Silicon carbide-two-dimensional diamond composite wafer and preparation method and application thereof

Abstract

The present application relates to a kind of silicon carbide-two-dimensional diamond composite wafer and its preparation method and application.The silicon carbide-two-dimensional diamond composite wafer includes silicon carbide, and two-dimensional diamond film and two-dimensional diamond single crystal sequentially stacked on the surface of the silicon carbide;Wherein, the thickness ratio of the silicon carbide and the two-dimensional diamond single crystal is 1:2-1:20.The silicon carbide-two-dimensional diamond composite wafer has large size, high quality at the same time, and is not easy to break during processing, and the thermal conductivity is high, can be used as high thermal conductivity substrate or packaging heat sink material, for preparing large size microwave device.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and in particular to a silicon carbide-two-dimensional diamond composite wafer, its preparation method, and its application. Background Technology

[0002] Currently, high-power gallium nitride (GaN) devices generally use silicon carbide substrates. However, with the further increase in power density of high-power gallium nitride devices, silicon carbide substrates with a thermal conductivity of 390 W / m·K are insufficient to meet the heat dissipation requirements of high-power gallium nitride devices, and there is an urgent need to use substrate materials with higher thermal conductivity.

[0003] Diamond boasts a thermal conductivity as high as 2000 W / m·K, second only to graphene in thermal conductivity among naturally occurring materials. Therefore, diamond is increasingly becoming the preferred packaging material for high-power gallium nitride (GaN) devices. However, directly growing three-dimensional diamond single crystals on silicon carbide (SiC) is challenging, and these crystals are prone to detachment and wafer fragmentation during fabrication. These factors represent significant technical difficulties hindering the application of SiC-3D diamond single-crystal composite wafers. In contrast, fabricating low-dimensional diamond on SiC is much easier.

[0004] In traditional techniques, low-dimensional diamond films can be directly deposited on silicon substrates by adjusting process parameters. However, due to lattice mismatch between diamond and silicon, interfacial stress is introduced into the composite wafer. Although introducing a silicon nitride buffer layer or a graphene buffer layer directly between the diamond and silicon substrate to prepare two-dimensional diamond can reduce interfacial stress to some extent, it is difficult to prepare large-size, high-quality two-dimensional diamond based on the buffer layer. This means that the composite wafer still suffers from problems such as fragility during processing and cannot overcome the challenges of large-size microwave devices. Summary of the Invention

[0005] Based on this, it is necessary to provide a silicon carbide-two-dimensional diamond composite wafer, its preparation method, and its application to address the above problems. The silicon carbide-two-dimensional diamond composite wafer has large size and high quality, is not easily broken during processing, and has high thermal conductivity, so it can be used as a high thermal conductivity substrate or packaging heat sink material for the preparation of large-size microwave devices.

[0006] A silicon carbide-two-dimensional diamond composite wafer includes silicon carbide, and a two-dimensional diamond film and a two-dimensional diamond single crystal sequentially stacked on the surface of the silicon carbide.

[0007] The thickness ratio of the silicon carbide to the two-dimensional diamond single crystal is 1:2 to 1:20.

[0008] In one embodiment, the thickness ratio of the silicon carbide to the two-dimensional diamond single crystal is 1:2 to 1:10.

[0009] In one embodiment, the thickness of the two-dimensional diamond single crystal is 100μm-500μm;

[0010] And / or, the thickness of the silicon carbide is 30μm-50μm.

[0011] In one embodiment, the flatness of the two-dimensional diamond single crystal is 3nm-10nm;

[0012] And / or, the flatness of the two-dimensional diamond film is 3nm-10nm.

[0013] A method for preparing a silicon carbide-two-dimensional diamond composite wafer as described above includes the following steps:

[0014] A silicon carbide substrate is provided, and a graphite layer is deposited on the silicon surface of the silicon carbide substrate in a mixed atmosphere of protective gas and reactive gas, or a graphite layer is formed by pyrolysis on the carbon surface of the silicon carbide substrate.

[0015] The graphite layer is pyrolyzed in a mixed atmosphere of protective gas and reactive gas to obtain a graphene layer.

