Method for producing 3C-SiC single crystal epitaxial substrate, method for producing 3C-SiC self-supporting substrate, and 3C-SiC single crystal epitaxial substrate

Abstract

The present invention is a method for producing a 3C-SiC single crystal epitaxial substrate, which is characterized by comprising: a hydrogen baking step in which a natural oxide film on the surface of a single crystal silicon substrate is removed by annealing the single crystal silicon substrate in a hydrogen atmosphere; an epitaxy step in which the surface of the single crystal silicon substrate after the hydrogen baking step is subjected to a carbonization treatment to generate a SiC nucleus, and a 3C-SiC single crystal film is epitaxially grown using the generated nucleus as a starting point to obtain a 3C-SiC single crystal epitaxy substrate; and a diffusion step in which the 3C-SiC single crystal epitaxial substrate is heated to a temperature lower than the melting point of Si in a gas atmosphere containing carbon, the Si in the single crystal silicon substrate is diffused in a solid state to the interface between the 3C-SiC single crystal film and the single crystal silicon substrate, and the diffused Si reacts in a solid state with C reaching the interface to further grow SiC. As a result, a hole layer having holes generated at Si diffusion traces is formed at the interface between the single crystal silicon substrate and the 3C-SiC single crystal film. As a result, it is possible to provide a method for producing a 3C-SiC single crystal epitaxial substrate by which a large-diameter 3C-SiC self-supporting substrate can be obtained by a simple production process.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a 3C-SiC single crystal epitaxial substrate, a method for manufacturing a 3C-SiC self-supporting substrate, and a 3C-SiC single crystal epitaxial substrate. Background Art

[0002] Silicon carbide (SiC) has a wide bandgap of 2.2 to 3.3 eV, thus having a high insulation breakdown strength, and is a material that can be expected to be used for various semiconductor devices such as power devices and high-frequency devices because of its large thermal conductivity. In addition, SiC is known to have 3C, 4H, 6H, etc. with different crystal structures, but 3C is known to be a cubic crystal and a promising material without orientation dependence in devices.

[0003] Under such a background, the growth of 3C-SiC has been studied for a long time, and bulk growth (non-patent documents 1 and 2) and heteroepitaxial growth (non-patent document 3: initial heteroepitaxial growth; heteroepitaxial growth on a silicon substrate in patent documents 1 to 5) are known.

[0004] Summarizing these existing studies and patents, (1) bulk growth requires a high temperature (>1500 °C) and it is very difficult to increase the diameter to be applicable to devices; (2) on the other hand, in epitaxial growth, 4H and 6H do not require a high temperature (>1500 °C) and can be grown at a temperature of about 1100 °C, so they can be grown on a silicon substrate and are advantageous in terms of increasing the diameter.

[0005] Therefore, the heteroepitaxial growth of 3C-SiC on a single-crystalline silicon substrate and only retaining the 3C-SiC epitaxial film has been studied (non-patent document 4). In this method, after growing about 100 μm of 3C-SiC on a Si(111) substrate, silicon (Si) is removed using fluonitric acid to fabricate a 2-inch 3C-SiC self-supporting substrate. This method requires an additional etching process after growth.

[0006] In addition, patent documents 6 and 7 disclose a method in which a film with a higher melting point such as SiC is grown on a substrate with a lower melting point such as Si, and then the substrate with a lower melting point is melted at a high temperature.

[0007] In addition, regarding the growth of 3C-SiC, as described in patent document 8, it discloses that growth can also be carried out at a low temperature by maintaining an excess of Si atoms relative to C atoms on the SiC crystal growth surface. At this time, the supply sources of Si and C are generally gases.

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-522412

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 2021-20819

[0012] Patent Document 3: Japanese Patent Application Laid-Open No. 2006-253617

[0013] Patent Document 4: Japanese Patent Application Laid-Open No. 2008-184361

[0014] Patent Document 5: Japanese Patent Application Laid-Open No. 2017-39622

[0015] Patent Document 6: US Patent Application Publication No. 2013 / 157448 Specification

[0016] Patent Document 7: US Patent Application Publication No. 2016 / 307800 Specification

[0017] Patent Document 8: Japanese Patent Application Laid-Open No. 11-162850

[0018] Non-Patent Literature

[0019] Non-Patent Literature 1: H. Nagasawa, K. Yagi and T. Kawahara, “3C-SiC hetero-epitaxial growth on undulant Si(001) substrate”, Journal of Crystal Growth, 239 (2002), p1244.

