Method for manufacturing heteroepitaxial substrate

Abstract

The present invention is a method for manufacturing a heteroepitaxial substrate, which is characterized by comprising: a substrate manufacturing step for manufacturing a single-crystal silicon substrate under a thickness condition that exceeds the upper limit of a thickness specification determined according to the diameter of the single-crystal silicon substrate and is not more than 2 mm; an epitaxial step for obtaining an epitaxial substrate by growing a heteroepitaxial layer on the single crystal silicon substrate obtained in the substrate manufacturing step; and a thinning step for grinding the surface of the single crystal silicon substrate after the epitaxy step, said surface being on the opposite side from the surface on which the heteroepitaxial layer is formed, and thinning the single crystal silicon substrate to a thickness specification range. As a result, provided is a method for manufacturing a heteroepitaxial substrate, which can be used in conventional apparatus processes even when a heteroepitaxial layer is formed by making the thickness of a single crystal silicon substrate thicker than a standard thickness.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a heteroepitaxial substrate. Background Art

[0002] The technology of forming various heteroepitaxial layers, including diamond, on a single crystal silicon substrate is a very effective method because it grows expensive materials on cheap silicon materials, so it can be made large-diameter at a low cost. However, since a material different from silicon is grown, the lattice constant and linear expansion coefficient are different from silicon, so stress is generated in the substrate after epitaxial growth, and there is a problem that the stress causes the substrate to warp or, in the worst case, cracks in the substrate and damage.

[0003] Therefore, a method of adjusting the light element content in the substrate to ensure the strength of silicon has been proposed (Patent Documents 1 to 3), and in addition to the method of adjusting the content, a method of controlling the thickness of the single crystal silicon substrate itself (basically increasing the thickness) has also been proposed. For example, in Patent Document 4, when a diamond layer is formed on a single crystal silicon substrate to make a composite substrate, the lower limit of the thickness of the silicon support substrate is preferably 0.05 mm or more, more preferably 0.2 mm or more, and the upper limit of the thickness is 5 mm or less.

[0004] Furthermore, in Patent Document 5, it is proposed that the thickness of the single crystal silicon substrate is 0.3~2mm, in Patent Document 6, a substrate for growing single crystal diamond is proposed, wherein at least the thickness of the single crystal silicon substrate is 0.03mm~20.00mm, in Patent Document 7, a base substrate composed of single crystal silicon (Si) is proposed, and its thickness is greater than 0.03mm and less than 20.00mm, in Patent Document 8, a diamond-forming structure for forming single crystal diamond and a method for manufacturing the structure are proposed, wherein the thickness of the base substrate is about 0.01~15mm, and in Patent Document 9, it is proposed that the thickness of the silicon substrate for growing a self-supporting diamond film be made greater than 4mm or greater than 2mm.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2020-102598

[0008] Patent Document 2: Japanese Patent Application Publication No. 2022-124012

[0009] Patent Document 3: Japanese Patent Application Publication No. 2002-261011

[0010] Patent Document 4: International Publication No. 2019 / 039533

[0011] Patent Document 5: Japanese Patent Application Publication No. 2009-238971

[0012] Patent Document 6: Japanese Patent Application Publication No. 2011-079683

[0013] Patent Document 7: Japanese Patent Application Publication No. 2012-001394

[0014] Patent Document 8: Japanese Patent Application Publication No. 2022-068862

[0015] Patent Document 9: International Publication No. 2016 / 168796 Summary of the invention

[0016] 1. Technical issues to be resolved

[0017] Thus, focusing on the thickness of the single crystal silicon substrate when heteroepitaxial growth is performed on the single crystal silicon substrate, it is proposed to suppress warping or cracking by increasing the thickness. However, when the thickness of the single crystal silicon substrate is made thicker than before, the thickness will be different from the thickness of each caliber standardized by the SEMI (International Semiconductor Industry Association) standard for silicon devices. Such a substrate with a thickness different from the standardized thickness cannot be put into the existing device process. Even if a heteroepitaxial layer can be formed, in the subsequent process, that is, various materials headed by diamond are used in the device or in the process of bonding treatment, there will be a problem that it cannot be put into the subsequent process due to the different thickness, which has a great problem in using it as a semiconductor device. This is because when the epitaxial substrate is put into the manufacturing device of the semiconductor device used in the subsequent process after the heteroepitaxial growth, the manufacturing device is also a structure that can only put in the epitaxial substrate of the size specified by the SEMI standard. In addition, although it is theoretically possible to make a dedicated process for thick film substrates of diamond or various materials, it is not feasible to prepare various processes for processing thick film substrates. The cost will increase significantly.

