Method for remotely epitaxially growing nitride thin film on silicon substrate, nitride thin film and semiconductor device

Abstract

The present invention discloses a method for remotely epitaxially growing a nitride thin film on a silicon substrate, a nitride thin film and a semiconductor device. The method includes the following steps: performing surface nitridation treatment on the silicon substrate to form a Si3N4 layer on the surface of the silicon substrate; forming a single-layer graphene layer on one surface of the silicon substrate having the Si3N4 layer; remotely epitaxially growing a nitride thin film on the single-layer graphene layer; wherein the lattice information of the nitride thin film is the same as the lattice structure information of the Si3N4 layer. By adopting the technical solution provided by the present invention, it is possible to remotely epitaxially grow a nitride thin film on a silicon substrate.

Description

Technical Field

[0001] The present invention relates to the technical fields of remote epitaxy and third-generation semiconductor materials, and particularly relates to a method for remotely epitaxially growing a nitride thin film on a silicon substrate, a nitride thin film prepared by this method, and a semiconductor device including the nitride thin film. Background Art

[0002] In recent years, the heterogeneous integration of two-dimensional (2D) materials, especially graphene and nitrides, has broad application prospects in the fields of preparing flexible wearable devices and transferable electronic and photonic devices. Recently, a new epitaxy technology - remote epitaxy utilizes the "lattice transparency" of graphene to generate a remote electrostatic interaction between the substrate and the epitaxial layer. By virtue of this interaction, the epitaxial layer can "copy" the lattice information of the substrate through graphene, thus ensuring the lattice orientation consistency of the epitaxial layer. This method can not only alleviate the lattice mismatch caused by the substrate, but also the good thermal conductivity of graphene can alleviate the thermal mismatch between the epitaxial layer and the substrate, thereby preparing high-quality single-crystal nitride thin films. However, the silicon substrate itself does not have spontaneous polarization and the surface potential fluctuation is not large, resulting in that the surface potential of the silicon substrate cannot penetrate the two-dimensional material, and the charge on the surface of the two-dimensional material cannot be redistributed, so that it is impossible to epitaxially grow a nitride epitaxial layer with the same lattice information as the substrate on the two-dimensional material. At the same time, a large lattice mismatch also makes it difficult to epitaxially grow high-quality nitride thin films. Summary of the Invention

[0003] In view of this, one of the purposes of the present invention is to provide a method for remotely epitaxially growing a nitride thin film on a silicon substrate, which uses the means of surface nitridation treatment to enable the silicon substrate that cannot be remotely epitaxially grown to have the ability of remote epitaxy, and then remotely epitaxially grow a nitride thin film.

[0004] A method for remotely epitaxially growing a nitride thin film on a silicon substrate includes the following steps:

[0005] Perform surface nitridation treatment on the silicon substrate to form a Si 3 N 4 layer on the surface of the silicon substrate;

[0006] Form a single-layer graphene layer on one side surface of the silicon substrate having the Si 3 N 4 layer;

[0007] Remotely epitaxially grow a nitride thin film on the single-layer graphene layer;

[0008] Wherein, the lattice information of the nitride thin film is the same as the lattice structure information of the Si 3 N 4 layer.

[0009] Preferably, the nitride thin film and Si 3 N 4 layers both have a hexagonal crystal system, and more preferably a hexagonal wurtzite structure.

[0010] According to some preferred embodiments of the present invention, the surface nitriding treatment includes the following steps:

[0011] Place the silicon substrate in the vacuum chamber of MBE (Molecular Beam Epitaxy), set the temperature to 420 - 550 °C, and introduce nitrogen with a flow rate of 0.9 - 1.8 sccm into the MBE vacuum chamber; wherein, the duration of the nitrogen is 4 - 7 min;

[0012] Treat the silicon substrate with nitrogen-containing plasma at a power of 220 - 370 W for 10 - 24 min;

[0013] After the temperature in the vacuum chamber drops to room temperature, take out the silicon substrate after nitriding treatment; wherein, at least one side surface of the silicon substrate after nitriding treatment has a Si 3 N 4 layer. The currently disclosed surface nitriding treatment processes are only used to remove surface impurities or adsorbed oxygen, water molecules, etc., and repair lattice defects, such as nitrogen vacancies, etc. However, the surface treatment process of the present invention has a greater treatment power and longer time, aiming to form a Si 3 N 4 layer on at least one side surface of the silicon substrate.

[0014] According to some preferred embodiments of the present invention, the material of the nitride thin film is gallium nitride, and the remote epitaxial growth of the nitride thin film includes the following steps:

[0015] Under the condition of a temperature of 600 - 800 °C, introduce 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, and react for 5 - 30 min to grow a nucleation layer;

[0016] Under the condition of a temperature of 1000 - 1200 °C, introduce 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 react for 150 - 200 min to grow a thin film layer on the nucleation layer to obtain the nitride thin film;

[0017] Wherein, 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.

[0018] According to some preferred embodiments of the present invention, the material of the nitride thin film is aluminum nitride, and the remote epitaxial growth of the nitride thin film includes the following steps:

[0019] Under the condition that the temperature is 800 - 1100 °C, introduce 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, and react for 5 - 30 min to grow a nucleation layer;

[0020] Under the condition that the temperature is 1200 - 1400 °C, introduce a nitrogen source with a flow rate of 5000 - 8000 sccm, an aluminum source with a flow rate of 30 - 90 sccm, and a carrier gas, and react for 150 - 200 min to grow a thin film layer on the nucleation layer to obtain the nitride thin film;

[0021] Among them, 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.