[0020] Non-Patent Literature 2: D. Chaussende, F. Mercier, A. Boulle, F. Conchon, M. Soueidan, G. Ferro, A. Mantzari, A. Andreadou, E. K. Polychroniadis, C. Balloud, S. Juillaguet, J. Camassel and M. Pons, “Prospects for 3C-SiC bulk crystal growth” Journal of Crystal Growth, 310(2008), p976.

[0021] Non-Patent Document 3: T. Ujihara, R. Maekawa, R. Tanaka, K. Sasaki, K. Kuroda and Y. Takeda, “Solution growth of high-quality 3C-SiC crystals”, Journal of Crystal Growth, 310 (2008) p1438.

[0022] Non-Patent Document 4: Asamura et al., “Crystallinity evaluation of 3C-SiC(111) self-supporting substrate grown at low temperature”, Proceedings of the 62nd Spring Meeting of the Japan Society of Applied Physics, Preprint Collection 13-095 (2015), The Japan Society of Applied Physics Summary of the Invention

[0023] (1) Technical Problem to be Solved

[0024] In methods such as those in Non-Patent Document 4 and Patent Documents 6 and 7, where the Si of the substrate is melted and only the SiC epitaxial layer is left, how to handle the melted Si becomes a very big problem, and there may be problems such as residues remaining inside the epitaxial growth apparatus. In addition, from the vapor pressure of Si, it is easy to imagine that a considerably high temperature and time (1908K / 1Pa) are required to vaporize all of the Si.

[0025] The present invention has been completed to solve the above problems, and its object is to provide a method for manufacturing a 3C-SiC single crystal epitaxial substrate, a method for manufacturing a 3C-SiC self-supporting substrate, and a 3C-SiC single crystal epitaxial substrate. The method for manufacturing the 3C-SiC single crystal epitaxial substrate can obtain a large-diameter 3C-SiC self-supporting substrate using a simple manufacturing process, and the 3C-SiC single crystal epitaxial substrate can obtain a large-diameter 3C-SiC self-supporting substrate through a simple manufacturing process.

[0026] (2) Technical Solution

[0027] The present invention is completed to achieve the above object, and provides a method for manufacturing a 3C-SiC single crystal epitaxial substrate, which is characterized by including the following steps: a hydrogen baking step of removing a natural oxide film on the surface of the single crystal silicon substrate by annealing the single crystal silicon substrate in a hydrogen atmosphere; an epitaxial step of performing carbonization treatment on the surface of the single crystal silicon substrate after the hydrogen baking step to generate nuclei of SiC, and further epitaxially growing a 3C-SiC single crystal film starting from the generated nuclei to obtain a 3C-SiC single crystal epitaxial substrate; and a diffusion step of heating the 3C-SiC single crystal epitaxial substrate in a gas atmosphere containing carbon to a temperature lower than the melting point of Si (1412 ± 2 °C: cited from page 919 of "Science of Silicon" published by REALIZE Corporation), so that Si in the single crystal silicon substrate solid-state diffuses to the interface between the 3C-SiC single crystal film and the single crystal silicon substrate, and the diffused Si reacts with C reaching the interface by a solid-phase reaction to further grow SiC, thereby forming a void layer at the interface between the single crystal silicon substrate and the 3C-SiC single crystal film, and the void layer has voids generated at the diffusion traces of Si.

[0028] According to this manufacturing method, after epitaxially growing a 3C-SiC single crystal film on a single crystal silicon substrate, Si in the substrate solid-state diffuses to the interface with the 3C-SiC single crystal film, reacts with C by a solid-phase reaction to grow SiC, and at the same time, a void layer having voids generated at the diffusion traces of Si is formed at the interface. Thus, peeling can be carried out starting from the void layer through subsequent cooling or the like, so as to separate the 3C-SiC single crystal film from the single crystal silicon substrate.

[0029] According to such a method, when obtaining a 3C-SiC self-supporting substrate from a 3C-SiC single crystal epitaxial substrate formed by growing a 3C-SiC single crystal on a single crystal silicon substrate, there is no need to perform a process that raises the temperature to a high temperature to melt Si, which has a great impact on the subsequent furnace maintenance due to the molten Si, and there is also no need to add an etching process for peeling subsequently.

