gas consisting of nitrogen with a flow rate of 400 sccm-600 sccm and hydrogen with a flow rate of 40 sccm-60 sccm.

[0086] S62b: Under the condition of a temperature of 1200-1400℃, a nitrogen source with a flow rate of 5000-8000sccm, an aluminum source with a flow rate of 30-90sccm and a carrier gas are introduced, and the reaction is carried out for 150-200 minutes to grow a thin film layer on the nucleation layer to obtain a nitride film (i.e., aluminum nitride film).

[0087] The nitride thin film prepared by the above method can be applied to semiconductor devices.

[0088] Example 1

[0089] See also Figure 1 and Figure 2 The method for remote epitaxial growth of a nitride thin film on a silicon substrate of this embodiment comprises the following specific steps:

[0090] S1: Prepare silicon substrate.

[0091] The silicon substrate in this embodiment is a (100)-plane single crystal silicon substrate.

[0092] S2: Surface treatment of the silicon substrate.

[0093] S21: Cleaning the surface of the silicon substrate.

[0094] The silicon substrate was subjected to organic cleaning, including ultrasonic cleaning in an acetone solution for 5 minutes, ultrasonic cleaning in an isopropyl alcohol solution for 5 minutes, and finally ultrasonic cleaning in water for 5 minutes.

[0095] S22: placing the cleaned silicon substrate in an MBE vacuum chamber, introducing argon gas into the MBE vacuum chamber, and etching the oxide layer on the surface of the cleaned silicon substrate using the argon gas.

[0096] The material of the oxide layer is SiO2, and the cleaned silicon substrate can be etched by using an argon etching method. The process conditions of the argon etching in this embodiment include a pressure of 5×10 6torr, a temperature of 400°C, a filament current of 8 mA, a high voltage energy of 500 eV, and a processing time of 15 min.

[0097] S23: After the argon etching is completed, the temperature in the MBE vacuum chamber is increased to 600° C., and the silicon substrate is annealed for 30 minutes to repair the surface lattice of the silicon substrate.

[0098] In this embodiment, argon etching was performed in an MBE vacuum chamber to etch away the surface oxide layer, followed by annealing to flatten the surface and repair the crystal lattice, further improving the surface flatness of the silicon substrate. For example, Figure 3(a) shows an AFM photograph of the silicon substrate before argon etching, while Figure 3(b) shows an AFM photograph of the silicon substrate after argon etching and annealing. The RMS (Root Mean Square) surface roughness of the silicon substrate in Figure 3(a) is 1.082nm, while the RMS surface roughness of the silicon substrate in Figure 3(b) is 0.487nm. After argon etching and annealing, the RMS surface roughness of the silicon substrate is reduced.

[0099] S3: performing surface nitridation treatment on the silicon substrate to form a Si3N4 layer on the surface of the silicon substrate.

[0100] Surface nitriding treatment includes the following steps:

[0101] S31: placing the silicon substrate in a vacuum chamber of an MBE, setting the temperature to 500° C., and introducing nitrogen gas at a flow rate of 1.5 sccm into the vacuum chamber; wherein, the duration of the nitrogen gas is 5 minutes.

[0102] S32: The silicon substrate is treated with nitrogen-containing plasma at a power of 300 W for 20 minutes.

[0103] S33: After the nitrogen-containing plasma treatment is completed, the temperature is raised to 600°C and annealed for 30 minutes, and then the N2 gas source and the nitrogen-containing plasma RF source are turned off to stabilize the Si3N4 layer on the surface of the silicon substrate, repair the interface and reduce stress.

[0104] S34: After the temperature in the vacuum chamber drops to room temperature, the silicon substrate after the nitridation treatment is taken out; wherein, the silicon substrate after the nitridation treatment has a Si3N4 layer on at least one side of the surface.

[0105] S4: growing a single graphene layer on copper foil.

[0106] The material of the single-layer graphene layer can be single-crystal graphene or polycrystalline graphene; growing a single-layer graphene includes the following steps:

[0107] S41: placing the copper foil in a quartz tube furnace at a temperature of 1100° C., introducing hydrogen gas at a flow rate of 12 sccm into the quartz tube furnace, and annealing for 15 minutes;

[0108] S42: Under a pressure of 2 Torr, methane with a flow rate of 8 sccm and hydrogen with a flow rate of 80 sccm are introduced into the quartz tube furnace for 25 minutes to grow a single-layer graphene layer on the copper foil.