[0022] According to some preferred embodiments of the present invention, the silicon substrate is a single - crystal silicon substrate with a (100) plane;

[0023] And / or, before the surface nitridation treatment of the silicon substrate, the following steps are included:

[0024] Perform surface cleaning on the silicon substrate;

[0025] Place the cleaned silicon substrate in an MBE vacuum chamber, introduce argon into the MBE vacuum chamber, use the argon to etch the oxide layer on the surface of the cleaned silicon substrate, and after the argon etching is completed, heat up and anneal to repair the surface lattice. That is, in the present invention, argon etching is carried out in the MBE vacuum chamber to etch the oxide layer on the surface of the cleaned silicon substrate, and then anneal to flatten the surface and repair the lattice, so as to further improve the surface flatness of the silicon substrate.

[0026] According to some preferred embodiments of the present invention, the process conditions of the argon etching include a pressure of 4.5 - 5.5×10 6 torr, a temperature of 380 - 420 °C, a filament current of 7 - 9 mA, a high - voltage energy of 480 - 520 eV, and a processing time of 10 - 20 min.

[0027] According to some preferred embodiments of the present invention, the single - layer graphene layer is grown and covered on the silicon substrate through the following steps:

[0028] Grow a single - layer graphene layer on a copper foil; peel the single - layer graphene layer from the copper foil and cover it on the silicon substrate with Si 3 N4 On one side surface of the layer.

[0029] According to some preferred embodiments of the present invention, the single-layer graphene layer is grown by the following steps:

[0030] Place the copper foil in a quartz tube furnace at a temperature of 1000 - 1200 °C, introduce hydrogen with a flow rate of 10 - 15 sccm into the quartz tube furnace, and anneal for 10 - 25 min;

[0031] Under the condition of a pressure of 1 - 3 torr, introduce methane with a flow rate of 5 - 10 sccm and hydrogen with a flow rate of 50 - 100 sccm into the quartz tube furnace, and maintain for 20 - 30 min to grow the single-layer graphene layer on the copper foil.

[0032] In some embodiments of the present invention, the method for remotely epitaxially growing a nitride film on a silicon substrate specifically includes the following steps:

[0033] Clean the surface of the silicon substrate;

[0034] Place the cleaned silicon substrate in an MBE vacuum chamber, introduce argon into the MBE vacuum chamber, and use the argon to etch the oxide layer on the surface of the cleaned silicon substrate;

[0035] Perform surface nitridation treatment on the silicon substrate in the MBE vacuum chamber to form a Si 3 N 4 layer on the surface of the silicon substrate;

[0036] Grow a single-layer graphene layer on the copper foil;

[0037] Peel the single-layer graphene layer from the copper foil and transfer it onto the surface of the silicon substrate with a Si 3 N 4 layer by wet transfer to form a single-layer graphene / Si 3 N 4 / Si structure;

[0038] Remotely epitaxially grow a nitride film on the single-layer graphene layer.

[0039] The present invention also provides a nitride film prepared by the above method and a semiconductor device including the nitride film.

[0040] Due to the application of the above technical solutions, the present invention has the following advantages compared with the prior art. The present invention provides a method for remotely epitaxially growing a nitride film on a silicon substrate, and uses the means of surface nitridation treatment to process a silicon substrate without charge transfer and spontaneous polarization to form a Si3 N 4 layer; then transfer the single-layer graphene layer onto the side of the silicon substrate having Si 3 N 4 layer; then use the method of remote epitaxy to remotely epitaxially grow a nitride thin film on the single-layer graphene layer, thereby realizing the remote epitaxial growth of a nitride thin film on the silicon substrate and overcoming the defect that the existing technology cannot remotely epitaxially grow a nitride thin film on the silicon substrate; in addition, by using the means of remote epitaxy to grow a nitride thin film on the silicon substrate, the lattice structure information of the epitaxially grown nitride thin film is made the same as that of the Si 3 N 4 layer on the silicon substrate surface, which can alleviate the large lattice mismatch and thermal mismatch existing during the epitaxial growth of a nitride thin film on the silicon substrate, and a high-quality nitride thin film based on the silicon substrate can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0042] Figure 1 is a flowchart of the steps of the method for remotely epitaxially growing a nitride thin film on a silicon substrate according to a preferred embodiment of the present invention;

[0043] Figure 2 is a growth schematic diagram of the method for remotely epitaxially growing a nitride thin film on a silicon substrate according to a preferred embodiment of the present invention;

[0044] FIG. 3(a) is an AFM (Atomic Force Microscope) photograph of the silicon substrate before surface argon etching according to a preferred embodiment of the present invention; FIG. 3(b) is an AFM photograph of the silicon substrate after surface argon etching according to a preferred embodiment of the present invention;

[0045] Figure 4 is the atomic structure diagram and charge density contour map before and after the substrate nitridation treatment according to a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] To enable those skilled in the art to better understand the solution 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 accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0047] Patent CN201810714565.4 discloses a method for growing single-crystalline gallium nitride thin film on a Si(100) substrate, including: forming an amorphous SiO 2 layer on the Si(100) substrate; transferring single-crystalline graphene onto the Si(100) / SiO 2 substrate; pre-treating the surface of the single-crystalline graphene to generate dangling bonds; growing an AlN nucleation layer; and epitaxially growing a GaN thin film. However, this patent still has the problem of relatively weak dangling bonds of graphene, and the quality of the epitaxial layer grown by van der Waals epitaxy is worse than that of the remote epitaxy scheme. Moreover, when stripping the epitaxial layer, the AlN buffer layer and the GaN thin film cannot be separated, and the film composition is complex.