[0030] Therefore, a large-diameter 3C-SiC self-supporting substrate can be obtained through a simple manufacturing process.

[0031] At this time, the epitaxial step and the diffusion step can be performed in a pressure range of 133.322 Pa or more and 13332.2 Pa or less.

[0032] By setting the epitaxial step and the diffusion step to 133.322 Pa or more, the epitaxial step and the diffusion step can be performed without using a special decompression device. In addition, by setting it to 13332.2 Pa or less, the epitaxial growth of 3C-SiC in the epitaxial step and the diffusion of Si in the diffusion step can be promoted.

[0033] In addition, the present invention provides a method for manufacturing a 3C-SiC self-supporting substrate, which is characterized by including the following steps: a separation step, in which the 3C-SiC single crystal epitaxial substrate manufactured by the manufacturing method described above is cooled, thereby peeling the 3C-SiC single crystal epitaxial substrate along the void layer, separating the 3C-SiC single crystal film from the single crystal silicon substrate, and thus manufacturing a 3C-SiC self-supporting substrate.

[0034] According to such a method, when obtaining a 3C-SiC self-supporting substrate from a 3C-SiC single crystal obtained by growing a 3C-SiC single crystal on a silicon substrate, only cooling is required to separate the silicon substrate from the 3C-SiC single crystal, without the need to perform a process such as raising the temperature to a high temperature to melt Si, which has a great impact on the subsequent furnace maintenance due to the molten Si, and there is also no need to additionally perform an etching process for peeling later.

[0035] Therefore, a large-diameter 3C-SiC self-supporting substrate can be obtained through a simple manufacturing process.

[0036] Furthermore, the present invention provides a 3C-SiC single crystal epitaxial substrate, which is characterized by including: a single crystal silicon substrate, and a 3C-SiC single crystal film of an epitaxial structure provided on the single crystal silicon substrate, wherein the single crystal silicon substrate has a void layer at the interface with the 3C-SiC single crystal film, and the void layer includes a collection of voids generated by the shedding of Si.

[0037] In such a 3C-SiC single crystal epitaxial substrate, since there is a void layer containing a collection of voids generated by the shedding of Si at the interface with the 3C-SiC single crystal film, even without melting Si or performing an etching for peeling, the 3C-SiC single crystal film can be separated from the single crystal silicon substrate by peeling starting from the void layer through cooling or the like.

[0038] Therefore, a large-diameter 3C-SiC self-supporting substrate can be obtained through a simple manufacturing process.

[0039] (III) Beneficial effects

[0040] As described above, according to the manufacturing method of the 3C-SiC single crystal epitaxial substrate of the present invention, a 3C-SiC single crystal epitaxial substrate can be manufactured, which can obtain a large-diameter 3C-SiC self-supporting substrate through a simple manufacturing process.

[0041] In addition, according to the manufacturing method of the 3C-SiC self-supporting substrate of the present invention, a large-diameter 3C-SiC self-supporting substrate can be obtained through a simple manufacturing process.

[0042] Furthermore, the 3C-SiC single crystal epitaxial substrate according to the present invention can obtain a large-diameter 3C-SiC self-supporting substrate through a simple manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of a 3C-SiC single crystal epitaxial substrate showing an embodiment of the present invention is shown.

[0044] Figure 2 A flowchart showing a method for manufacturing a 3C-SiC single crystal epitaxial substrate and a method for manufacturing a 3C-SiC self-supporting substrate according to an embodiment of the present invention is shown.

[0045] Figure 3 The in-plane XRD (In Plane XRD) analysis results of the 3C-SiC single crystal epitaxial substrate obtained in the examples are shown. DETAILED DESCRIPTION OF THE INVENTION

[0046] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0047] As described above, there is a need to find a method for manufacturing a 3C-SiC single crystal epitaxial substrate, a method for manufacturing a 3C-SiC self-supporting substrate, and a 3C-SiC single crystal epitaxial substrate that can obtain a large-diameter 3C-SiC self-supporting substrate through a simple manufacturing process.

