Diamond substrate and manufacturing method of diamond substrate

Abstract

To provide an inexpensive and a large-diameter diamond substrate.SOLUTION: A diamond substrate 100 includes a substrate 1, a 3C-SiC layer 3 grown on the substrate 1 and a single crystal diamond layer 4 grown on the 3C-SiC layer 3. In a substrate side of a boundary surface between the substrate 1 and the 3C-SiC layer 3, a vacancy with a density of more than 0.001 and 10 or more pieces / μm2 is formed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a diamond substrate and a method for manufacturing a diamond substrate. [Background technology]

[0002] Diamond has excellent physical properties such as high hardness, good thermal conductivity, high carrier mobility, and a wide band gap, and is therefore expected to be applied to various semiconductor elements and electronic devices. Artificially synthesized diamond is used for these semiconductor elements and electronic devices. There are two methods for diamond synthesis: growth using ultra-high pressure and vapor phase growth. For semiconductor applications, vapor phase growth (CVD growth) has attracted attention because it can produce large-diameter substrates (e.g., Patent Documents 1 to 3).

[0003] As an example of a method for obtaining a large diameter substrate, as described in Non-Patent Document 1, there is a direct wafering method in which diamond substrates are combined and enlarged while growing the sidewalls, and a mosaic method in which small single crystal diamond substrates of a few millimeters square are laid out and grown by CVD. These methods aim to obtain a large diameter substrate from single crystal diamond by homoepitaxial growth. Since it starts with diamonds of a few millimeters square, it takes time to increase the diameter.

[0004] Patent Document 4 discloses a method of growing microneedles on a diamond substrate and then growing diamond on the microneedles. The microneedles prevent the wafer from being damaged.

[0005] On the other hand, methods for heteroepitaxial growth on substrates other than diamond are also being actively researched. As an example, Patent Document 5 discloses a step-flow growth method for heteroepitaxial growth on a substrate with an off-angle such as sapphire. This method has the advantage that diamond peels off from the substrate as it grows.

[0006] As another technique, Patent Document 6 describes a method for manufacturing a single crystal diamond substrate having a diameter of 100 mm or more and 300 mm or less, which includes the steps of preparing a cubic or hexagonal semiconductor single crystal other than diamond, dividing the semiconductor seed substrate into a plurality of child substrates, forming diamond nuclei on each of the divided child substrates, arranging the child substrates in the same arrangement as before division so that the gap between the child substrates is 20 μm or less to form base substrates, forming a single crystal diamond layer on the base substrate, and separating at least a portion of the single crystal diamond layer from the base substrate.

[0007] Furthermore, Patent Document 7 describes a method for forming a single crystal diamond film, which comprises preparing a single crystal silicon substrate with a (100) or (111) surface orientation, converting a 3C-SiC single crystal film into diamond nuclei by microwave plasma CVD in a carbon-containing atmosphere, and growing a single crystal diamond film on the single crystal silicon substrate by microwave plasma CVD. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2001-354491 A [Patent Document 2] JP 2004-176132 A [Patent Document 3] JP 2006-143561 A [Patent Document 4] JP 2018-58743 A [Patent Document 5] International Publication No. 2022 / 138788 [Patent Document 6] JP 2022-168623 A [Patent Document 7] JP 2023-082528 A [Non-patent literature]

[0009] [Non-Patent Document 1] Chayahara et al., "Large-scale and wafer-making technology using microwave plasma CVD," Synthesiology, Vol. 3, No. 4 (2010), p. 272. Summary of the Invention [Problem to be solved by the invention]

[0010] Thus, a wide variety of methods have been proposed for forming diamond substrates. However, (1) in homoepitaxial growth, the original substrate size is currently small, making it difficult to increase the diameter, (2) in heteroepitaxial growth, a relatively expensive substrate such as sapphire is required, and (3) although the growth on 3C-SiC uses a silicon substrate and can increase the diameter, it is difficult to do so due to the difference in the linear expansion coefficient between silicon and diamond (Si <111> :2.6×10 -6 / ℃, Diamond: 0.8×10 -6 / °C), and there is a problem of cracking during cooling. (4) In the case of heteroepitaxial growth, there are many problems that have prevented the production of large-diameter diamonds at low cost.