[0016] The graphene layer was subjected to high-pressure pyrolysis to obtain a two-dimensional diamond film.

[0017] Two-dimensional diamond single crystals are epitaxially deposited on the surface of the two-dimensional diamond film;

[0018] The silicon carbide substrate is thinned to obtain a silicon carbide-two-dimensional diamond composite wafer.

[0019] In one embodiment, the thickness of the silicon carbide substrate is 400 μm-600 μm.

[0020] In one embodiment, the reactant gas is selected from H2.

[0021] In one embodiment, in the step of pyrolyzing the carbon surface of the silicon carbide substrate to form a graphite layer, the pyrolysis temperature is 2000℃-2500℃.

[0022] And / or, in the step of pyrolyzing the graphite layer, the pyrolysis temperature is 800℃-1500℃;

[0023] And / or, in the high-pressure pyrolysis step, the temperature is 800℃-1000℃ and the pressure is 3kPa-5kPa.

[0024] In one embodiment, the method for surface epitaxial deposition of two-dimensional diamond single crystals on the surface of the two-dimensional diamond film is selected from hot-filament chemical vapor deposition.

[0025] A silicon carbide-two-dimensional diamond composite wafer as described above is used to fabricate gallium nitride high electron mobility transistor microwave devices.

[0026] In the silicon carbide-two-dimensional diamond composite wafer described in this invention, a two-dimensional diamond film is used as a buffer layer to construct a composite structure with a thick two-dimensional diamond single crystal as the main substrate and an ultra-thin silicon carbide as the auxiliary substrate. On the one hand, this overcomes the problems of low thermal conductivity and insufficient heat dissipation capacity of silicon carbide wafer substrates in traditional technologies, giving the silicon carbide-two-dimensional diamond composite wafer high thermal conductivity, corrosion resistance, and oxidation resistance. On the other hand, it not only reduces the interfacial stress caused by lattice mismatch between the two-dimensional diamond single crystal and silicon carbide, enhancing the lateral bonding force of the silicon carbide-two-dimensional diamond composite wafer, but also provides more effective support through high-quality two-dimensional diamond single crystals. This is beneficial for improving the size and quality of the silicon carbide-two-dimensional diamond composite wafer while making it less prone to breakage during processing.

[0027] Therefore, the silicon carbide-two-dimensional diamond composite wafer described in this invention can be used as a high thermal conductivity substrate or packaging heat sink material, which not only helps to improve the heat dissipation effect of semiconductor transistors, but can also be used to prepare large-size microwave devices, especially suitable for preparing gallium nitride high electron mobility transistor microwave devices. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a silicon carbide-two-dimensional diamond composite wafer according to one embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the process for preparing a silicon carbide-two-dimensional diamond composite wafer according to one embodiment of the present invention.

[0030] Among them, 101 is silicon carbide; 102 is a two-dimensional diamond film; 103 is a two-dimensional diamond single crystal; 104 is a graphite layer; and 105 is a graphene layer. Detailed Implementation

[0031] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments or examples only and is not intended to be limiting of the invention.

[0033] like Figure 1 The diagram shows a silicon carbide-two-dimensional diamond composite wafer provided by the present invention. The silicon carbide-two-dimensional diamond composite wafer includes silicon carbide 101, and two-dimensional diamond film 102 and two-dimensional diamond single crystal 103 sequentially stacked on the surface of silicon carbide 101.

[0034] The thickness ratio of the silicon carbide 101 to the two-dimensional diamond single crystal 103 is 1:2 to 1:20.

[0035] Compared with traditional silicon carbide composite wafers with silicon carbide as the substrate and ultrathin thermally conductive composite materials, the silicon carbide-two-dimensional diamond composite wafer provided by this invention uses a two-dimensional diamond film 102 as a buffer layer to construct a composite structure with a thick two-dimensional diamond single crystal 103 as the main substrate and an ultrathin silicon carbide 101 as the auxiliary substrate. On the one hand, it overcomes the problems of low thermal conductivity and insufficient heat dissipation capacity of silicon carbide wafer substrates in traditional technologies, giving the silicon carbide-two-dimensional diamond composite wafer high thermal conductivity, corrosion resistance, and oxidation resistance. On the other hand, it not only reduces the interfacial stress caused by lattice mismatch between the two-dimensional diamond single crystal 103 and silicon carbide 101, enhancing the lateral bonding force of the silicon carbide-two-dimensional diamond composite wafer, but also provides more effective support due to the high-quality two-dimensional diamond single crystal 103. This is beneficial for improving the size and quality of the silicon carbide-two-dimensional diamond composite wafer while making it less prone to breakage during processing.