[0048] Another example is that patent CN202310515409.6 discloses a method for epitaxially growing nitride materials on graphene using silicon nitride as a mask layer. The method includes the following steps: selecting a single-crystalline substrate, transferring or growing multiple layers of graphene on the single-crystalline substrate, forming a porous silicon nitride mask layer on the graphene, and epitaxially growing nitride materials at the window. However, this 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 a single layer of graphene, the stress of the epitaxial layer is higher, and stripping and transfer cannot be achieved, which is not conducive to subsequent research such as the preparation of flexible devices.

[0049] Based on this, the present invention provides a method for remotely epitaxially growing nitride thin films on a silicon substrate, using plasma (such as nitrogen) to treat the surface of the silicon substrate to obtain a Si 3 N 4 layer on the surface of the silicon substrate, breaking the state of no potential fluctuation on the surface of the original silicon substrate, and then transferring a two-dimensional material layer (i.e., a single layer of graphene layer) to relieve the large lattice mismatch and thermal mismatch of the nitride thin film, so as to improve the quality of the nitride thin film and be applicable in the field of CMOS integration; then using MOCVD (Metal-organic Chemical Vapor Deposition) to remotely epitaxially grow high-quality nitride thin films (such as gallium nitride or aluminum nitride, etc.) on the single layer of graphene layer. Specifically, please refer to Figure 1 And Figure 2, the method for remotely epitaxially growing nitride thin films on a silicon substrate provided by the present invention includes the following steps:

[0050] S1: Prepare a silicon substrate.

[0051] The silicon substrate in the present invention is a single-crystalline silicon substrate with a (100) plane.

[0052] S2: Perform surface treatment on the silicon substrate.

[0053] The surface treatment specifically includes the following steps:

[0054] S21: Clean the surface of the silicon substrate.

[0055] Perform organic cleaning on the silicon substrate. Specifically, place the silicon substrate in an acetone solution for ultrasonic cleaning for 5 - 10 min, then in an isopropyl alcohol solution for ultrasonic cleaning for 5 - 10 min, and finally in water for ultrasonic cleaning for 5 - 10 min.

[0056] S22: Place the cleaned silicon substrate in an MBE vacuum chamber, introduce argon gas into the MBE vacuum chamber, and use the argon gas to etch the oxide layer on the surface of the cleaned silicon substrate.

[0057] The material of the oxide layer is SiO 2 , the cleaned silicon substrate can be etched by the method of argon gas etching. The process conditions of argon gas etching include a pressure of 4.5 - 5.5×10 6 torr, a temperature of 380 - 420 °C, a filament current of 7 - 9 mA, a high-voltage energy of 480 - 520 eV, and a processing time of 10 - 20 min.

[0058] Furthermore, after the argon gas etching is completed, the temperature in the MBE vacuum chamber can be raised to 500 - 650 °C, and the silicon substrate is annealed for 25 - 35 min to repair the surface lattice of the silicon substrate. That is, in the present invention, argon etching is performed in the MBE vacuum chamber to etch away the surface oxide layer, and then annealing is performed to flatten the surface and repair the lattice, further improving the surface flatness of the silicon substrate.

[0059] After the above treatment, directly perform N-Plasma etching in the MBE chamber.

[0060] The present invention uses argon gas to etch SiO 2, annealing, N-Plasma etching, and subsequent growth processes can be carried out in the same device. This in-situ etching process reduces the contact between the substrate and the external environment compared to atomic layer etching (ALE), avoids subsequent oxidation by oxygen in the air, and has a fast argon etching speed, low cost, low equipment requirements, simple operation, and easy process control and implementation. However, due to the poor selectivity of argon etching, it is prone to etching sputtering effects between materials, resulting in an uneven etched surface. In the present invention, annealing is used to repair lattice damage, reduce surface defects caused by argon etching, improve surface flatness, and enable nitrogen plasma to nitride the substrate surface more uniformly. As shown in Figure 3(b).

[0061] S3: Perform surface nitridation treatment on the silicon substrate to form a Si 3 N 4 layer on the surface of the silicon substrate.

[0062] The surface nitridation treatment includes the following steps:

[0063] S31: Place the silicon substrate in the vacuum chamber of MBE, set the temperature to 420 - 550 °C, and introduce nitrogen with a flow rate of 0.9 - 1.8 sccm into the vacuum chamber; among them, the duration of nitrogen is 4 - 7 min.

[0064] S32: Treat the silicon substrate with nitrogen-containing plasma at a power of 220 - 370 W for 10 - 24 min.

[0065] S33: Raise the temperature to 500 - 650 °C, perform annealing treatment for 25 - 35 min, and then turn off the nitrogen gas source and the radio frequency source of the nitrogen-containing plasma.

[0066] S34: Take out the nitrided silicon substrate after the temperature in the vacuum chamber drops to room temperature; among them, at least one side surface of the nitrided silicon substrate has a Si 3 N 4 layer.