[0011] The present invention has been made to solve the above problems, and has an object to provide an inexpensive diamond substrate with a large diameter. Another object of the present invention is to provide a method for producing a diamond substrate, which is capable of producing a diamond substrate having a large diameter at low cost. [Means for solving the problem]

[0012] The present invention has been made to achieve the above object, and comprises a substrate, a 3C-SiC layer grown on the substrate, and a single-crystal diamond layer grown on the 3C-SiC layer, and the substrate side of the interface between the substrate and the 3C-SiC layer has a density of more than 0.001 to 10 particles / μm 2 The present invention provides a diamond substrate having voids formed therein at a density of 1000 nm to 1000 nm.

[0013] Such a diamond substrate prevents damage to the diamond substrate due to the difference in linear expansion coefficient between the substrate and the diamond layer, due to the large number of voids formed on the substrate side at the interface between the substrate and the 3C-SiC layer. Therefore, it is possible to produce a diamond substrate with a large diameter.

[0014] In addition, by using such a diamond substrate, the surface of the 3C-SiC layer can be used as a diamond seed crystal, eliminating the need for special seed formation. Furthermore, such films with multiple functions can be formed at the same time. This results in an inexpensive diamond substrate.

[0015] In this case, the substrate may be a single crystal silicon substrate having a surface orientation of (111).

[0016] This is advantageous for growing a 3C-SiC layer on the substrate.

[0017] The present invention has been made to achieve the above object, and includes a 3C-SiC growing step of growing a 3C-SiC layer on a substrate, and forming a 3C-SiC layer having a density of more than 0.001 to 10 particles / μm on the substrate side at the interface between the substrate and the 3C-SiC layer. 2 and a diamond layer growing step of growing a single crystal diamond layer on the 3C-SiC layer.

[0018] According to this method of manufacturing a diamond substrate, the large number of voids formed on the substrate side at the interface between the substrate and the 3C-SiC layer prevents damage to the diamond substrate due to the difference in linear expansion coefficient between the substrate and diamond. This allows the production of diamond substrates with large diameters.

[0019] In addition, according to this method for manufacturing a diamond substrate, the surface of the 3C-SiC layer can be used as a diamond seed crystal, eliminating the need for special seed formation. Furthermore, films with multiple functions can be formed at the same time. Therefore, the diamond substrate can be produced at low cost.

[0020] In this case, the substrate may be a single crystal silicon substrate having a surface orientation of (111).

[0021] This is advantageous for growing a 3C-SiC layer on the substrate.

[0022] In this case, in the 3C-SiC growth process, Si in the single crystal silicon substrate is diffused into the 3C-SiC layer as a raw material for SiC, and the traces of diffused Si are turned into vacancies, thereby enabling the 3C-SiC growth process and the vacancy formation process to be carried out simultaneously.

[0023] This allows a single crystal 3C-SiC layer to be grown over the entire surface of the substrate while forming voids. Effect of the Invention

[0024] As described above, according to the diamond substrate of the present invention, it is possible to provide an inexpensive diamond substrate having a large diameter. Furthermore, according to the method for producing a diamond substrate of the present invention, a diamond substrate having a large diameter can be produced at low cost. [Brief description of the drawings]

[0025] [Figure 1] 1 shows a diamond substrate according to an embodiment of the present invention. [Diagram 2] 1 shows a flow diagram of a method for manufacturing a diamond substrate according to an embodiment of the present invention. [Diagram 3] 1 shows the results of Raman measurement of the diamond substrate of Example 1, where (a) shows the Raman spectrum and (b) shows a microscope image of the surface of the diamond layer. [Figure 4] 1 shows the results of Raman measurement of the diamond substrate of Example 2, where (a) shows the Raman spectrum and (b) shows a microscope image of the surface of the diamond layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The present invention will be described in detail below, but the present invention is not limited thereto.

[0027] As mentioned above, there is a need for inexpensive, large diameter diamond substrates.

[0028] As a result of intensive research into the above-mentioned problems, the present inventors have discovered a method for manufacturing a diamond substrate comprising: a substrate; a 3C-SiC layer grown on the substrate; and a single-crystal diamond layer grown on the 3C-SiC layer, The interface between the substrate and the 3C-SiC layer is at a substrate side with a particle size of more than 0.001 to 10 particles / μm 2 The inventors have found that a diamond substrate having holes formed therein at a density of 1000 nm can be produced at low cost and with a large diameter, thereby completing the present invention.