[0036] In order to further synergistically regulate the thermal conductivity and supporting effect of silicon carbide-two-dimensional diamond composite wafers and optimize the overall performance of silicon carbide-two-dimensional diamond composite wafers, preferably, the thickness ratio of silicon carbide 101 to two-dimensional diamond single crystal 103 is 1:2-1:10.

[0037] Specifically, the thickness of the two-dimensional diamond single crystal 103 is 100μm-500μm, preferably 100μm-300μm;

[0038] And / or, the thickness of silicon carbide 101 is 30μm-50μm.

[0039] Considering that the higher the density of the two-dimensional diamond single crystal 103, the better the quality of the two-dimensional diamond single crystal 103, which is beneficial to further improve the size, quality and corrosion resistance of the silicon carbide-two-dimensional diamond composite wafer, preferably, the flatness of the two-dimensional diamond single crystal 103 is 3nm-10nm, and more preferably 3nm-5nm.

[0040] In order to synergistically improve the flatness of the two-dimensional diamond single crystal 103, preferably, the flatness of the two-dimensional diamond film 102 is 3nm-10nm, and more preferably 3nm-5nm.

[0041] Based on two-dimensional diamond single crystal 103 as the main substrate, it has excellent support. The diameter of silicon carbide 101 can preferably be 2 inches, 4 inches, 6 inches or 8 inches. This invention does not limit this, and those skilled in the art can choose according to actual preparation needs.

[0042] The performance selection of silicon carbide 101 in silicon carbide-two-dimensional diamond composite wafers varies depending on the product requirements of different types of semiconductor devices.

[0043] In one embodiment, when using a silicon carbide-two-dimensional diamond composite wafer to fabricate a gallium nitride high electron mobility transistor (HEMT) microwave device, a resistivity greater than 10 is preferred. 5 Semi-insulating silicon carbide 101 with Ω·cm.

[0044] like Figure 2 The diagram shown is a schematic flow chart of a method for preparing a silicon carbide-two-dimensional diamond composite wafer provided by the present invention, including the following steps:

[0045] S1, a silicon carbide substrate is provided, and a graphite layer is deposited on the silicon surface of the silicon carbide substrate in a mixed atmosphere of protective gas and reactive gas, or a graphite layer is formed by pyrolysis on the carbon surface of the silicon carbide substrate.

[0046] S2, In a mixed atmosphere of protective gas and reactive gas, the graphite layer is pyrolyzed to obtain a graphene layer;

[0047] S3, the graphene layer is subjected to high-pressure pyrolysis to obtain a two-dimensional diamond film;

[0048] S4, a two-dimensional diamond single crystal is epitaxially deposited on the surface of the two-dimensional diamond film;

[0049] S5, the silicon carbide substrate is thinned to obtain a silicon carbide-two-dimensional diamond composite wafer.

[0050] In step S1, in order to ensure the preparation of high-quality two-dimensional diamond film 102 and two-dimensional diamond single crystal 103 in subsequent steps, the thickness of silicon carbide substrate 101 is preferably 400μm-600μm.

[0051] To enhance the lateral bonding force between silicon carbide 101 and two-dimensional diamond single crystal 103, a buffer layer is added between silicon carbide 101 and two-dimensional diamond single crystal 103.

[0052] Based on the unique silicon and carbon surfaces of the silicon carbide 101 substrate, the formation of a graphite layer 104 buffer layer on the surface of the silicon carbide 101 substrate can be categorized into the following two cases:

[0053] In one embodiment, a graphite layer 104 is deposited directly on the silicon surface of the silicon carbide 101 substrate to form Si-C bonds, thereby improving the lateral bonding force between the silicon carbide 101 substrate and the graphite layer 104.