[0109] S5: Covering a single-layer graphene layer onto the surface of the silicon substrate having the Si3N4 layer.

[0110] After the growth of the single-layer graphene layer is completed, polymethyl methacrylate is used to adhere the graphene to peel the single-layer graphene layer from the copper foil, and then it is covered on the side surface of the silicon substrate with the Si3N4 layer by wet transfer to form a single-layer graphene / Si3N4 / Si structure.

[0111] The charge density contour diagrams of substrates without and with surface nitriding treatment are shown in Figure 2. Figure 4 As shown, SLG stands for single-layer graphene. Figure 4 (a) Figure 4 (b) The atomic structure diagram of SLG / Si and the charge density contour map of the substrate; Figure 4 (c) Figure 4 (d) are the atomic structure diagram of SLG / Si3N4 / Si and the charge density contour map of the substrate. In the charge density contour map, the charge density of graphene is subtracted from the total charge density of the system to eliminate the influence of the background charge density of graphene, thereby reflecting the planar charge density distribution of the substrate. Red represents the negative charge area and blue represents the positive charge area. Figure 4 As can be seen in the figure, in the SLG / Si system, the graphene surface shows almost no charge density redistribution from the silicon substrate. In contrast, in the SLG / Si3N4 / Si system, positive and negative charge regions are located on some top (T) and bridge (B) sites of the SLG. This is a manifestation of substrate-induced charge on the graphene, which can promote the adsorption and nucleation of gallium and nitrogen atoms, thereby achieving remote epitaxial growth.

[0112] S6: remotely epitaxially growing a nitride film on the graphene layer, wherein the lattice information of the nitride film is the same as the lattice structure information of the Si3N4 layer.

[0113] The material of the nitride film in this embodiment is gallium nitride, and the remote epitaxial nitride growth includes the following steps:

[0114] S61a: At a temperature of 700° C., a nitrogen source with a flow rate of 10,000 sccm, a gallium source with a flow rate of 60 sccm, and a carrier gas are introduced for a reaction of 20 minutes to grow a nucleation layer.

[0115] The gallium source is trimethylgallium, the nitrogen source is NH3, and the carrier gas is a mixed gas consisting of nitrogen with a flow rate of 500 sccm and hydrogen with a flow rate of 50 sccm.

[0116] S62a: At a temperature of 1100° C., a nitrogen source with a flow rate of 6000 sccm, a gallium source with a flow rate of 60 sccm, and a carrier gas are introduced, and the reaction is carried out for 180 minutes to grow a thin film layer on the nucleation layer to obtain a gallium nitride thin film.

[0117] Example 2

[0118] The difference between this embodiment and embodiment 1 lies in step S6. In this embodiment, the nitride film is aluminum nitride, and the remote epitaxial nitride growth includes the following steps:

[0119] S61b: Under the condition of temperature of 1000°C, a nitrogen source with a flow rate of 12000 sccm, an aluminum source with a flow rate of 60 sccm and a carrier gas are introduced for 20 minutes to grow a nucleation layer;

[0120] The aluminum source is trimethylaluminum, the nitrogen source is NH3, and the carrier gas is a mixed gas consisting of nitrogen with a flow rate of 500 sccm and hydrogen with a flow rate of 50 sccm.

[0121] S62b: At a temperature of 1300° C., a nitrogen source with a flow rate of 6000 sccm, an aluminum source with a flow rate of 60 sccm, and a carrier gas are introduced and reacted for 180 minutes to grow a thin film layer on the nucleation layer to obtain an aluminum nitride thin film.

[0122] Example 3

[0123] The method for remote epitaxial growth of a nitride thin film on a silicon substrate provided in this embodiment comprises the following specific steps:

[0124] S1: Prepare silicon substrate.

[0125] The silicon substrate in this embodiment is a (100)-plane single crystal silicon substrate.