[0018] The present invention is made to solve the above-mentioned problems, and its object is to provide a method for manufacturing a heteroepitaxial substrate which can be put into existing equipment processes even when the thickness of a single crystal silicon substrate is made thicker than the specification to form a heteroepitaxial layer.

[0019] (II) Technical solution

[0020] The present invention is a technology related to a single crystal silicon substrate used for heteroepitaxial growth, including diamond growth on a single crystal silicon substrate. More specifically, it is a technology that optimizes the thickness of the single crystal silicon substrate to suppress wafer breakage during heteroepitaxial growth, while allowing the epitaxial substrate after the growth of the heteroepitaxial layer to be put into existing device processes.

[0021] Specifically, the present invention is completed to achieve the above-mentioned purpose and provides a method for manufacturing a heteroepitaxial substrate, characterized in that it includes: a substrate manufacturing process, manufacturing the single crystal silicon substrate with a thickness condition exceeding the upper limit of the thickness specification determined by the diameter of the single crystal silicon substrate and being below 2 mm; an epitaxial process, growing a heteroepitaxial layer on the single crystal silicon substrate obtained in the substrate manufacturing process to obtain an epitaxial substrate; and a thinning process, grinding the surface of the single crystal silicon substrate after the epitaxial process which is opposite to the surface on which the heteroepitaxial layer is formed, to thin the single crystal silicon substrate to within the range of the thickness specification.

[0022] In this method, as a single crystal silicon substrate for heteroepitaxial growth including diamond on a single crystal silicon substrate, a thick substrate exceeding the upper limit of the thickness specification, that is, a single crystal silicon substrate having higher rigidity than a substrate within the thickness specification is prepared, and the substrate is used to grow a heteroepitaxial layer using heteroepitaxial materials including diamond, thereby suppressing warping or cracking. In addition, after the growth of the heteroepitaxial layer, the surface of the single crystal silicon substrate opposite to the surface on which the heteroepitaxial layer is formed is processed by grinding, polishing, etc., and the single crystal silicon substrate is thinned to a thickness specification determined according to each caliber, thereby enabling the use of existing device processes.

[0023] This makes it possible to manufacture heteroepitaxial substrates such as diamond that are suitable for existing silicon processes while suppressing warping or cracking, and even when the thickness of a single crystal silicon substrate is made thicker than the standard to form a heteroepitaxial layer, existing device processes can still be used.

[0024] The epitaxial growth step may be a step of growing a heteroepitaxial layer of any one of GaN, AlN, and diamond.

[0025] By using GaN as the material constituting the heteroepitaxial layer, when forming a semiconductor device, the device becomes a device with a higher dielectric breakdown voltage and a faster electron saturation velocity than a silicon semiconductor device. By using AlN and diamond as the material constituting the heteroepitaxial layer, when forming a semiconductor device, the device becomes a device with a much higher dielectric breakdown voltage than a silicon semiconductor device.

[0026] Before performing the substrate manufacturing process, a thickness determination process can be performed. This thickness determination process pre-calculates the relationship between the thickness of the single crystal silicon substrate and the thickness of the heteroepitaxial layer in which the epitaxial substrate will not break after the epitaxial process, and determines the thickness of the single crystal silicon substrate manufactured in the substrate manufacturing process and the thickness of the heteroepitaxial layer grown in the epitaxial process based on the calculated relationship.

[0027] In this configuration, since the thickness of the single crystal silicon substrate and the thickness of the heteroepitaxial layer are determined in advance based on the relationship between the thickness of the single crystal silicon substrate and the thickness of the heteroepitaxial layer that can be grown without breaking the epitaxial substrate, the thickness of the single crystal silicon substrate and the heteroepitaxial layer can be set to the necessary and sufficient thickness to prevent the epitaxial substrate from breaking.

[0028] (III) Beneficial effects

[0029] According to the configuration of the present invention, a substrate is provided which can perform heteroepitaxial growth without breaking the epitaxial substrate even when a heteroepitaxial layer is grown on a large-diameter single-crystal silicon substrate, and can be applied to a manufacturing process of a semiconductor device of existing specifications.