[0054] Specifically, using magnetron sputtering, a graphite target is used as the sputtering carbon source, and Ar and O2 with a volume ratio of 9:1 to 7:1 are introduced into the sputtering cavity as sputtering gases. Under the condition of working power of 20W-100W, a graphite layer 104 is formed on the silicon surface of a silicon carbide 101 substrate by magnetron sputtering.

[0055] In another embodiment, a graphite layer 104 is formed by the pyrolytic transformation of the carbon surface of the silicon carbide 101 substrate, which does not require an additional load and avoids the generation of interfacial stress.

[0056] Specifically, in the step of pyrolyzing the carbon surface of the silicon carbide substrate to form a graphite layer, the pyrolysis temperature is 2000℃-2500℃.

[0057] To promote the phase transition from graphene to two-dimensional diamond and increase the stability of two-dimensional diamond, surface terminal functionalization (hydrogenation, chlorination, fluorination) is required. A reaction gas is introduced into the reaction chamber, preferably H2.

[0058] In step S2, compared with the traditional technique of generating graphene layer by pyrolysis of silicon carbide in one step, the present invention adopts a two-step method. First, a graphite layer 104 is formed on the surface of silicon carbide, and then the graphite layer 104 is pyrolyzed to transform it into a large-area, high-quality graphene layer 105, which is beneficial to improving the size and quality of silicon carbide-two-dimensional diamond composite wafer.

[0059] In one embodiment, a silicon carbide 101 substrate with a graphite layer 104 is placed on a support of a CVD tube furnace with the graphite layer 104 facing upwards. Ar is introduced as a protective gas and H2 is introduced as a reaction gas. The tube furnace is first heated to 800°C-1000°C and held for 10-20 minutes. Then, the temperature is increased to 1400°C-1500°C and held for 20-30 minutes to complete the growth of the graphene layer 105.

[0060] In step S3, in order to further improve the density of the graphene layer 105 in the formation of the two-dimensional diamond film 102, it is preferable to allow the graphene layer 105 to adsorb at least one of H, H2, F, F2, H2O and NH3 under high temperature of 800℃-1000℃ and high pressure of 3kPa-5kPa, so as to induce a phase transition under high pressure, so that the surface chemical bonds are transformed from sp2 to sp3, and a dense, high-quality two-dimensional diamond film 102 is formed.

[0061] In step S4, based on the silicon carbide 101 substrate having a large area and high quality two-dimensional diamond film 102, homogeneous epitaxy is further performed on the surface of the two-dimensional diamond film 102 to obtain a two-dimensional diamond single crystal 103 with strong lateral bonding, high thermal conductivity, controllable thickness and good continuity.

[0062] To further improve the quality of the two-dimensional diamond single crystal 103, preferably, the method for epitaxially depositing the two-dimensional diamond single crystal on the surface of the two-dimensional diamond thin film 102 is selected from hot filament chemical vapor deposition (HFCVD).

[0063] In step S5, based on the fact that the two-dimensional diamond single crystal 103 has a certain thickness and density, and has a specific thickness ratio with the silicon carbide 101 substrate, it can replace the silicon carbide 101 as the main substrate to achieve the supporting function, so that the silicon carbide-two-dimensional diamond composite wafer is not easy to break during processing. At the same time, in order to meet certain thickness conditions and make the silicon carbide-two-dimensional diamond composite wafer suitable for semiconductor devices, the 400μm-600μm silicon carbide 101 substrate is thinned, preferably the thickness of the thinned silicon carbide 101 is 30μm-50μm.

[0064] To meet the product fabrication requirements of HEMT devices, it is preferable to further polish the thinned silicon carbide 101 surface to achieve a surface flatness of 3nm-10nm.

[0065] A silicon carbide-two-dimensional diamond composite wafer as described above is used to fabricate gallium nitride high electron mobility transistor microwave devices.

[0066] The silicon carbide-two-dimensional diamond composite wafer described in this invention can be used as a high thermal conductivity substrate or packaging heat sink material, which not only helps to improve the heat dissipation effect of semiconductor transistors, but can also be used to prepare large-size microwave devices, especially suitable for preparing gallium nitride high electron mobility transistor microwave devices.