[0029] As described above, there has also been a demand for a method of manufacturing a diamond substrate that is capable of producing a diamond substrate having a large diameter at low cost.

[0030] As a result of intensive research into the above-mentioned problems, the present inventors have discovered a method for growing a 3C-SiC layer on a substrate, comprising the steps of: forming a 3C-SiC layer on a substrate; and forming a 3C-SiC layer on the substrate side at an interface between the substrate and the 3C-SiC layer with a density of more than 0.001 to 10 particles / μm. 2 The inventors have found that a diamond substrate having a large diameter can be manufactured at low cost by a method for manufacturing a diamond substrate, the method comprising the steps of: a void formation step of forming voids at a density of 1000 nm; and a diamond layer growth step of growing a single crystal diamond layer on the 3C-SiC layer, and have completed the present invention.

[0031] The following description will be given with reference to the drawings. First, a diamond substrate according to an embodiment of the present invention will be described with reference to FIG.

[0032] As shown in FIG. 1, the diamond substrate 100 comprises a substrate 1, a 3C—SiC layer 3, and a single crystal diamond layer 4.

[0033] The substrate 1 supports the 3C-SiC layer 3 and the single crystal diamond layer 4, and serves as a base for the growth of the 3C-SiC layer 3. The substrate 1 is preferably a silicon single crystal substrate. In particular, a single crystal silicon substrate having a surface orientation of (111) is advantageous for growing the 3C-SiC layer 3 on the substrate.

[0034] The thickness of the substrate 1 is not particularly limited, but it is preferable that the thickness be such that the warping of the diamond substrate 100 is small when the 3C-SiC layer 3 and the single crystal diamond layer 4 are grown, and that the diamond substrate 100 can be loaded into a device formation apparatus when a device is formed on the diamond substrate 100. Furthermore, a larger diameter of the substrate 1 is preferable because the larger diameter of the single crystal diamond layer 4 can be obtained.

[0035] The 3C-SiC layer 3 is an intermediate layer that serves as a base when the single crystal diamond layer 4 grows, and is a single crystal layer of 3C-SiC grown on a substrate.

[0036] When the substrate 1 is a silicon single crystal substrate, the thinner the 3C-SiC layer 3, the more it can suppress warping of the diamond substrate 100 due to lattice mismatch with silicon. On the other hand, the thicker the 3C-SiC layer 3, the more it functions as an intermediate layer between the single crystal diamond layer 4 and the substrate 1, making the diamond substrate 100 less likely to crack when the single crystal diamond layer 4 is grown.

[0037] Therefore, the thickness of the 3C-SiC layer 3 may be appropriately selected within a range that allows both suppression of warping and the function as an intermediate layer, and is, for example, less than 100 nm, preferably less than 70 nm. The diameter of the 3C—SiC layer 3 is, for example, approximately the same as that of the substrate 1, but may be smaller than that of the substrate 1.

[0038] The single crystal diamond layer 4 is a layer of single crystal diamond and is grown on the 3C—SiC layer 3 . The thicker the single-crystal diamond layer 4, the higher the height of the device that can be formed. On the other hand, the thinner the layer, the less likely the diamond substrate 100 will warp or crack. Therefore, the thickness can be appropriately selected taking into consideration the height of the device to be formed and the suppression of warping or cracking of the diamond substrate 100.

[0039] Furthermore, the diameter of the single crystal diamond layer 4 is, for example, approximately the same as that of the 3C—SiC layer 3, but may be smaller than that of the 3C—SiC layer 3.

[0040] Here, the diamond substrate 100 has a density of more than 0.001 to 10 particles / μm on the substrate 1 side at the interface between the substrate 1 and the 3C-SiC layer 3. 2 The porous layer 2 has pores (microbubbles, microneedles) formed at a density of 100 nm to 150 nm.

[0041] In this way, by providing a vacancy layer 2 on the substrate 1 side at the interface between the substrate 1 and the 3C-SiC layer 3, it is possible to alleviate the lattice mismatch between the substrate 1 (e.g., silicon) and the single-crystal diamond layer 4, and to prevent damage to the diamond substrate 100 due to the difference in linear expansion coefficient between the substrate 1 and the single-crystal diamond layer 4. Therefore, the diamond substrate 100 can be made larger in diameter.