[0030] More specifically, even when the thickness of the single crystal silicon substrate is made thicker than the specification to form a heteroepitaxial layer, the existing device process can still be used later. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram showing an epitaxial substrate manufactured by the method for manufacturing a heteroepitaxial substrate of the present invention.

[0032] Figure 2 The following is an overview of the flow of a method for manufacturing a heteroepitaxial substrate according to the present invention. DETAILED DESCRIPTION

[0033] As described above, there is a demand for a method for manufacturing a heteroepitaxial substrate that can be applied to existing equipment processes even when a heteroepitaxial layer is formed by making the thickness of a single crystal silicon substrate thicker than the specification.

[0034] The inventors of the present application have repeatedly conducted in-depth studies on the above-mentioned problems, and as a result, have found that a method for manufacturing a heteroepitaxial substrate can be used in existing equipment processes even when the thickness of a single crystal silicon substrate is made thicker than the specification to form a heteroepitaxial layer, thereby completing the present invention. The method for manufacturing the heteroepitaxial substrate is characterized in that it includes: a substrate manufacturing process, manufacturing the single crystal silicon substrate with a thickness condition that exceeds the upper limit of the thickness specification determined by the diameter of the single crystal silicon substrate and is below 2 mm; an epitaxial process, growing a heteroepitaxial layer on the single crystal silicon substrate obtained in the substrate manufacturing process to obtain an epitaxial substrate; and a thinning process, grinding the surface of the single crystal silicon substrate after the epitaxial process that is opposite to the surface on which the heteroepitaxial layer is formed, to thin the single crystal silicon substrate to within the range of the thickness specification.

[0035] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

[0036] First, refer to Figure 1 , the structure of the epitaxial substrate 5 manufactured by the method for manufacturing a heteroepitaxial substrate according to an embodiment of the present invention will be briefly described.

[0037] like Figure 1 As shown, an epitaxial substrate 5 as a heteroepitaxial substrate includes a single crystal silicon substrate 1 and a heteroepitaxial layer 3 formed on one surface of the single crystal silicon substrate 1 .

[0038] The single crystal silicon substrate 1 is a single crystal silicon substrate that serves as a support substrate when the heteroepitaxial layer 3 is grown. Its size and shape can be appropriately selected according to the material, size, and shape of the heteroepitaxial layer 3 to be grown. A disk-shaped substrate called a wafer can be exemplified.

[0039] The wafer corresponds to Figure 1 The diameter D1 (also called the aperture) and the thickness t1 are determined by the SEMI standard M1 and other specifications. Therefore, the semiconductor device manufacturing apparatus used in the subsequent process after forming the heteroepitaxial layer 3 also becomes a structure that can only input the epitaxial substrate 5 of the size determined by the SEMI standard.

[0040] The diameter determined by the SEMI standard and the thickness specification determined corresponding to the diameter are shown in the following Table 1, for example.

[0041] [Table 1]

[0042]

[0043] The heteroepitaxial layer 3 is a layer in which a semiconductor device is formed, and is composed of a heteroepitaxial material, that is, a material different from silicon.

[0044] The above is a brief description of the structure of the epitaxial substrate 5 .

[0045] Next, refer to Figure 1 and Figure 2 A method for manufacturing a heteroepitaxial substrate according to an embodiment of the present invention will be described.

[0046] First, a single crystal silicon substrate 1′ ( Figure 2 In order to manufacture a single crystal silicon substrate 1' satisfying such a thickness condition, the single crystal silicon substrate 1' may be sliced ​​thicker when the single crystal silicon ingot is sliced ​​to obtain the single crystal silicon substrate 1'.

[0047] The thickness condition is Figure 1 It is recorded as thickness t2.

[0048] By setting the thickness condition to a thickness exceeding the upper limit of the thickness specification, the rigidity of the single crystal silicon substrate 1' becomes higher than when the thickness t2 of the single crystal silicon substrate 1' is the thickness t1 within the range of the thickness specification, so that warping or cracking during the growth of the heteroepitaxial layer 3 can be suppressed. This point will be described in detail.

[0049] For example, when the material of the heteroepitaxial layer 3 is diamond, as shown in Table 2, the lattice constant and linear expansion coefficient of diamond are different from those of single crystal silicon, so stress will be generated in the epitaxial substrate 5 after epitaxial growth, and there is a concern that warping or, in the worst case, cracking will occur.