[0067] The following specific embodiments will further illustrate the silicon carbide-two-dimensional diamond composite wafer, its preparation method, and its applications.

[0068] Example 1

[0069] A silicon carbide substrate with a diameter of 2 inches and a thickness of 600 μm was selected. A graphite target was used as the sputtering carbon source by magnetron sputtering. Ar and O2 with a volume ratio of 9:1 were introduced into the sputtering cavity. Under the condition of working power of 50W, a graphite layer was formed on the silicon surface of the silicon carbide substrate by magnetron sputtering.

[0070] A silicon carbide substrate with a graphite layer is placed on a support of a CVD tube furnace with the graphite layer facing upwards. Ar is introduced as a protective gas and H2 is introduced as a reaction gas. The tube furnace is first heated to 800°C and held for 10 minutes, then the temperature is increased to 1400°C and held for 20 minutes to complete the growth of the graphene layer.

[0071] Under high temperature of 800℃ and high pressure of 3kPa, the graphene layer adsorbs H2 and undergoes a hydrogenation reaction on the surface, inducing a phase transition in the graphene to form a two-dimensional diamond film. The flatness of the two-dimensional diamond film is 3nm.

[0072] Two-dimensional diamond single crystals were homoepitaxially deposited on the surface of a two-dimensional diamond film using the HFCVD process. The thickness of the two-dimensional diamond single crystal was 100 μm and the flatness was 3 nm.

[0073] A silicon carbide substrate with a thickness of 600 μm was thinned to 50 μm, and the thinned silicon carbide surface was polished to achieve a surface flatness of 4 nm, thus obtaining a silicon carbide-two-dimensional diamond composite wafer.

[0074] Example 2

[0075] A silicon carbide substrate with a diameter of 4 inches and a thickness of 500 μm was selected. The silicon carbide carbon surface was pyrolyzed at a high temperature of 2000℃ and above in a quartz tube furnace under the protection of nitrogen gas. The carbon atoms on the silicon carbide carbon surface were reconstructed to generate a graphite layer with a multilayer structure.

[0076] A silicon carbide substrate with a graphite layer is placed on a support of a CVD tube furnace with the graphite layer facing upwards. Argon is introduced as a protective gas and hydrogen is introduced as a reaction gas. The tube furnace is first heated to 850°C and held for 15 minutes. Then the temperature is increased to 1450°C and held for 25 minutes to complete the growth of the graphene layer.

[0077] Under high temperature of 900℃ and high pressure of 3kPa-5kPa, graphene layers are converted by adsorption of F2 to form a two-dimensional diamond film, wherein the flatness of the two-dimensional diamond film is 5nm.

[0078] Two-dimensional diamond single crystals were homoepitaxially deposited on the surface of a two-dimensional diamond film using the HFCVD process. The thickness of the two-dimensional diamond single crystal was 300 μm and the flatness was 4 nm.

[0079] A silicon carbide substrate with a thickness of 500 μm was thinned to 40 μm, and the thinned silicon carbide surface was polished to achieve a surface flatness of 6 nm, thus obtaining a silicon carbide-two-dimensional diamond composite wafer.

[0080] Example 3

[0081] A silicon carbide substrate with a diameter of 6 inches and a thickness of 500 μm was selected. A graphite target was used as the sputtering carbon source by magnetron sputtering. Ar and O2 with a volume ratio of 9:1 were introduced into the sputtering cavity. Under the condition of working power of 50W, a graphite layer was formed on the silicon surface of the silicon carbide substrate by magnetron sputtering.

[0082] A silicon carbide substrate with a graphite layer is placed on a support of a CVD tube furnace with the graphite layer facing upwards. Argon gas is introduced as a protective gas and hydrogen gas is introduced as a reaction gas. The tube furnace is first heated to 900°C and held for 15 minutes. Then the temperature is increased to 1450°C and held for 25 minutes to complete the growth of the graphene layer.