[0067] The present invention uses nitrogen plasma to treat the surface of the silicon substrate so that at least one side surface of the silicon substrate has a Si 3 N 4 layer, making the termination surface present Si-N bonds with lattice periodicity. Compared with the single-crystal silicon substrate, the Si 3 N 4 layer surface has potential fluctuations, which can induce charge redistribution on the surface of the two-dimensional material graphene, thereby realizing the remote epitaxial growth of nitride thin films on the silicon substrate.

[0068] S4: Grow a single-layer graphene layer on the copper foil.

[0069] The material of the single-layer graphene layer can be single-crystal graphene or polycrystalline graphene; growing the single-layer graphene includes the following steps:

[0070] S41: Place the copper foil in a quartz tube furnace at a temperature of 1000 - 1200 °C, introduce hydrogen with a flow rate of 10 - 15 sccm into the quartz tube furnace, and anneal for 10 - 25 min.

[0071] S42: Under the condition of a pressure of 1 - 3 torr, introduce methane with a flow rate of 5 - 10 sccm and hydrogen with a flow rate of 50 - 100 sccm into the quartz tube furnace, and maintain for 20 - 30 min to grow a single-layer graphene layer on the copper foil.

[0072] S5: Transfer the single-layer graphene layer to the surface of the silicon substrate with an Si 3 N 4 layer.

[0073] Use polymethyl methacrylate (PMMA) to adhere the single-layer graphene layer and peel the single-layer graphene layer from the copper foil, and cover it on the Si 3 N 4 layer / silicon substrate through wet transfer to form a single-layer graphene / Si 3 N 4 / Si structure.

[0074] The present invention alleviates the lattice mismatch of the substrate by transferring two-dimensional materials (single-layer graphene); for a (100) silicon substrate without surface nitridation treatment, its surface has no potential fluctuation and has no interaction with graphene, while after nitridation treatment, an Si 3 N 4 layer is formed on the surface of the silicon substrate. The surface charge distribution of the Si 3 N 4 layer is uneven, with potential fluctuations, which can induce charge redistribution on the surface of graphene and is conducive to the subsequent epitaxial growth of nitrides.

[0075] S6: Remotely epitaxially grow a nitride film on the graphene layer.

[0076] The nitride film can be a single-crystal nitride film. The lattice information of the nitride film is the same as that of the Si 3 N 4 layer, preferably a hexagonal crystal system, and more preferably a hexagonal wurtzite structure. The remote epitaxy in the present invention means that the lattice information of the Si 3 N 4 layer can affect the surface potential of graphene, and further epitaxially grow an epitaxial layer with the same lattice information as the Si 3 N 4 layer on the graphene layer.

[0077] The nitride thin film of the present invention may specifically be gallium nitride or aluminum nitride.

[0078] In some embodiments, when the material of the nitride thin film is gallium nitride, the remote epitaxial nitride includes the following steps:

[0079] S61a: Under the condition that the temperature is 600 - 800 °C, introduce 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, and react for 5 - 30 min to grow a nucleation layer.

[0080] The gallium source is trimethylgallium (TMGa), and the nitrogen source is NH 3 , and the carrier gas is a mixed gas composed of nitrogen with a flow rate of 400 sccm - 600 sccm and hydrogen with a flow rate of 40 sccm - 60 sccm.

[0081] S62a: Under the condition that the temperature is 1000 - 1200 °C, introduce 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 react for 150 - 200 min to grow a thin film layer on the nucleation layer to obtain a nitride thin film (i.e., a gallium nitride thin film).

[0082] In other embodiments, when the material of the nitride thin film is aluminum nitride, the remote epitaxial nitride includes the following steps:

[0083] S61b: Under the condition that the temperature is 800 - 1100 °C, introduce 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, and react for 5 - 30 min to grow a nucleation layer.

[0084] The aluminum source is trimethylaluminium (TMAl), and the nitrogen source is NH 3 , and the carrier gas is a mixed gas composed of nitrogen with a flow rate of 400 sccm - 600 sccm and hydrogen with a flow rate of 40 sccm - 60 sccm.

[0085] S62b: Under the condition that the temperature is 1200 - 1400 °C, introduce a nitrogen source with a flow rate of 5000 - 8000 sccm, an aluminum source with a flow rate of 30 - 90 sccm, and a carrier gas, and react for 150 - 200 min to grow a thin film layer on the nucleation layer to obtain a nitride thin film (i.e., an aluminum nitride thin film).

[0086] The nitride thin film prepared by the above method can be applied to semiconductor devices.

[0087] Example 1

[0088] Please refer to Figure 1 and Figure 2 , the method for remotely epitaxially growing nitride thin films on a silicon substrate in this example is as follows:

[0089] S1: Prepare a silicon substrate.

[0090] The silicon substrate in this example is a single-crystalline silicon substrate with a (100) plane.

[0091] S2: Perform surface treatment on the silicon substrate.

[0092] S21: Clean the surface of the silicon substrate.

[0093] Perform organic cleaning on the silicon substrate, including ultrasonic cleaning in an acetone solution for 5 min, then ultrasonic cleaning in an isopropyl alcohol solution for 5 min, and finally ultrasonic cleaning in water for 5 min.

[0094] S22: Place the cleaned silicon substrate in an MBE vacuum chamber, introduce argon gas into the MBE vacuum chamber, and use argon gas to etch the oxide layer on the surface of the cleaned silicon substrate.