[0042] Moreover, with such a diamond substrate 100, the surface of the 3C-SiC layer 3 can be used as a seed crystal for growing the single crystal diamond layer 4, eliminating the need for special seed formation. Furthermore, such films having multiple functions can be formed at the same time. Therefore, the diamond substrate 100 is inexpensive.

[0043] However, the density of the pores in the pore layer 2 is 0.001 pores / μm 2If the density is less than 10 / μm, the density is too low and the stress caused by the difference in the linear expansion coefficient is not sufficiently relaxed. 2 If it is greater than this, the density of vacancies may be too high to support the 3C-SiC layer 3 and the single-crystal diamond layer 4.

[0044] Therefore, the density of the pores in the pore layer 2 is more than 0.001 to 10 pores / μm 2 The more preferable density is 0.002 to 1 particle / μm 2 It is. The depth (thickness) of the void layer 2 is not particularly limited, but is, for example, about 1 μm from the interface between the substrate 1 and the 3C—SiC layer 3. The size of the voids is also not particularly limited, but is, for example, about 10 nm to 5000 nm in the maximum width. The above is a description of the diamond substrate 100 according to the embodiment of the present invention.

[0045] Next, a method for manufacturing the diamond substrate 100 according to the embodiment of the present invention will be described with reference to FIG.

[0046] First, a substrate 1 is prepared (S1 in FIG. 2). As shown in FIG. 2, a silicon substrate can be used as the substrate 1, but since a single crystal silicon substrate with a (111) surface orientation is particularly advantageous for growing a 3C-SiC layer 3 on the substrate, the following description will be given taking as an example a case where a single crystal silicon substrate with a (111) surface orientation is used as the substrate 1.

[0047] Next, in a 3C-SiC growth step, a 3C-SiC layer 3 is grown on the substrate 1, and in a pore formation step, pores are formed on the substrate 1 side at the interface between the substrate 1 and the 3C-SiC layer 3 at a density of more than 0.001 to 10 pores / μm. 2 Vacancies are formed at a density of 100 nm (S2 in Fig. 2).

[0048] In the 3C-SiC growing step, it is essential to grow a single crystal of the 3C-SiC layer 3, and in the void forming step, it is necessary to provide a large number of voids in the substrate 1 directly below the 3C-SiC layer 3.

[0049] The first method for forming voids while growing the 3C-SiC layer 3 is to form a large number of projections and recesses in the projections and recesses in the projections and recesses to form voids, but it may be difficult to form a single-crystal 3C-SiC layer 3 over the entire surface of a substrate 1 having such a surface. Therefore, it is preferable to use a flat substrate 1 and adjust the growth conditions for the 3C-SiC layer 3 to perform the void formation step simultaneously with the 3C-SiC growth step.

[0050] Specifically, in the 3C-SiC growth process, it is preferable to diffuse Si in the single crystal silicon substrate 1 into the 3C-SiC layer 3 as a raw material for SiC, and leave vacancies where the Si has diffused, thereby performing the 3C-SiC growth process and the vacancy formation process simultaneously.

[0051] More specifically, the surface of the substrate 1 is carbonized, and then a raw material gas such as trimethylsilane is supplied as a Si source while adjusting the film formation conditions, thereby forming a 3C-SiC layer 3, and at the same time, Si in the single crystal silicon substrate is diffused into the 3C-SiC layer 3 as a SiC raw material, thereby forming vacancies.

[0052] In this way, when vacancies are formed by diffusing Si in a single crystal silicon substrate with a (111) surface orientation into the 3C-SiC layer 3, the shape of the vacancies reflects the surface orientation and is triangular (triangular pit) when viewed from above the substrate 1.

[0053] The density of the pores in the pore layer 2 is more than 0.001 to 10 pores / μm 2 If the density is lower than this, stress relaxation due to differences in linear expansion coefficients may be insufficient, and if the density is higher than this, the 3C—SiC layer 3 and the single crystal diamond layer 4 may not be supported.

[0054] Furthermore, these triangular voids are formed because Si from substrate 1 is used as the Si raw material when growing 3C-SiC layer 3, and as 3C-SiC layer 3 grows and becomes thicker, Si cannot diffuse from the underlying silicon single crystal substrate 1 to the surface of 3C-SiC layer 3.