[0083] Under high temperature of 900℃ and high pressure of 4kPa, H atoms are adsorbed on the graphene layer to form a two-dimensional diamond film, wherein the flatness of the two-dimensional diamond film is 8nm.

[0084] Two-dimensional diamond single crystals were homoepitaxially deposited on the surface of a two-dimensional diamond film using the HFCVD process. The thickness of the two-dimensional diamond single crystal was 300 μm and the flatness was 6 nm.

[0085] A silicon carbide substrate with a thickness of 500 μm was thinned by 30 μm, and the thinned silicon carbide surface was polished to achieve a surface flatness of 6 nm, thus obtaining a silicon carbide-two-dimensional diamond composite wafer.

[0086] Example 4

[0087] A silicon carbide substrate with a diameter of 8 inches and a thickness of 400 μm was selected. The silicon carbide carbon surface was pyrolyzed at a high temperature of 2000℃ and above in a quartz tube furnace under the protection of nitrogen gas. The carbon atoms on the silicon carbide carbon surface were reconstructed to generate a graphite layer with a multilayer structure.

[0088] A silicon carbide substrate with a graphite layer is placed on a support of a CVD tube furnace with the graphite layer facing upwards. Argon is introduced as a protective gas and hydrogen is introduced as a reaction gas. The tube furnace is first heated to 1000℃ and held for 20 minutes, then the temperature is increased to 1500℃ and held for 30 minutes to complete the growth of the graphene layer.

[0089] Under high temperature of 1000℃ and high pressure of 5kPa, a graphene layer is subjected to adsorption of NH3 to form a two-dimensional diamond film, wherein the flatness of the two-dimensional diamond film is 10nm.

[0090] Two-dimensional diamond single crystals were homoepitaxially deposited on the surface of a two-dimensional diamond film using the HFCVD process. The thickness of the two-dimensional diamond single crystal was 500 μm and the flatness was 10 nm.

[0091] A silicon carbide substrate with a thickness of 400 μm was thinned by 25 μm, and the thinned silicon carbide surface was polished to achieve a surface flatness of 9 nm, thus obtaining a silicon carbide-two-dimensional diamond composite wafer.

[0092] Comparative Example 1

[0093] A silicon carbide substrate with a diameter of 4 inches and a thickness of 500 μm was selected. The silicon carbide carbon surface was pyrolyzed at a high temperature of 2000℃ and above in a quartz tube furnace under the protection of nitrogen gas. The carbon atoms on the silicon carbide carbon surface were reconstructed to generate a graphite layer with a multilayer structure.

[0094] A silicon carbide substrate with a graphite layer is placed on a support of a CVD tube furnace with the graphite layer facing upwards. Argon is introduced as a protective gas and hydrogen is introduced as a reaction gas. The tube furnace is first heated to 850°C and held for 15 minutes. Then the temperature is increased to 1450°C and held for 25 minutes to complete the growth of the graphene layer.

[0095] Using the HFCVD process, two-dimensional diamond single crystals were homoepitaxially deposited on the surface of a graphene layer to obtain a silicon carbide-two-dimensional diamond composite wafer, wherein the thickness of the two-dimensional diamond single crystal was 50 μm and the flatness was 16 nm.

[0096] Comparative Example 2

[0097] A silicon carbide substrate with a diameter of 4 inches and a thickness of 500 μm was selected. The silicon carbide carbon surface was pyrolyzed at a high temperature of 2000℃ and above in a quartz tube furnace under the protection of nitrogen gas. The carbon atoms on the silicon carbide carbon surface were reconstructed to generate a graphite layer with a multilayer structure.

[0098] A silicon carbide substrate with a graphite layer is placed on a support of a CVD tube furnace with the graphite layer facing upwards. Argon is introduced as a protective gas and hydrogen is introduced as a reaction gas. The tube furnace is first heated to 850°C and held for 15 minutes. Then the temperature is increased to 1450°C and held for 25 minutes to complete the growth of the graphene layer.

[0099] Under high temperature of 900℃ and high pressure of 3kPa-5kPa, the graphene layer is converted to adsorb F2 to form a two-dimensional diamond film, resulting in a silicon carbide-two-dimensional diamond composite wafer. The flatness of the two-dimensional diamond film is 5nm.