[0095] The material of the oxide layer is SiO 2 , and the cleaned silicon substrate can be etched by using argon gas etching. The process conditions of argon gas etching in this example include a pressure of 5×10 6 torr, 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.

[0096] S23: After the argon gas etching is completed, raise the temperature in the MBE vacuum chamber to 600°C and anneal the silicon substrate for 30 min to repair the surface lattice of the silicon substrate.

[0097] In this example, argon etching was performed in the MBE vacuum chamber to etch away the surface oxide layer, and then annealing was carried out to flatten the surface and repair the lattice, further improving the surface flatness of the silicon substrate. For example, Figure 3(a) is an AFM photograph of the silicon substrate without surface argon etching, and Figure 3(b) is an AFM photograph of the silicon substrate after surface argon etching and annealing; the surface roughness RMS (Root Mean Square) of the silicon substrate in Figure 3(a) is 1.082 nm, and the surface roughness RMS of the silicon substrate in Figure 3(b) is 0.487 nm. After argon etching and annealing treatment, the surface roughness RMS of the silicon substrate becomes smaller.

[0098] S3: Perform surface nitridation treatment on the silicon substrate to form a Si 3 N 4 layer on the surface of the silicon substrate.

[0099] The surface nitridation treatment includes the following steps:

[0100] S31: Place the silicon substrate in the vacuum chamber of MBE, set the temperature to 500 °C, and introduce nitrogen with a flow rate of 1.5 sccm into the vacuum chamber; wherein, the duration of nitrogen is 5 min.

[0101] S32: Treat the silicon substrate with nitrogen-containing plasma at a power of 300 W for 20 min.

[0102] S33: After the nitrogen-containing plasma treatment, heat up to 600 °C and anneal for 30 min, then turn off the N 2 gas source and the nitrogen-containing plasma radio frequency source to stabilize the Si 3 N 4 layer on the surface of the silicon substrate, repair the interface and reduce stress.

[0103] S34: Take out the nitrided silicon substrate after the temperature in the vacuum chamber drops to room temperature; wherein, at least one side surface of the nitrided silicon substrate has a Si 3 N 4 layer.

[0104] S4: Grow a single-layer graphene layer on the copper foil.

[0105] The material of the single-layer graphene layer can be single-crystal graphene or polycrystalline graphene; growing a single-layer graphene layer includes the following steps:

[0106] S41: Place the copper foil in a quartz tube furnace at a temperature of 1100 °C, introduce hydrogen with a flow rate of 12 sccm into the quartz tube furnace, and anneal for 15 min;

[0107] S42: Under the condition of a pressure of 2 torr, introduce methane with a flow rate of 8 sccm and hydrogen with a flow rate of 80 sccm into the quartz tube furnace, and maintain for 25 min to grow a single-layer graphene layer on the copper foil.

[0108] S5: Cover the single-layer graphene layer on the surface of the silicon substrate with a Si 3 N 4 layer.

[0109] After the growth of the single-layer graphene layer is completed, use polymethyl methacrylate to adhere to the graphene to peel the single-layer graphene layer from the copper foil, and cover it on one side surface of the silicon substrate with a Si 3 N 4 layer through wet transfer to form a single-layer graphene / Si 3 N 4 / Si structure.

[0110] Charge density contour plots of substrates without and with surface nitridation treatment are shown as Figure 4 follows, where SLG represents single-layer graphene. Among them, Figure 4 (a) of Figure 4 is the atomic structure diagram of SLG / Si and the substrate charge density contour plot; Figure 4 (c) of Figure 4 and 3 N 4 (d) of Figure 4 are the atomic structure diagram of SLG / Si 3 N 4 / Si and the substrate charge density contour plot. In the charge density contour plot, the background charge density of graphene is eliminated by subtracting the graphene charge density from the total charge density of the system, so as to reflect the planar charge density distribution of the substrate. Red represents the negative charge region, and blue represents the positive charge region. It can be seen from

[0111] S6: Remotely epitaxially grow a nitride film on the graphene layer, and the lattice information of the nitride film is the same as that of the Si 3 N 4 layer.

[0112] In this embodiment, the material of the nitride film is gallium nitride, and the remote epitaxial nitride includes the following steps:

[0113] S61a: Under the condition of a temperature of 700 °C, introduce a nitrogen source with a flow rate of 10000 sccm, a gallium source with a flow rate of 60 sccm, and a carrier gas, and react for 20 min to grow a nucleation layer.

[0114] The gallium source is trimethylgallium, the nitrogen source is NH 3 , and the carrier gas is a mixed gas composed of nitrogen with a flow rate of 500 sccm and hydrogen with a flow rate of 50 sccm.

[0115] S62a: Under the condition of a temperature of 1100 °C, introduce a nitrogen source with a flow rate of 6000 sccm, a gallium source with a flow rate of 60 sccm, and a carrier gas, and react for 180 min to grow a film layer on the nucleation layer to obtain a gallium nitride film.

[0116] Example 2

[0117] The difference between this embodiment and Embodiment 1 lies in the difference of Step S6. The nitride film in this embodiment is aluminum nitride. The remote epitaxial growth of nitride includes the following steps:

[0118] S61b: Under the condition that the temperature is 1000 °C, introduce a nitrogen source with a flow rate of 12000 sccm, an aluminum source with a flow rate of 60 sccm, and a carrier gas, and react for 20 min to grow a nucleation layer;

[0119] The aluminum source is trimethylaluminum, and the nitrogen source is NH 3 , and the carrier gas is a mixed gas composed of nitrogen with a flow rate of 500 sccm and hydrogen with a flow rate of 50 sccm.