[0048] The inventors of the present application repeatedly and intensively studied the above problems, and as a result, found that a 3C-SiC single crystal epitaxial substrate that can obtain a large-diameter 3C-SiC self-supporting substrate through a simple manufacturing process can be manufactured by a method for manufacturing a 3C-SiC single crystal epitaxial substrate. Furthermore, the present invention was completed. The method for manufacturing a 3C-SiC single crystal epitaxial substrate is characterized in that it includes the following steps: a hydrogen baking step of removing the natural oxide film on the surface of the single crystal silicon substrate by annealing the single crystal silicon substrate in a hydrogen atmosphere; an epitaxial step of performing carbonization treatment on the surface of the single crystal silicon substrate after the hydrogen baking step to generate nuclei of SiC, and further epitaxially growing a 3C-SiC single crystal film starting from the generated nuclei to obtain a 3C-SiC single crystal epitaxial substrate; and a diffusion step of heating the 3C-SiC single crystal epitaxial substrate to a temperature lower than the melting point of Si in a gas atmosphere containing carbon, so that Si in the single crystal silicon substrate solid-state diffuses to the interface between the 3C-SiC single crystal film and the single crystal silicon substrate, and the diffused Si reacts with C reaching the interface to further grow SiC, thereby forming a void layer at the interface between the single crystal silicon substrate and the 3C-SiC single crystal film, and the void layer has voids generated at the diffusion traces of Si.

[0049] In addition, the inventors of the present application repeatedly and intensively studied the above problems, and as a result, found that a large-diameter 3C-SiC self-supporting substrate can be obtained through a simple manufacturing process by a method for manufacturing a 3C-SiC self-supporting substrate, and thus completed the present invention. The method for manufacturing a 3C-SiC self-supporting substrate is characterized in that it includes the following steps: a separation step, by cooling the 3C-SiC single crystal epitaxial substrate manufactured by the manufacturing method described above, peeling the 3C-SiC single crystal epitaxial substrate along the void layer, and separating the 3C-SiC single crystal film from the single crystal silicon substrate, thereby forming a 3C-SiC self-supporting substrate.

[0050] Furthermore, the inventors of the present application repeatedly and intensively studied the above problems, and as a result, found that a large-diameter 3C-SiC self-supporting substrate can be obtained through a simple manufacturing process by a 3C-SiC single crystal epitaxial substrate, and thus completed the present invention. The 3C-SiC single crystal epitaxial substrate is characterized in that it includes: a single crystal silicon substrate, and a 3C-SiC single crystal film of an epitaxial structure provided on the single crystal silicon substrate, and the single crystal silicon substrate has a void layer at the interface with the 3C-SiC single crystal film, and the void layer includes a collection of voids generated by the detachment of Si.

[0051] Hereinafter, an explanation will be given with reference to the drawings.

[0052] Hereinafter, while referring to Figure 1 and Figure 2 an explanation will be given of the manufacturing method of the 3C-SiC single crystal epitaxial substrate 1, the manufacturing method of the 3C-SiC self-supporting substrate 9, and the configuration of the 3C-SiC single crystal epitaxial substrate 1 according to the embodiments of the present invention.

[0053] First, with reference to Figure 1 an explanation will be given of the outline of the configuration of the 3C-SiC single crystal epitaxial substrate 1 according to the embodiments of the present invention.

[0054] As Figure 1 shown, the 3C-SiC single crystal epitaxial substrate 1 includes a single crystal silicon substrate 3 and a 3C-SiC single crystal film 5 of an epitaxial structure provided on the single crystal silicon substrate.

[0055] The single crystal silicon substrate 3 is a substrate that serves as a base when the 3C-SiC single crystal film 5 is formed by epitaxial growth. The thickness of the single crystal silicon substrate 3 depends on the thickness of the 3C-SiC single crystal film 5, but for example, as long as it is a thickness such that the single crystal silicon substrate 3 does not bend or break due to stress caused by the difference in lattice constants between silicon and SiC when the 3C-SiC single crystal film 5 is formed by epitaxial growth.

[0056] The diameter of the single-crystalline silicon substrate 3 is at least greater than or equal to the diameter of the 3C-SiC single-crystalline film 5. However, since the larger the diameter of the single-crystalline silicon substrate 3, the larger the diameter of the 3C-SiC single-crystalline film 5 that can be set, it is preferably set to 200 mm or more in diameter, and more preferably 300 mm or more in diameter.