[0100] Comparative Example 3

[0101] A silicon carbide substrate with a diameter of 4 inches and a thickness of 500 μm was selected. The silicon carbide carbon surface was pyrolyzed at a high temperature of 2000℃ and above in a quartz tube furnace under the protection of nitrogen gas. The carbon atoms on the silicon carbide carbon surface were reconstructed to generate a graphite layer with a multilayer structure.

[0102] A silicon carbide substrate with a graphite layer is placed on a support of a CVD tube furnace with the graphite layer facing upwards. Argon is introduced as a protective gas and hydrogen is introduced as a reaction gas. The tube furnace is first heated to 850°C and held for 15 minutes. Then the temperature is increased to 1450°C and held for 25 minutes to complete the growth of the graphene layer.

[0103] Under high temperature of 900℃ and high pressure of 3kPa-5kPa, graphene layers are converted by adsorption of F2 to form a two-dimensional diamond film, wherein the flatness of the two-dimensional diamond film is 5nm.

[0104] Using the HFCVD process, a two-dimensional diamond single crystal was homoepitaxially deposited on the surface of a two-dimensional diamond film to obtain a silicon carbide-two-dimensional diamond composite wafer, wherein the thickness of the two-dimensional diamond single crystal was 50 μm and the flatness was 2 nm.

[0105] Comparative Example 4

[0106] The difference between Comparative Example 4 and Example 2 is that the silicon carbide substrate with a thickness of 500 μm was thinned to 12 μm.

[0107] The silicon carbide-two-dimensional diamond composite wafers prepared in Examples 1-4 and Comparative Examples 1-4 were subjected to performance tests, and the results are shown in Table 1. The compressive strength was tested using the K-standard compressive strength test; the tensile strength was tested using a universal testing machine; the thermal conductivity was tested using thermal conductivity testing; the corrosion resistance was tested using a salt spray test; and the oxidation resistance was tested using an aging test.

[0108] Table 1

[0109]

[0110] As shown in Table 1, the present invention constructs a silicon carbide-two-dimensional diamond composite wafer with a two-dimensional diamond thin film as a buffer layer, a two-dimensional diamond single crystal as the main substrate, and an ultrathin silicon carbide as the auxiliary substrate. While having large size and high quality, it also has high tensile strength and compressive strength, making it less prone to breakage during processing. In addition, it has high thermal conductivity, strong corrosion resistance and oxidation resistance, and can be used to prepare large-size microwave devices with excellent performance.

[0111] Example 5

[0112] The difference between Example 5 and Example 2 is that the thickness of the epitaxially deposited two-dimensional diamond single crystal is 200 μm.

[0113] Example 6

[0114] The difference between Example 6 and Example 2 is that the thickness of the epitaxially deposited two-dimensional diamond single crystal is 400 μm.

[0115] Example 7

[0116] The difference between Example 7 and Example 2 is that the thickness of the epitaxially deposited two-dimensional diamond single crystal is 480 μm.

[0117] Example 8

[0118] The difference between Example 8 and Example 2 is that the thickness of the epitaxially deposited two-dimensional diamond single crystal is 600 μm.

[0119] The silicon carbide-two-dimensional diamond composite wafers prepared in Examples 5-8 were subjected to performance tests, and the results are shown in Table 2.

[0120] Table 2

[0121]

[0122] Comparing Examples 2 and 5-8, it can be seen that when the thickness ratio of silicon carbide to two-dimensional diamond single crystal is 1:2-1:10, the mechanical properties of the silicon carbide-two-dimensional diamond composite wafer are better.

[0123] Example 9

[0124] The difference between Example 9 and Example 2 is that the flatness of the two-dimensional diamond single crystal is 8 nm.

[0125] Example 10

[0126] The difference between Example 10 and Example 2 is that the flatness of the two-dimensional diamond single crystal is 12nm.

[0127] The silicon carbide-two-dimensional diamond composite wafers prepared in Examples 9 and 10 were subjected to performance tests, and the results are shown in Table 3.