[0120] S62b: Under the condition that the temperature is 1300 °C, introduce a nitrogen source with a flow rate of 6000 sccm, an aluminum source with a flow rate of 60 sccm, and a carrier gas, and react for 180 min to grow a film layer on the nucleation layer to obtain an aluminum nitride film.

[0121] Embodiment 3

[0122] The method for remotely epitaxially growing a nitride film on a silicon substrate provided in this embodiment specifically includes the following steps:

[0123] S1: Prepare a silicon substrate.

[0124] The silicon substrate in this embodiment is a single-crystalline silicon substrate with a (100) plane.

[0125] S2: Perform surface treatment on the silicon substrate.

[0126] S21: Clean the surface of the silicon substrate.

[0127] First, ultrasonically clean in an acetone solution for 8 min, then ultrasonically clean in an isopropyl alcohol solution for 8 min, and finally ultrasonically clean in water for 8 min.

[0128] S22: Place the cleaned silicon substrate in an MBE vacuum chamber, introduce argon into the MBE vacuum chamber, and use argon to etch the oxide layer on the surface of the cleaned silicon substrate.

[0129] The material of the oxide layer is SiO 2 , and the cleaned silicon substrate can be etched by the method of argon etching. The process conditions of argon etching in this embodiment include a pressure of 4.5×10 6 torr, a temperature of 380 °C, a filament current of 7 mA, a high-voltage energy of 480 eV, and a processing time of 20 min.

[0130] S23: After the argon etching is completed, raise the temperature in the MBE vacuum chamber to 500 °C and anneal the silicon substrate for 35 min to repair the surface lattice of the silicon substrate.

[0131] In this embodiment, argon etching is carried out in the MBE vacuum chamber to etch away the surface oxide layer, and then annealing is performed to flatten the surface and repair the lattice, further improving the surface flatness of the silicon substrate.

[0132] S3: Perform surface nitridation treatment on the silicon substrate to form a Si 3 N 4 layer on the surface of the silicon substrate.

[0133] The surface nitridation treatment includes the following steps:

[0134] S31: Place the silicon substrate in the vacuum chamber of the MBE, set the temperature to 420 °C, and introduce nitrogen with a flow rate of 0.9 sccm into the vacuum chamber; among them, the duration of nitrogen is 7 min.

[0135] S32: Treat the silicon substrate with nitrogen-containing plasma at a power of 220 W for 24 min.

[0136] S33: After the nitrogen-containing plasma treatment is completed, raise the temperature to 500 °C, anneal for 35 min, and then turn off the N 2 gas source and the nitrogen-containing plasma radio frequency source.

[0137] S34: Take out the nitrided silicon substrate after the temperature in the vacuum chamber drops to room temperature; among them, the nitrided silicon substrate has a Si 3 N 4 layer on at least one side surface.

[0138] S4: Grow a single-layer graphene layer on the copper foil.

[0139] 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:

[0140] S41: Place the copper foil in a quartz tube furnace at a temperature of 1000 °C, introduce hydrogen with a flow rate of 10 sccm into the quartz tube furnace, and anneal for 25 min;

[0141] S42: Under the condition of a pressure of 1 torr, introduce methane with a flow rate of 5 sccm and hydrogen with a flow rate of 50 sccm into the quartz tube furnace and maintain for 30 min to grow a single-layer graphene layer on the copper foil.

[0142] S5: Cover the surface of the silicon substrate with the Si 3 N 4 layer with the single-layer graphene layer.

[0143] After the growth of the single-layer graphene layer is completed, polymethyl methacrylate is used to adhere to the graphene to peel the single-layer graphene layer from the copper foil, and it is covered on the side surface of the silicon substrate with an Si 3 N 4 layer to form a single-layer graphene / Si 3 N 4 / Si structure.

[0144] S6: Remotely epitaxially grow a nitride film on the graphene layer, and the lattice information of the nitride film is the same as that of the Si 3 N 4 layer's lattice structure information.

[0145] In this embodiment, the material of the nitride film is gallium nitride, and the remote epitaxial nitride includes the following steps:

[0146] S61a: Under the condition of a temperature of 600 °C, introduce a nitrogen source with a flow rate of 8000 sccm, a gallium source with a flow rate of 30 sccm, and a carrier gas, and react for 30 min to grow a nucleation layer.

[0147] The gallium source is trimethylgallium, the nitrogen source is NH 3 , and the carrier gas is a mixed gas composed of nitrogen with a flow rate of 400 sccm and hydrogen with a flow rate of 40 sccm.

[0148] S62a: Under the condition of a temperature of 1000 °C, introduce a nitrogen source with a flow rate of 5000 sccm, a gallium source with a flow rate of 30 sccm, and a carrier gas, and react for 200 min to grow a gallium nitride film on the nucleation layer.

[0149] Example 4

[0150] The difference between this embodiment and Example 3 lies in the difference in step S6. In this embodiment, the nitride film is aluminum nitride, and the remote epitaxial nitride includes the following steps:

[0151] S61b: Under the condition of a temperature of 800 °C, introduce a nitrogen source with a flow rate of 8000 sccm, an aluminum source with a flow rate of 30 sccm, and a carrier gas, and react for 30 min to grow a nucleation layer;

[0152] The aluminum source is trimethylaluminum, the nitrogen source is NH 3 , and the carrier gas is a mixed gas composed of nitrogen with a flow rate of 400 sccm and hydrogen with a flow rate of 40 sccm.