[0050] [Table 2]

[0051]

[0052] Furthermore, warping and cracking can also cause adverse effects during the epitaxial growth of diamond by CVD (chemical vapor deposition) or the like. For example, the epitaxial substrate 5 warps during epitaxial growth, thereby changing the temperature distribution of the growing epitaxial substrate 5, which can easily lead to a situation where the uniformity of the film thickness or the like deteriorates. Furthermore, from the perspective of reactor management, it is not preferred to place a substrate with a high possibility of cracking in a reactor for epitaxial growth.

[0053] Therefore, by setting the thickness condition to a thickness t2 exceeding the upper limit of the thickness specification, the rigidity of the single crystal silicon substrate 1' becomes higher than that of the single crystal silicon substrate 1' when the thickness is a thickness t1 within the range of the thickness specification, and it is possible to suppress the warping and cracking of the epitaxial substrate 5 after growth, or suppress the film thickness from becoming uneven during epitaxial growth. In addition, by suppressing the warping and cracking of the epitaxial substrate 5, the management of the reactor becomes easier.

[0054] In addition, as long as the epitaxial substrate 5 after the epitaxial process is not broken, the thickness t2 of the single crystal silicon substrate 1' can also be set to be thinner than the thickness exceeding the upper limit of the thickness specification. However, if the flatness or rigidity of the single crystal silicon substrate 1' is considered, it is preferred to make the thickness t2 exceed the upper limit of the thickness specification.

[0055] The reason for setting the thickness condition to less than 2 mm is as follows. The present invention improves rigidity by setting the thickness of the single crystal silicon substrate 1' to be thicker than the upper limit of the thickness specification, thereby suppressing warping or cracking when the heteroepitaxial layer 3 grows. Therefore, if the growth is performed simply considering suppressing warping or cracking, the thicker the thickness t2 of the single crystal silicon substrate 1', the better. However, if it is considered that the thicker the thickness t2, the more labor or cost is consumed for processing to set the flatness of the single crystal silicon substrate 1' to the desired range, processing of the end portions, and subsequent thinning, it can be easily imagined that the upper limit of the thickness t2 is limited.

[0056] Specifically, taking a single crystal silicon substrate 1′ with a diameter of 300 mm as an example, if the groove width of the storage box or the gap of the device is taken into consideration, the upper limit of the thickness t2 is 2 mm. This upper limit of 2 mm is also the same for substrates with diameters other than 300 mm. In the era of small-diameter single crystal silicon substrates 1′ that can be manufactured with a smaller diameter than today, there is also a problem of device accuracy. The thickness of the wafer is indeed thinner than the case of a diameter of 300 mm, but a gap of 2 mm is ensured in the storage box device.

[0057] Therefore, it is preferable that the thickness t2 be set to a thickness condition of 2 mm or less.

[0058] Next, a heteroepitaxial layer 3 is grown on the single crystal silicon substrate 1' obtained in the substrate manufacturing step to obtain an epitaxial substrate 5 ( Figure 2 S2, epitaxial process).

[0059] In the epitaxial growth step, the heteroepitaxial layer 3 is formed of a material different from silicon and capable of forming a desired device.

[0060] For example, the epitaxial step is a step of growing the heteroepitaxial layer 3 of any one of GaN, AlN, and diamond.

[0061] By growing GaN as the heteroepitaxial layer 3, when a semiconductor device is formed in the heteroepitaxial layer 3, the device becomes a device with a higher dielectric breakdown voltage and a faster electron saturation velocity than a silicon semiconductor device. By growing AlN or diamond as the heteroepitaxial layer 3, when a semiconductor device is formed in the heteroepitaxial layer 3, the device becomes a device with a much higher dielectric breakdown voltage than a silicon semiconductor device.

[0062] The method for growing the heteroepitaxial layer 3 is not particularly limited, and any method may be used as long as the desired heteroepitaxial layer 3 can be formed. For example, a known growth method such as CVD may be used. Figure 2 The example described in the embodiment is a case where seed particles such as diamond are implanted into a substrate, a process called seeding, and then a diamond heteroepitaxial layer 3 is grown by CVD. However, a process called scratching can also be performed to roughen the substrate surface and introduce scratches to serve as growth cores, and then a heteroepitaxial layer 3 is grown by CVD.

[0063] The thickness of the heteroepitaxial layer 3 increases as the growth temperature increases or the growth time increases, and can therefore be adjusted by the growth temperature and the growth time. The upper limit of the thickness is a thickness that does not cause the epitaxial substrate 5 to warp or crack due to stress caused by the difference in lattice constant or linear expansion coefficient between the single crystal silicon substrate 1' and the heteroepitaxial layer 3. The lower limit of the thickness is a thickness that allows the heteroepitaxial layer 3 to maintain its shape as a layer and form a device without disappearing due to etching or grinding during formation.