[0055] Therefore, when the Si in the substrate 1 is diffused into the 3C-SiC layer 3 as a raw material for SiC and the vacancies are left as holes, the upper limit of the density is set to 10 holes / μm 2 It is practically difficult to make it larger.

[0056] Specifically, the film formation conditions for adjusting the density of voids include the flow rate of a gas (carrier gas) such as H. For example, when other film formation conditions are the same, the higher the flow rate of the carrier gas, the higher the void density.

[0057] Next, as required, as shown in FIG. 2, seed crystal growth (seeding treatment) is performed prior to the growth of the single crystal diamond layer 4 (S3 in FIG. 2).

[0058] Finally, a single crystal diamond layer 4 is grown on the 3C-SiC layer 3 (S4 in FIG. 2, diamond layer growth step). Specifically, a hot filament CVD apparatus using methane (CH4) or the like as a raw material can be applied to the growth of a large diameter single crystal diamond as in the present invention, but even a microwave plasma CVD apparatus can be used to grow a large diameter diamond substrate 100.

[0059] The diamond substrate 100 can be manufactured by the above process, but it is also possible to separate the manufactured diamond substrate 100 into the substrate 1, the 3C-SiC layer 3, and the single-crystal diamond layer 4 at the void layer 2 by, for example, applying an external force to the void layer 2.

[0060] Thus, according to the manufacturing method of the diamond substrate 100 of the present invention, when artificially growing diamond on the substrate 1, in particular when growing a single crystal diamond layer 4 on a silicon single crystal substrate 1 by CVD (chemical vapor deposition), a 3C-SiC layer 3 is used as an intermediate layer, and a vacancy layer 2 is provided on the substrate 1 side at the interface between the substrate 1 and the 3C-SiC layer 3, thereby making it possible to manufacture a large diameter diamond substrate 100 at low cost. EXAMPLES

[0061] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0062] Example 1 A boron-doped high-resistance single crystal silicon substrate having a diameter of 150 mm and a surface orientation of (111) was prepared as substrate 1, and a 3C-SiC layer 3 was grown to a thickness of 70 nm using a low-pressure CVD apparatus. The specific growth conditions for 3C-SiC layer 3 at this time were as follows:

[0063] First, the native oxide film was removed by H2 baking at 1080°C for 60 seconds, then the silicon surface was carbonized with propane while increasing the temperature from 700°C to 1100°C at 1°C / second, and then trimethylsilane (carrier gas H2 flow rate of 10 slm) was flowed at 1080°C for 10 minutes to grow the 3C-SiC layer 3 to a thickness of 70 nm, and at the same time a void layer 2 was formed. The density of voids (triangular pits) at this time was 0.002 pieces / μm 2 It was.

[0064] This substrate was introduced into a microwave plasma growth apparatus, and a single crystal diamond layer 4 was grown under the conditions of 2.45 GHz microwave at 1500 W, H2 flow rate: 10 SLM, CH4 concentration: 3%, substrate temperature: 850°C, and pressure: 60 Torr. (7999.34 Pa). The temperature of the substrate stage was adjusted so that the substrate temperature was within the range of 850°C±5°C within the plane.

[0065] After that, the substrate surface was measured by Raman scattering spectroscopy, and a peak corresponding to diamond was obtained in the Raman spectrum shown in Figure 3(a). Furthermore, when the surface was observed with a Raman microscope, grown crystals were observed as shown in Figure 3(b). Thus, the growth of a single crystal diamond layer 4 was confirmed.

[0066] Example 2 A boron-doped high-resistance single crystal silicon substrate having a diameter of 150 mm and a surface orientation of (111) was prepared, and a 3C-SiC layer 3 was grown to a thickness of 70 nm using a low-pressure CVD apparatus. The specific growth conditions for the 3C-SiC layer 3 at this time were as follows:

[0067] First, the native oxide film was removed by H2 baking at 1080°C for 60 seconds, and then the silicon surface was carbonized with propane while increasing the temperature from 700°C to 1100°C at 1°C / second. Then, trimethylsilane (carrier gas H2 at 100 slm) was flowed at 1080°C for 10 minutes to grow the 3C-SiC layer 3 to 70 nm and simultaneously form a void layer 2.