[0153] S62b: Under the condition that the temperature is 1200 °C, introduce a nitrogen source with a flow rate of 5000 sccm, an aluminum source with a flow rate of 30 sccm, and a carrier gas, and react for 200 min to grow a thin film layer on the nucleation layer to obtain an aluminum nitride thin film.

[0154] Example 5

[0155] The method for remotely epitaxially growing a nitride thin film on a silicon substrate provided in this example specifically includes the following steps:

[0156] S1: Prepare a silicon substrate.

[0157] The silicon substrate in this example is a single-crystalline silicon substrate with a (100) plane.

[0158] S2: Perform surface treatment on the silicon substrate.

[0159] S21: Clean the surface of the silicon substrate.

[0160] First, ultrasonically clean in an acetone solution for 10 min, then ultrasonically clean in an isopropanol solution for 10 min, and finally ultrasonically clean in water for 10 min.

[0161] S22: Place the cleaned silicon substrate in an MBE vacuum chamber, introduce argon into the MBE vacuum chamber, and use argon to etch the oxide layer on the surface of the cleaned silicon substrate.

[0162] The material of the oxide layer is SiO 2 , and the cleaned silicon substrate can be etched by the method of argon etching. The process conditions of argon etching in this example include a pressure of 5.5×10 6 torr, a temperature of 420 °C, a filament current of 9 mA, a high-voltage energy of 520 eV, and a processing time of 10 min.

[0163] S23: After the argon etching is completed, raise the temperature in the MBE vacuum chamber to 650 °C and anneal the silicon substrate for 25 min to repair the surface lattice of the silicon substrate.

[0164] In this example, argon etching was carried out in the MBE vacuum chamber to etch away the surface oxide layer, and then annealing was performed to flatten the surface and repair the lattice, further improving the surface flatness of the silicon substrate.

[0165] S3: Perform surface nitridation treatment on the silicon substrate to form a Si 3 N 4 layer on the surface of the silicon substrate.

[0166] The surface nitridation treatment includes the following steps:

[0167] S31: Place the silicon substrate in the vacuum chamber of the MBE, set the temperature to 550 °C, and introduce nitrogen gas with a flow rate of 1.8 sccm into the vacuum chamber; wherein, the duration of the nitrogen gas is 4 min.

[0168] S32: Treat the silicon substrate with nitrogen-containing plasma at a power of 370 W for 10 min.

[0169] S33: After the treatment with nitrogen-containing plasma is completed, raise the temperature to 650 °C and anneal for 25 min, then turn off the N 2 gas source and the radio frequency source of the nitrogen-containing plasma.

[0170] S34: Take out the nitrided silicon substrate after the temperature in the vacuum chamber drops to room temperature; wherein, at least one surface of the nitrided silicon substrate has a Si 3 N 4 layer.

[0171] S4: Grow a single-layer graphene layer on the copper foil.

[0172] The material of the single-layer graphene layer can be single-crystal graphene or polycrystalline graphene; growing the single-layer graphene includes the following steps:

[0173] S41: Place the copper foil in a quartz tube furnace at a temperature of 1200 °C, introduce hydrogen gas with a flow rate of 15 sccm into the quartz tube furnace, and anneal for 10 min;

[0174] S42: Under the condition of a pressure of 3 torr, introduce methane with a flow rate of 10 sccm and hydrogen gas with a flow rate of 100 sccm into the quartz tube furnace, and maintain for 20 min to grow a single-layer graphene layer on the copper foil.

[0175] S5: Cover the single-layer graphene layer on the surface of the silicon substrate having a Si 3 N 4 layer.

[0176] After the growth of the single-layer graphene layer is completed, use polymethyl methacrylate to adhere to the graphene to peel the single-layer graphene layer from the copper foil, and cover it on the Si 3 N 4 layer / silicon substrate surface to form a single-layer graphene / Si 3 N 4 / Si structure.

[0177] S6: Remotely epitaxially grow a nitride thin film on the graphene layer, and the lattice information of the nitride thin film is the same as the lattice structure information of the silicon substrate.

[0178] In this embodiment, the material of the nitride thin film is gallium nitride, and the remote epitaxial nitride includes the following steps:

[0179] S61a: Under the condition that the temperature is 800 °C, introduce a nitrogen source with a flow rate of 14000 sccm, a gallium source with a flow rate of 80 sccm, and a carrier gas, and react for 5 min to grow a nucleation layer.

[0180] The gallium source is trimethylgallium, and the nitrogen source is NH 3 , and the carrier gas is a mixed gas composed of nitrogen with a flow rate of 600 sccm and hydrogen with a flow rate of 60 sccm.

[0181] S62a: Under the condition that the temperature is 1200 °C, introduce a nitrogen source with a flow rate of 8000 sccm, a gallium source with a flow rate of 90 sccm, and a carrier gas, and react for 150 min to grow a thin film layer on the nucleation layer to obtain a gallium nitride thin film.