[0064] Once the epitaxial process is completed, the surface (back side) of the single crystal silicon substrate 1′ after the epitaxial process, which is opposite to the surface on which the heteroepitaxial layer 3 is formed, is then ground to thin the single crystal silicon substrate 1′ to within the thickness specification range, thereby manufacturing the single crystal silicon substrate 1( Figure 2 S3, thinning process).

[0065] Since the thickness t2 of the single crystal silicon substrate 1' of the epitaxial substrate 5 after the epitaxial process exceeds the upper limit of the thickness specification, it cannot be directly put into the semiconductor process. Therefore, by thinning the single crystal silicon substrate 1' to within the range of the thickness specification determined according to each caliber in the thinning process, even if the heteroepitaxial layer 3 is formed in a manner that the thickness of the single crystal silicon substrate 1' is thicker than the specification, the thickness of the epitaxial substrate 5 after the thinning process can be made within the range of the thickness specification. Therefore, the epitaxial substrate 5 can be put into the existing device process such as the semiconductor process.

[0066] Figure 1 The thickness t1 of the single crystal silicon substrate 1 after the thinning step is within the range of thickness standards of SEMI standards, etc. Considering the flatness of the single crystal silicon substrate 1, it is advantageous to set the lower limit of the thickness to the lower limit of the thickness standards corresponding to the current diameters.

[0067] Furthermore, since the existing device process can be incorporated, the upper limit of the thickness t1 of the single crystal silicon substrate 1 after the thinning step is equal to or less than the upper limit of the thickness specification of the SEMI standard.

[0068] Thinning methods include grinding, polishing, H-based + Various techniques such as ion implantation and stripping are not particularly limited. In the single crystal silicon substrate 1, the quality of the surface opposite to the surface on which the heteroepitaxial layer 3 is formed, such as the glossiness, can be optimized according to each process. In addition, the thickness of the thinned epitaxial substrate 5 can be specified according to the thickness t3 of the heteroepitaxial layer 3 grown on the surface, or according to the thickness t1 of the single crystal silicon substrate 1. These regulations can be optimized according to each process. In the following description, unless otherwise specified, the case where the thickness of the single crystal silicon substrate 1 in the thinned epitaxial substrate 5 is specified according to t1 is used as an example for explanation.

[0069] In addition, there is a relationship between the thickness of the single crystal silicon substrate 1' manufactured in the substrate manufacturing process and the thickness of the heteroepitaxial layer 3 without cracking the epitaxial substrate 5 after the epitaxial process. Specifically, the thicker the single crystal silicon substrate 1', the thicker the heteroepitaxial layer 3 without cracking the epitaxial substrate 5 after the epitaxial process.

[0070] Therefore, it is preferred that the relationship between the thickness of the single crystal silicon substrate 1′ and the thickness of the heteroepitaxial layer 3 at which the epitaxial substrate 5 after the epitaxial process will not be cracked is determined in advance before the substrate manufacturing process is performed, and the thickness of the single crystal silicon substrate 1′ manufactured in the substrate manufacturing process and the thickness of the heteroepitaxial layer 3 grown in the epitaxial process are determined based on the determined relationship ( Figure 2 S0, thickness determines the process).

[0071] In this configuration, the thickness of the single crystal silicon substrate 1' and the thickness of the heteroepitaxial layer 3 are determined in advance based on the relationship between the thickness of the single crystal silicon substrate 1' and the thickness of the heteroepitaxial layer 3 so that the epitaxial substrate 5 after the epitaxial process will not be broken. Therefore, the thickness of the single crystal silicon substrate 1' and the heteroepitaxial layer 3 can be set to an appropriate thickness that is necessary and sufficient so that the epitaxial substrate 5 will not be broken.

[0072] The above is the description of the method for manufacturing the heteroepitaxial substrate of the present invention.

[0073] Thus, according to the present invention, a thick substrate exceeding the upper limit of the thickness specification is prepared as a single crystal silicon substrate 1' for heteroepitaxial growth, including diamond, and a heteroepitaxial layer 3 is grown, thereby suppressing warping or cracking. In addition, after the growth of the heteroepitaxial layer 3, the single crystal silicon substrate 1' is thinned to a thickness specification determined according to each caliber, thereby being able to be put into the existing device process.