[0126] S2: Surface treatment of the silicon substrate.

[0127] S21: Cleaning the surface of the silicon substrate.

[0128] First, ultrasonic cleaning was performed in acetone solution for 8 min, then ultrasonic cleaning was performed in isopropanol solution for 8 min, and finally ultrasonic cleaning was performed in water for 8 min.

[0129] S22: placing the cleaned silicon substrate in an MBE vacuum chamber, introducing argon gas into the MBE vacuum chamber, and etching the oxide layer on the surface of the cleaned silicon substrate using the argon gas.

[0130] The material of the oxide layer is SiO2, and the cleaned silicon substrate can be etched by using an argon etching method. The process conditions of the argon etching in this embodiment include a pressure of 4.5×10 6 torr, the temperature was 380°C, the filament current was 7 mA, the high voltage energy was 480 eV, and the processing time was 20 min.

[0131] S23: After the argon etching is completed, the temperature in the MBE vacuum chamber is increased to 500° C., and the silicon substrate is annealed for 35 minutes to repair the surface lattice of the silicon substrate.

[0132] In this embodiment, argon etching is performed in an MBE vacuum chamber to etch away the surface oxide layer, and then annealing is performed to flatten the surface and repair the crystal lattice, thereby further improving the surface flatness of the silicon substrate.

[0133] S3: performing surface nitridation treatment on the silicon substrate to form a Si3N4 layer on the surface of the silicon substrate.

[0134] Surface nitriding treatment includes the following steps:

[0135] S31: placing the silicon substrate in a vacuum chamber of an MBE, setting the temperature to 420° C., and introducing nitrogen gas at a flow rate of 0.9 sccm into the vacuum chamber; wherein, the duration of the nitrogen gas is 7 minutes.

[0136] S32: The silicon substrate is treated with nitrogen-containing plasma at a power of 220 W for 24 minutes.

[0137] S33: After the nitrogen-containing plasma treatment is completed, the temperature is raised to 500° C. and annealed for 35 minutes, and then the N2 gas source and the nitrogen-containing plasma RF source are turned off.

[0138] S34: After the temperature in the vacuum chamber drops to room temperature, the silicon substrate after the nitridation treatment is taken out; wherein, the silicon substrate after the nitridation treatment has a Si3N4 layer on at least one side of the surface.

[0139] S4: growing a single graphene layer on copper foil.

[0140] The material of the single-layer graphene layer can be single-crystal graphene or polycrystalline graphene; growing a single-layer graphene includes the following steps:

[0141] S41: placing the copper foil in a quartz tube furnace at a temperature of 1000° C., introducing hydrogen gas at a flow rate of 10 sccm into the quartz tube furnace, and annealing for 25 minutes;

[0142] S42: Under a pressure of 1 torr, methane with a flow rate of 5 sccm and hydrogen with a flow rate of 50 sccm are introduced into the quartz tube furnace for 30 minutes to grow a single-layer graphene layer on the copper foil.

[0143] S5: Covering a single-layer graphene layer onto the surface of the silicon substrate having the Si3N4 layer.

[0144] After the growth of the single-layer graphene layer is completed, polymethyl methacrylate is used to adhere the graphene to peel the single-layer graphene layer from the copper foil, and then it is covered on the side surface of the silicon substrate with the Si3N4 layer by wet transfer to form a single-layer graphene / Si3N4 / Si structure.

[0145] S6: remotely epitaxially growing a nitride film on the graphene layer, wherein the lattice information of the nitride film is the same as the lattice structure information of the Si3N4 layer.

[0146] The material of the nitride film in this embodiment is gallium nitride, and the remote epitaxial nitride growth includes the following steps:

[0147] S61 a: At a temperature of 600° C., a nitrogen source with a flow rate of 8000 sccm, a gallium source with a flow rate of 30 sccm, and a carrier gas are introduced for a reaction of 30 minutes to grow a nucleation layer.

[0148] The gallium source is trimethylgallium, the nitrogen source is NH3, and the carrier gas is a mixed gas consisting of nitrogen with a flow rate of 400 sccm and hydrogen with a flow rate of 40 sccm.