[0182] Example 6

[0183] The difference between this example and Example 5 lies in the different steps of S6. The nitride thin film in this example is aluminum nitride, and the remote epitaxial nitride includes the following steps:

[0184] S61b: Under the condition that the temperature is 1100 °C, introduce a nitrogen source with a flow rate of 14000 sccm, an aluminum source with a flow rate of 80 sccm, and a carrier gas, and react for 5 min to grow a nucleation layer;

[0185] The aluminum source is trimethylaluminum, and the nitrogen source is NH 3 , and the carrier gas is a mixed gas composed of nitrogen with a flow rate of 600 sccm and hydrogen with a flow rate of 60 sccm.

[0186] S62b: Under the condition that the temperature is 1400 °C, introduce a nitrogen source with a flow rate of 8000 sccm, an aluminum source with a flow rate of 90 sccm, and a carrier gas, and react for 150 min to grow a thin film layer on the nucleation layer to obtain an aluminum nitride thin film.

[0187] The present invention uses the means of surface nitridation modification and the growth method of remote epitaxy to endow the silicon substrate that cannot be remotely epitaxied with the ability of remote epitaxy, that is, it can remotely epitaxially grow nitride thin films on the silicon substrate, while improving the quality of the epitaxial thin film, it can also achieve CMOS compatibility. Compared with the existing technology, the advantages of the present invention are:

[0188] 1) The single-layer graphene layer and the nitride thin film in the present invention are not bonded by covalent bonds, but by a weak electrostatic force between van der Waals forces and covalent bonds, so as to achieve the growth of a nitride thin film with almost no stress on the silicon substrate and improve the growth quality of the nitride thin film at the same time.

[0189] 2) There is a large thermal mismatch between the commonly used silicon substrate and the nitride thin film, and the quality of the epitaxial nitride thin film is poor, seriously affecting the performance and reliability of the device. Through the good thermal conductivity material of graphene, the present invention can relieve the thermal stress during the epitaxial process and improve the quality of the nitride thin film.

[0190] 3) It is difficult to strip the nitride thin film directly epitaxially grown on the silicon substrate, and the stripping operation is complex, resulting in a large number of defects and damages. The present invention grows the nitride thin film on the single-layer graphene layer, which can make the lattice structure information of the nitride thin film the same as that of the Si 3 N 4 layer on the surface of the silicon substrate, relieve the large lattice mismatch and thermal mismatch existing during the epitaxial growth of the nitride thin film on the silicon substrate, reduce the defects and stresses caused by the lattice mismatch and thermal mismatch. At the same time, the weak electrostatic force between the single-layer graphene layers helps the stripping of the nitride thin film, reducing the probability of defects and damages in the nitride thin film.

[0191] 4) The present invention directly modifies the surface of the silicon substrate with nitrogen plasma, which has simple operation and fewer steps, and is suitable for large-scale industrial promotion.

[0192] The above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and their purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

[0193] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

Claims

1. A method for remote epitaxial growth of a nitride film on a silicon substrate, characterized in that: The steps include: Performing a surface nitridation treatment on the silicon substrate to form a Si3N4 layer on the surface of the silicon substrate; Forming a single-layer graphene layer on a surface of the silicon substrate having the Si3N4 layer; remote epitaxially growing a nitride film on the single-layer graphene layer; Wherein, the lattice information of the nitride film is the same as the lattice structure information of the Si3N4 layer; The surface of the Si3N4 layer has potential fluctuations, which are used to make the termination surface of the silicon substrate present Si-N bonds with lattice periodicity, induce the redistribution of charges on the surface of the single-layer graphene layer, and realize the remote epitaxial nitride film on the silicon substrate.

2. 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 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.

3. The method according to claim 1, characterized in that The material of the nitride film is gallium nitride, and the remote epitaxial growth of the nitride film comprises the following steps: 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 a reaction time of 5-30 minutes to grow a nucleation layer; Under the condition of a temperature of 1000-1200° C., 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 are introduced, and the reaction is carried out for 150-200 minutes to grow a thin film layer on the nucleation layer to obtain the nitride thin film; Wherein, 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.

4. The method according to claim 1, characterized in that: The material of the nitride film is aluminum nitride, and the remote epitaxial growth of the nitride film comprises the following steps: 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 time is 5-30 minutes to grow a nucleation layer; Under the condition of temperature of 1200-1400° C., a nitrogen source with a flow rate of 5000-8000 sccm, an aluminum source with a flow rate of 30-90 sccm 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 the nitride thin film; Wherein, 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.

5. The method according to claim 1, characterized in that The silicon substrate is a single crystal silicon substrate with a (100) plane; And / or, before the surface nitridation treatment of the silicon substrate is performed, the following steps are included: Cleaning the surface of the silicon substrate; The cleaned silicon substrate is placed in an MBE vacuum chamber, argon gas is introduced into the MBE vacuum chamber, and the oxide layer on the surface of the cleaned silicon substrate is etched using the argon gas.

6. The method according to claim 5, characterized in that The process conditions of the argon etching include a pressure of 4.5-5.5×10 6 torr, temperature is 380-420°C, filament current is 7-9mA, high voltage energy is 480-520eV and processing time is 10-20min.

7. 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 onto the surface of the silicon substrate having the Si3N4 layer by wet transfer.

8. The method according to claim 7, 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 annealing is performed for 10-25 minutes; Under the condition of 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.

9. A nitride thin film, characterized in that: The nitride film is prepared by the method according to any one of claims 1 to 8.

10. A semiconductor device, characterized in that: Comprising the nitride thin film as claimed in claim 9.

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