[0057] In addition, the single-crystalline silicon substrate 3 has a void layer 7 at the interface with the 3C-SiC single-crystalline film. The void layer 7 contains a collection of voids generated by the detachment of Si.

[0058] Since the void layer 7 has a collection of voids, it becomes more brittle compared to other parts. Therefore, stress can be applied by cooling or the like, and thereby the 3C-SiC single-crystalline epitaxial substrate 1 can be peeled along the void layer 7, so that the 3C-SiC single-crystalline film 5 can be easily separated from the single-crystalline silicon substrate 3.

[0059] Therefore, the 3C-SiC single-crystalline epitaxial substrate 1 can obtain a large-diameter 3C-SiC self-supporting substrate through a simple manufacturing process.

[0060] In addition, in the following description, the part of the single-crystalline silicon substrate 3 other than the void layer 7 is referred to as the base 11. In addition, the density of the voids in the void layer 7 and the thickness of the void layer are appropriately set within a range in which the 3C-SiC single-crystalline epitaxial substrate 1 can be easily peeled by cooling.

[0061] The 3C-SiC single-crystalline film 5 is a film having an epitaxial structure. The lower limit of the thickness of the 3C-SiC single-crystalline film 5 is, for example, such that it can maintain its shape without bending or breaking even after being separated from the single-crystalline silicon substrate 3 and will not disappear due to polishing or etching or the like when forming a device or the like thereafter. The upper limit of the thickness is such that when forming a device or the like thereafter, not many unused parts will be generated and the cost will not become high. In addition, the diameter of the 3C-SiC single-crystalline film 5 is less than or equal to the diameter of the single-crystalline silicon substrate 3.

[0062] Next, refer to Figure 2 The manufacturing method of the 3C-SiC single-crystalline epitaxial substrate 1 and the manufacturing method of the 3C-SiC self-supporting substrate 9 according to the embodiments of the present invention will be described.

[0063] First, as Figure 2As shown in (a) of , a single-crystalline silicon substrate 3 is prepared as a substrate for epitaxial growth of a 3C-SiC single-crystalline film 5. The surface orientation of the prepared single-crystalline silicon substrate 3 is determined according to the surface orientation of the predetermined 3C-SiC single-crystalline film 5 to be grown. For example, it is the (111) plane, and it can also be the (110) plane or the (100) plane. The thickness of the single-crystalline silicon substrate 3 is selected to be a thickness that will not bend or break during the growth process according to the thickness of the predetermined 3C-SiC single-crystalline film 5 to be grown. The diameter of the single-crystalline silicon substrate 3 is set to be greater than or equal to the diameter of the 3C-SiC single-crystalline film 5 to be grown.

[0064] Next, the prepared single-crystalline silicon substrate 3 is placed in a growth furnace for epitaxial growth of a 3C-SiC single-crystalline film 5, such as a reduced-pressure CVD apparatus (RP-CVD apparatus), and the natural oxide film on the surface is removed by performing H2 annealing on the single-crystalline silicon substrate 3 in a hydrogen atmosphere (hydrogen baking process). The reason is that if the natural oxide film remains, when the 3C-SiC single-crystalline film 5 is epitaxially grown on the single-crystalline silicon substrate 3, it becomes impossible to form nuclei of SiC.

[0065] The H2 annealing temperature at this time is preferably set under the condition of 1000 °C or higher and 1200 °C or lower. By setting the temperature to 1000 °C or higher, the hydrogen baking process for preventing the remaining of the natural oxide film can be completed in a short time. In addition, by setting the temperature to 1200 °C or lower, the occurrence of slip can be surely suppressed. Regarding the pressure and time of the H2 annealing at this time, as long as the natural oxide film can be removed, there is no particular limitation.

[0066] Next, as shown in (b) of Figure 2 The surface of the single-crystalline silicon substrate 3 after the hydrogen baking process is subjected to a carbonization treatment to generate nuclei of SiC, and further, the 3C-SiC single-crystalline film 5 is heteroepitaxially grown starting from the generated nuclei (epitaxial process).