[0149] S62a: Under the condition of a temperature of 1000° C., a nitrogen source with a flow rate of 5000 sccm, a gallium source with a flow rate of 30 sccm, and a carrier gas are introduced and reacted for 200 minutes to grow a gallium nitride thin film on the nucleation layer.

[0150] Example 4

[0151] The difference between this embodiment and embodiment 3 lies in step S6. In this embodiment, the nitride film is aluminum nitride, and the remote epitaxial nitride growth includes the following steps:

[0152] S61b: Under the condition of temperature of 800°C, a nitrogen source with a flow rate of 8000 sccm, an aluminum source with a flow rate of 30 sccm, and a carrier gas are introduced for 30 minutes to grow a nucleation layer;

[0153] The aluminum source is trimethylaluminum, the nitrogen source is NH3, and the carrier gas is a mixed gas consisting of nitrogen with a flow rate of 400 sccm and hydrogen with a flow rate of 40 sccm.

[0154] S62b: At a temperature of 1200° C., a nitrogen source with a flow rate of 5000 sccm, an aluminum source with a flow rate of 30 sccm, and a carrier gas are introduced and reacted for 200 minutes to grow a thin film layer on the nucleation layer to obtain an aluminum nitride thin film.

[0155] Example 5

[0156] The method for remote epitaxial growth of a nitride thin film on a silicon substrate provided in this embodiment comprises the following specific steps:

[0157] S1: Prepare silicon substrate.

[0158] The silicon substrate in this embodiment is a (100)-plane single crystal silicon substrate.

[0159] S2: Surface treatment of the silicon substrate.

[0160] S21: Cleaning the surface of the silicon substrate.

[0161] First, ultrasonically clean the sample in acetone solution for 10 minutes, then ultrasonically clean the sample in isopropanol solution for 10 minutes, and finally ultrasonically clean the sample in water for 10 minutes.

[0162] S22: placing the cleaned silicon substrate in an MBE vacuum chamber, introducing argon gas into the MBE vacuum chamber, and etching the oxide layer on the surface of the cleaned silicon substrate using the argon gas.

[0163] The material of the oxide layer is SiO2, and the cleaned silicon substrate can be etched by using an argon etching method. The process conditions of the argon etching in this embodiment include a pressure of 5.5×10 6 torr, the temperature was 420°C, the filament current was 9 mA, the high voltage energy was 520 eV, and the processing time was 10 min.

[0164] S23: After the argon etching is completed, the temperature in the MBE vacuum chamber is increased to 650° C., and the silicon substrate is annealed for 25 minutes to repair the surface lattice of the silicon substrate.

[0165] In this embodiment, argon etching is performed in an MBE vacuum chamber to etch away the surface oxide layer, and then annealing is performed to flatten the surface and repair the crystal lattice, thereby further improving the surface flatness of the silicon substrate.

[0166] S3: performing surface nitridation treatment on the silicon substrate to form a Si3N4 layer on the surface of the silicon substrate.

[0167] Surface nitriding treatment includes the following steps:

[0168] S31: placing the silicon substrate in a vacuum chamber of an MBE, setting the temperature to 550° C., and introducing nitrogen gas at a flow rate of 1.8 sccm into the vacuum chamber; wherein, the duration of the nitrogen gas is 4 minutes.

[0169] S32: The silicon substrate is treated with nitrogen-containing plasma at a power of 370 W for 10 minutes.

[0170] S33: After the nitrogen-containing plasma treatment is completed, the temperature is raised to 650° C. and annealed for 25 minutes, and then the N2 gas source and the nitrogen-containing plasma RF source are turned off.

[0171] S34: After the temperature in the vacuum chamber drops to room temperature, the silicon substrate after the nitridation treatment is taken out; wherein, the silicon substrate after the nitridation treatment has a Si3N4 layer on at least one side of the surface.

[0172] S4: growing a single graphene layer on copper foil.