[0128] Table 3

[0129]

[0130] Comparing Examples 2, 9 and 10, it can be seen that when the flatness of the two-dimensional diamond single crystal is 3nm-10nm, the silicon carbide-two-dimensional diamond composite wafer has better corrosion resistance and oxidation resistance.

[0131] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0132] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A silicon carbide-two-dimensional diamond composite wafer, characterized in that, The silicon carbide-two-dimensional diamond composite wafer includes silicon carbide, and a two-dimensional diamond film and a two-dimensional diamond single crystal sequentially stacked on the surface of the silicon carbide. The thickness ratio of the silicon carbide to the two-dimensional diamond single crystal is 1:2 to 1:

20. The method for preparing the silicon carbide-two-dimensional diamond composite wafer includes the following steps: A silicon carbide substrate is provided, and a graphite layer is deposited on the silicon surface of the silicon carbide substrate in a mixed atmosphere of protective gas and reactive gas, or a graphite layer is formed by pyrolysis on the carbon surface of the silicon carbide substrate. The graphite layer is pyrolyzed in a mixed atmosphere of protective gas and reactive gas to obtain a graphene layer. The graphene layer was subjected to high-pressure pyrolysis to obtain a two-dimensional diamond film. Two-dimensional diamond single crystals are epitaxially deposited on the surface of the two-dimensional diamond film; The silicon carbide substrate is thinned to obtain a silicon carbide-two-dimensional diamond composite wafer.

2. The silicon carbide-two-dimensional diamond composite wafer according to claim 1, characterized in that, The thickness ratio of the silicon carbide to the two-dimensional diamond single crystal is 1:2 to 1:

10.

3. The silicon carbide-two-dimensional diamond composite wafer according to claim 1, characterized in that, The thickness of the two-dimensional diamond single crystal is 100μm-500μm; And / or, the thickness of the silicon carbide is 30μm-50μm.

4. The silicon carbide-two-dimensional diamond composite wafer according to claim 1, characterized in that, The flatness of the two-dimensional diamond single crystal is 3nm-10nm; And / or, the flatness of the two-dimensional diamond film is 3nm-10nm.

5. A method for preparing a silicon carbide-two-dimensional diamond composite wafer as described in any one of claims 1-4, characterized in that, Includes the following steps: A silicon carbide substrate is provided, and a graphite layer is deposited on the silicon surface of the silicon carbide substrate in a mixed atmosphere of protective gas and reactive gas, or a graphite layer is formed by pyrolysis on the carbon surface of the silicon carbide substrate. The graphite layer is pyrolyzed in a mixed atmosphere of protective gas and reactive gas to obtain a graphene layer. The graphene layer was subjected to high-pressure pyrolysis to obtain a two-dimensional diamond film. Two-dimensional diamond single crystals are epitaxially deposited on the surface of the two-dimensional diamond film; The silicon carbide substrate is thinned to obtain a silicon carbide-two-dimensional diamond composite wafer.

6. The method for preparing a silicon carbide-two-dimensional diamond composite wafer according to claim 5, characterized in that, The thickness of the silicon carbide substrate is 400μm-600μm.

7. The method for preparing a silicon carbide-two-dimensional diamond composite wafer according to claim 5, characterized in that, The reacting gas is selected from H2.

8. The method for preparing a silicon carbide-two-dimensional diamond composite wafer according to claim 5, characterized in that, In the step of pyrolyzing the carbon surface of the silicon carbide substrate to form a graphite layer, the pyrolysis temperature is 2000℃-2500℃. And / or, in the step of pyrolyzing the graphite layer, the pyrolysis temperature is 800℃-1500℃; And / or, in the high-pressure pyrolysis step, the temperature is 800℃-1000℃ and the pressure is 3kPa-5kPa.

9. The method for preparing a silicon carbide-two-dimensional diamond composite wafer according to claim 5, characterized in that, The method for surface epitaxial deposition of two-dimensional diamond single crystals on the two-dimensional diamond thin film is selected from hot-filament chemical vapor deposition.

10. A silicon carbide-two-dimensional diamond composite wafer as described in any one of claims 1-4 for fabricating gallium nitride high electron mobility transistor microwave devices.

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