[0067] Specifically, first, in order to carbonize the surface of the single-crystalline silicon substrate 3 to form nuclei of SiC, a carbonization gas such as propane gas as a source gas is introduced into the RP-CVD apparatus while the temperature inside the apparatus is slowly raised from a range of 300 °C or higher and 950 °C or lower to a range of 1000 °C or higher and less than 1200 °C.

[0068] Next, the source gas is switched to a gas containing C and Si such as trimethylsilane gas, and the 3C-SiC single-crystalline film 5 is epitaxially grown starting from the carbonized nuclei. The heating rate during the epitaxial growth of SiC is preferably in the range of 0.5 to 5 °C / min, and more preferably about 1 °C / min.

[0069] In addition, the thickness of the 3C-SiC single crystal film 5 to be grown in the epitaxial process may be thinner than the final target value. The reason is that the 3C-SiC single crystal film 5 will be grown in subsequent processes.

[0070] Next, as shown in (c) of Figure 2 , the 3C-SiC single crystal epitaxial substrate is heated to a temperature lower than the melting point of Si in a carbon-containing gas atmosphere, so that Si in the single crystal silicon substrate 3 solid-state diffuses to the interface between the 3C-SiC single crystal film 5 and the single crystal silicon substrate 3. Through the solid-phase reaction of the diffused Si and C reaching the interface, SiC is further grown. Thus, a void layer 7 is formed at the interface between the 3C-SiC single crystal film 5 and the single crystal silicon substrate 3 in the single crystal silicon substrate 3. The void layer 7 has voids generated at the diffusion traces of Si (diffusion process).

[0071] Specifically, for example, while introducing a gas containing C and Si such as trimethylsilane gas into the RP-CVD apparatus at a temperature of 1000 °C or higher and lower than the melting point of silicon, the 3C-SiC single crystal film 5 is grown. At this time, if the raw material contains not only C but also Si, the 3C-SiC single crystal film 5 can be grown by a gas-phase reaction on the surface, and further can be grown by a solid-phase reaction of carbon atoms reaching the interface between the 3C-SiC single crystal film 5 and the single crystal silicon substrate 3 and Si diffusing from the Si substrate to the interface.

[0072] In addition, in the diffusion process, through the solid-phase reaction, voids are generated at the interface between the 3C-SiC single crystal film 5 and the single crystal silicon substrate 3 in the single crystal silicon substrate 3 after Si detachment, and the void layer 7 is formed by the aggregation of these voids.

[0073] Thus, it is possible to grow SiC using the single crystal silicon substrate 3 as a Si source by not only using a gas-phase reaction but also using a solid-phase reaction, and it is also possible to fabricate the 3C-SiC single crystal epitaxial substrate 1 having the void layer 7 as shown in Figure 1 , in which, as the void layer 7, voids exist at the interface between the 3C-SiC single crystal film 5 and the single crystal silicon substrate 3 in the single crystal silicon substrate 3.

[0074] In addition, it is preferable to perform the epitaxial process and the diffusion process within a pressure range of 133.322 Pa (1 Torr.) or more and 13332.2 Pa (100 Torr.) or less. Specifically, it is preferable to set the pressure in the RP-CVD apparatus during the epitaxial process and the diffusion process to 133.322 Pa or more and 13332.2 Pa or less.

[0075] By setting the pressure in the RP-CVD apparatus to 133.322 Pa or more, the epitaxial process and the diffusion process can be carried out without using a special decompression device. In addition, by setting the pressure in the RP-CVD apparatus to 13332.2 Pa or less, the epitaxial growth of 3C-SiC in the epitaxial process and the diffusion of SiC in the diffusion process can be promoted.

[0076] In addition, if the pressure in the RP-CVD apparatus during the diffusion process is set to a pressure of about 666.612 Pa (5 Torr.), the growth of voids can be promoted, and the growth rate of SiC will also increase, so it is preferable. In addition, the time of the diffusion process is the time to obtain a 3C-SiC single crystal film 5 and a void layer 7 with a desired thickness.

[0077] The above is the description of the manufacturing method of the 3C-SiC single crystal epitaxial substrate 1.

[0078] Next, by cooling the 3C-SiC single crystal epitaxial substrate 1 manufactured by this manufacturing method, the 3C-SiC single crystal epitaxial substrate 1 is peeled off along the void layer 7, and as shown in (d) of Figure 2 the 3C-SiC single crystal film 5 is separated from the single crystal silicon substrate 3 to produce a 3C-SiC self-supporting substrate 9 (separation process).