[0173] The material of the single-layer graphene layer can be single-crystal graphene or polycrystalline graphene; growing a single-layer graphene includes the following steps:

[0174] S41: placing the copper foil in a quartz tube furnace at a temperature of 1200° C., introducing hydrogen gas at a flow rate of 15 sccm into the quartz tube furnace, and annealing for 10 minutes;

[0175] S42: Under a pressure of 3 Torr, methane with a flow rate of 10 sccm and hydrogen with a flow rate of 100 sccm are introduced into the quartz tube furnace for 20 minutes to grow a single-layer graphene layer on the copper foil.

[0176] S5: Covering a single-layer graphene layer onto the surface of the silicon substrate having the Si3N4 layer.

[0177] After the growth of the single-layer graphene layer is completed, polymethyl methacrylate is used to adhere the graphene to peel the single-layer graphene layer from the copper foil, and then it is covered on the Si3N4 layer / silicon substrate surface by wet transfer to form a single-layer graphene / Si3N4 / Si structure.

[0178] S6: remotely epitaxially growing a nitride film on the graphene layer, wherein the lattice information of the nitride film is the same as the lattice structure information of the silicon substrate.

[0179] The material of the nitride film in this embodiment is gallium nitride, and the remote epitaxial nitride growth includes the following steps:

[0180] S61 a: At a temperature of 800° C., a nitrogen source with a flow rate of 14,000 sccm, a gallium source with a flow rate of 80 sccm, and a carrier gas are introduced for a reaction of 5 minutes to grow a nucleation layer.

[0181] The gallium source is trimethylgallium, the nitrogen source is NH3, and the carrier gas is a mixed gas consisting of nitrogen with a flow rate of 600 sccm and hydrogen with a flow rate of 60 sccm.

[0182] S62a: At a temperature of 1200° C., a nitrogen source with a flow rate of 8000 sccm, a gallium source with a flow rate of 90 sccm, and a carrier gas are introduced, and the reaction is carried out for 150 minutes to grow a thin film layer on the nucleation layer to obtain a gallium nitride thin film.

[0183] Example 6

[0184] The difference between this embodiment and embodiment 5 lies in step S6. In this embodiment, the nitride film is aluminum nitride, and the remote epitaxial nitride growth includes the following steps:

[0185] S61b: Under the condition of temperature of 1100° C., a nitrogen source with a flow rate of 14000 sccm, an aluminum source with a flow rate of 80 sccm, and a carrier gas are introduced for 5 minutes to grow a nucleation layer;

[0186] The aluminum source is trimethylaluminum, the nitrogen source is NH3, and the carrier gas is a mixed gas consisting of nitrogen with a flow rate of 600 sccm and hydrogen with a flow rate of 60 sccm.

[0187] S62b: At a temperature of 1400°C, a nitrogen source with a flow rate of 8000 sccm, an aluminum source with a flow rate of 90 sccm, and a carrier gas are introduced and reacted for 150 minutes to grow a thin film layer on the nucleation layer to obtain an aluminum nitride thin film.

[0188] The present invention utilizes surface nitridation modification and remote epitaxial growth methods to enable remote epitaxy on silicon substrates that are not suitable for remote epitaxy. This allows for remote epitaxial growth of nitride films on silicon substrates, improving the quality of the epitaxial films while also achieving CMOS compatibility. Compared to existing technologies, the present invention has the following advantages:

[0189] 1) The single-layer graphene layer and the nitride film of the present invention are not bonded by covalent bonds, but by weak electrostatic forces between van der Waals forces and covalent bonds, so as to achieve the growth of a nearly stress-free nitride film on a silicon substrate and improve the growth quality of the nitride film.

[0190] 2) There is a large thermal mismatch between the commonly used silicon substrate and the nitride film, resulting in poor quality of the epitaxial nitride film, which seriously affects the performance and reliability of the device. The present invention uses graphene, a highly thermally conductive material, to alleviate thermal stress during the epitaxial growth process and improve the quality of the nitride film.

[0191] 3) Directly peeling off the epitaxial nitride film on the silicon substrate is difficult and the peeling operation is complicated, resulting in a large number of defects and damage. The present invention grows a nitride film on a single graphene layer, which can make the lattice structure information of the nitride film consistent with the lattice structure information of the Si3N4 layer on the surface of the silicon substrate. This alleviates the large lattice mismatch and thermal mismatch that exist when epitaxially growing nitride films on silicon substrates, reducing the defects and stress caused by the lattice mismatch and thermal mismatch. At the same time, the weak electrostatic force between the single graphene layers facilitates the peeling of the nitride film, reducing the probability of defects and damage in the nitride film.