[0074] Thus, heteroepitaxial growth such as diamond applicable to existing silicon processes can be performed while suppressing warping or cracking, and existing equipment processes can be used even when the heteroepitaxial layer 3 is formed in a manner that the thickness of the single crystal silicon substrate 1' is thicker than the standard.

[0075] Example

[0076] Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

[0077] The thickness of the single crystal silicon substrate 1' is made thicker than the thickness specification, and the thickness is reduced after the heteroepitaxial layer 3 is formed, thereby manufacturing the epitaxial substrate 5, and the presence or absence of cracks is compared with the case where the heteroepitaxial layer 3 is formed on the single crystal silicon substrate 1' within the thickness specification. The specific procedure is as follows.

[0078] First, as a substrate manufacturing process, a high-resistance single-crystal silicon substrate (resistivity 100Ω·cm) doped with boron and having a diameter of 300 mm and a surface orientation of (111) was prepared as a single-crystal silicon substrate 1′, and the surface was ground with a #8000 grindstone to roughen the silicon surface and introduce scratches as the core of diamond growth. At this time, a total of four types of high-resistance single-crystal silicon substrates of different thicknesses were prepared as the single-crystal silicon substrate 1′, namely, a substrate of 0.775 mm (comparative example) corresponding to the normal thickness of the SEMI standard with a diameter of 300 mm, and substrates of 1 mm, 1.5 mm, and 2 mm thicker than the SEMI standard (exemplary embodiment).

[0079] Next, as an epitaxial process, these substrates were placed in a hot filament CVD device with a filament temperature of 2200°C and H 2 Flow rate: 10SLM, CH 4 The conditions of concentration: 3%, substrate temperature: 850°C, and pressure in the device of 5 Torr. (666.612 Pa) were used to perform epitaxial growth of diamond for three groups of film formation time of 2 hours, 4 hours, and 8 hours, and to test the manufacture of epitaxial substrate 5. As shown in Table 3, when the growth time increased and the diamond heteroepitaxial layer 3 became thicker, a substrate was produced that cracked after the epitaxial process.

[0080] [Table 3]

[0081]

[0082] Finally, as a thinning step, the single crystal silicon substrate 1' of the epitaxial substrate 5 that was not cracked in the epitaxial step was thinned by grinding to within the range of SEMI standards, that is, 0.775±20 mm (775±20 μm), and no cracks were generated in the epitaxial substrate 5 after thinning.

[0083] From the above results, it can be seen that even if a single crystal silicon substrate 1′ would crack when forming a heteroepitaxial layer 3 within the range of the thickness specification, it is possible to grow the heteroepitaxial layer 3 with a thickness set to be thicker than the thickness specification and then thin it to within the thickness specification, thereby suppressing cracking while making it a thickness that can be used in existing device processes.

[0084] The present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any technical solution having substantially the same structure and exerting the same function and effect as the technical concept described in the claims of the present invention is included in the technical scope of the present invention.

Claims

1. A method for manufacturing a heteroepitaxial substrate, It is characterized in that It includes: A substrate manufacturing step of manufacturing the silicon single crystal substrate under a thickness condition that exceeds an upper limit of a thickness specification determined according to a diameter of the silicon single crystal substrate and is less than 2 mm; An epitaxial step of growing a heteroepitaxial layer on the silicon single crystal substrate obtained in the substrate manufacturing step to obtain an epitaxial substrate; and The thinning step is to grind the surface of the silicon single crystal substrate after the epitaxial step, which is opposite to the surface on which the heteroepitaxial layer is formed, to thin the silicon single crystal substrate to within the range of the thickness specification.

2. The method for manufacturing a heteroepitaxial substrate according to claim 1, It is characterized in that The epitaxial growth step is a step of growing the heteroepitaxial layer of any one of GaN, AlN, and diamond.

3. The method for manufacturing a heteroepitaxial substrate according to claim 1 or 2, It is characterized in that A thickness determination process is performed before the substrate manufacturing process, and the thickness determination process pre-calculates the relationship between the thickness of the single crystal silicon substrate and the thickness of the heteroepitaxial layer in which the epitaxial substrate will not break after the epitaxial process, and determines the thickness of the single crystal silicon substrate manufactured in the substrate manufacturing process and the thickness of the heteroepitaxial layer grown in the epitaxial process based on the calculated relationship.

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