[0068] In this way, the flow rate of the carrier gas in Example 2 was made larger than that in Example 1. The density of the voids (triangular pits) at this time was 1 / μm 2 This was a higher density than Example 1.

[0069] This substrate was introduced into a microwave plasma growth apparatus, and a single crystal diamond layer 4 was grown under the conditions of 2.45 GHz microwave at 1500 W, H2 flow rate: 10 SLM, CH4 concentration: 3%, substrate temperature: 850°C, and pressure: 60 Torr. The temperature of the substrate stage was adjusted so that the substrate temperature was within the range of 850°C±5°C within the plane.

[0070] After that, the substrate surface was measured by Raman scattering spectroscopy, and a peak corresponding to diamond was obtained in the Raman spectrum shown in Figure 4(a). Furthermore, when the surface was observed with a Raman microscope, grown crystals were observed as shown in Figure 4(b). Thus, the growth of a single crystal diamond layer 4 was confirmed.

[0071] (Comparative Example) A boron-doped high-resistance single crystal silicon substrate having a diameter of 150 mm and a surface orientation of (111) was prepared, and a 3C-SiC layer 3 was grown to a thickness of 70 nm using a low-pressure CVD apparatus. The specific growth conditions for the 3C-SiC layer 3 at this time were as follows:

[0072] First, the native oxide film was removed by H2 baking at 1080°C / 60 seconds, and then the silicon surface was carbonized with propane while increasing the temperature from 700°C to 1100°C at 1°C / second, and then trimethylsilane was flowed at 900°C for 10 minutes to grow a 3C-SiC layer 3 to 70 nm.

[0073] In this way, in the comparative example, no carrier gas was flowed. The density of the voids (triangular pits) was 0.001 pieces / μm 2 , which was lower than the densities of Examples 1 and 2.

[0074] This substrate was introduced into a microwave plasma growth apparatus, and a single crystal diamond layer 4 was grown under the following conditions: 1500 W of 2.45 GHz microwave, H2 flow rate: 10 SLM, CH4 concentration: 3%, substrate temperature: 850°C, and pressure: 60 Torr. The temperature of the substrate stage was adjusted so that the substrate temperature was within the range of 850°C ± 5°C within the surface. As a result, the single crystal diamond layer 4 was formed, but cracks occurred during cooling after the film formation.

[0075] As described above, according to an embodiment of the present invention, when growing a single crystal diamond layer 4 on a silicon single crystal substrate 1 by CVD, a 3C-SiC layer 3 is used as an intermediate layer, and a void layer 2 is provided on the substrate 1 side at the interface between the substrate 1 and the 3C-SiC layer 3, thereby making it possible to manufacture a large diameter diamond substrate 100 at low cost.

[0076] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in the technical scope of the present invention. [Explanation of symbols]

[0077] 1...substrate, 2...vacancy layer, 3...3C-SiC layer, 4...single crystal diamond layer, 100...single crystal diamond substrate.

Claims

1. a substrate, a 3C-SiC layer grown on the substrate, and a single crystal diamond layer grown on the 3C-SiC layer; 0.001 to 10 particles / μm on the substrate side at the interface between the substrate and the 3C-SiC layer ２ 1. A diamond substrate having voids formed therein at a density of 1000 nm to 1000 nm.

2. 2. The diamond substrate according to claim 1, wherein the substrate is a single crystal silicon substrate having a surface orientation of (111).

3. A 3C-SiC growth step of growing a 3C-SiC layer on a substrate, and a method of forming a 3C-SiC layer on a substrate side at an interface between the substrate and the 3C-SiC layer, the method comprising: ２ a void forming step of forming voids at a density of a diamond layer growing step of growing a single crystal diamond layer on the 3C-SiC layer; A method for manufacturing a diamond substrate, comprising:

4. 4. The method for producing a diamond substrate according to claim 3, wherein a single crystal silicon substrate having a surface orientation of (111) is used as the substrate.

5. 5. The method for manufacturing a diamond substrate as described in claim 4, characterized in that in the 3C-SiC growth process, Si in the single crystal silicon substrate is diffused into the 3C-SiC layer as a raw material for SiC, and the traces of diffused Si are turned into vacancies, thereby performing the 3C-SiC growth process and the vacancy formation process simultaneously.

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