[0192] 4) The present invention utilizes nitrogen plasma to directly modify the surface of the silicon substrate, which is simple to operate, involves fewer steps, and is suitable for large-scale industrial promotion.

[0193] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

[0194] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

Claims

1. A method for remote epitaxial growth of a nitride thin film, characterized in that: The steps include: The silicon substrate is sequentially subjected to argon etching and annealing treatment, wherein the argon etching is used to remove the oxide layer on the surface of the silicon substrate, and the annealing treatment is used to repair the surface lattice of the silicon substrate; the silicon substrate is a single crystal silicon substrate with a (100) plane; Performing a surface nitriding treatment on a silicon substrate to form a Si3N4 layer on the surface of the silicon substrate; forming a single-layer graphene layer on a surface of a silicon substrate having a Si3N4 layer; wherein the surface of the Si3N4 layer has a potential fluctuation for inducing charge redistribution on the surface of the single-layer graphene layer; A nitride thin film is remotely epitaxially grown on the single-layer graphene layer.

2. The method according to claim 1, characterized in that The argon etching, annealing treatment, surface nitriding treatment and remote epitaxial growth of the nitride film are all carried out in the same equipment.

3. The method according to claim 1, characterized in that The argon etching comprises the following steps: placing a cleaned silicon substrate in an MBE vacuum chamber, introducing argon into the MBE vacuum chamber, and etching the oxide layer on the surface of the silicon substrate using the argon.

4. The method according to claim 1, wherein The process conditions of the argon etching include a pressure of 4.5-5.5×10 6 torr, temperature of 380-420°C, filament current of 7-9 mA, high voltage energy of 480-520 eV, and processing time of 10-20 min.

5. The method according to claim 1, wherein The annealing treatment comprises the following steps: raising the temperature in the MBE vacuum chamber to 500-650° C., and annealing the silicon substrate for 25-35 minutes to repair the surface lattice of the silicon substrate.

6. The method according to claim 1, characterized in that The surface nitriding treatment comprises the following steps: The silicon substrate is placed in an MBE vacuum chamber, the temperature is set to 420-550° C., and nitrogen gas with a flow rate of 0.9-1.8 sccm is introduced into the MBE vacuum chamber; wherein the duration of the nitrogen gas injection is 4-7 minutes; Treating the silicon substrate with nitrogen-containing plasma at a power of 220-370 W for 10-24 min; After the temperature in the MBE vacuum chamber drops to room temperature, the silicon substrate after nitridation is taken out; wherein, the silicon substrate after nitridation has a Si3N4 layer on at least one side of its surface.

7. The method according to claim 1, characterized in that Before the silicon substrate is argon-etched, the surface of the silicon substrate is cleaned by ultrasonic cleaning in an acetone solution for 5-10 minutes, ultrasonic cleaning in an isopropyl alcohol solution for 5-10 minutes, and ultrasonic cleaning in water for 5-10 minutes.

8. The method according to claim 1, characterized in that The single-layer graphene layer is grown and covered on the silicon substrate by the following steps: Growing a single graphene layer on copper foil; The single-layer graphene layer is peeled off from the copper foil and covered on the surface of the silicon substrate having the Si3N4 layer by wet transfer.

9. The method according to claim 8, characterized in that The single-layer graphene layer is grown by the following steps: The copper foil is placed in a quartz tube furnace at a temperature of 1000-1200° C., hydrogen gas with a flow rate of 10-15 sccm is introduced into the quartz tube furnace, and annealed for 10-25 minutes; Under a pressure of 1-3 torr, methane with a flow rate of 5-10 sccm and hydrogen with a flow rate of 50-100 sccm are introduced into the quartz tube furnace for 20-30 minutes to grow the single-layer graphene layer on the copper foil.

10. The method according to claim 1, characterized in that The lattice information of the nitride film is the same as the lattice structure information of the Si3N4 layer; the nitride film is a gallium nitride film or an aluminum nitride film.

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