[0079] Specifically, in the diffusion process, after growing a 3C-SiC single crystal film 5 with a target specified thickness, the supply of the source gas is stopped, and then the temperature inside the RP-CVD apparatus is lowered, etc., to cool the 3C-SiC single crystal epitaxial substrate 1.

[0080] Due to the temperature drop at this time, the 3C-SiC single crystal film 5 is separated from the base 11 of the single crystal silicon substrate 3. In particular, if it is rapidly passed through the temperature range around 400 °C, the 3C-SiC single crystal epitaxial substrate 1 will be rapidly peeled off starting from the void layer 7, and thus the 3C-SiC single crystal film 5 will be separated from the base 11 of the single crystal silicon substrate 3.

[0081] As long as the 3C-SiC single crystal epitaxial substrate 1 can be peeled off to separate the 3C-SiC single crystal film 5 from the single crystal silicon substrate 3, the specific treatment during the temperature drop is not particularly limited, and two types of treatments such as what is called a cooling process and a low-temperature treatment can be exemplified.

[0082] The cooling process refers to the following treatment: after growing a 3C-SiC single crystal film 5 with a target specified thickness, the 3C-SiC single crystal epitaxial substrate 1 is naturally cooled to 500 °C, held at 500 °C for 30 seconds to 3 minutes, and then cooled to 200 °C at 4 - 5 °C / min and taken out.

[0083] The low-temperature treatment refers to the following treatment: after growing a 3C-SiC single-crystal film 5 with a specified thickness of the target, the 3C-SiC single-crystal epitaxial substrate 1 is directly put into a furnace at 200°C. After being treated at 200°C for 2 hours, it is heated to 500°C at a rate of 4 - 5°C / min, held at 500°C for 30 seconds, then directly taken out of the furnace and naturally cooled at room temperature.

[0084] In addition, after peeling, the 3C-SiC single-crystal film 5 is still on the base 11 of the single-crystalline silicon substrate 3, so it can be directly taken out from the RP-CVD apparatus. After taking out, the base 11 of the single-crystalline silicon substrate 3 can be separated from the 3C-SiC single-crystal film 5.

[0085] Furthermore, the 3C-SiC single-crystal film 5 can be regrown by using the base 11 of the separated single-crystalline silicon substrate 3 to perform the baking process, epitaxial process, and diffusion process again. In addition, at this time, the surface of the base 11 of the single-crystalline silicon substrate 3 can be directly used after peeling, and the surface can also be polished and cleaned once according to the size or density of the pores in the pore layer 7.

[0086] The above is the description of the manufacturing method of the 3C-SiC self-supporting substrate 9.

[0087] Thus, by using an RP-CVD apparatus or the like as a growth apparatus capable of handling large-diameter substrates, after removing the natural oxide film on the surface of a single-crystalline silicon substrate 3 with a diameter of 300 mm or more by a hydrogen baking process, carbonization treatment is performed, and then heteroepitaxial growth of a 3C-SiC single-crystal film 5 is carried out on the single-crystalline silicon substrate 3. Further, it is set to a high temperature at which the single-crystalline silicon substrate 3 does not melt, and a gas containing carbon is circulated to further grow the 3C-SiC single-crystal film 5 by solid-state diffusion of the single-crystalline silicon substrate 3, thereby fabricating a 3C-SiC epitaxial substrate having a plurality of pores at the interface between the 3C-SiC single-crystal film 5 and the single-crystalline silicon substrate 3. Thus, peeling can be implemented by using these pores in subsequent cooling treatment and the like.

[0088] Therefore, in the manufacturing method of the 3C-SiC self-supporting substrate 9 of the present invention, using the single-crystalline silicon substrate 3 as a Si supply source, heteroepitaxial growth of the 3C-SiC single-crystal film 5 is performed by solid-state diffusion. After forming the pore layer 7, by removing the single-crystalline silicon substrate 3, a large-diameter 3C-SiC self-supporting substrate 9 with a diameter of 200 mm or 300 mm can be obtained.

[0089] Examples

[0090] Hereinafter, examples are given to specifically illustrate the present invention, but these examples do not limit the present invention.

[0091] The 3C-SiC single-crystal epitaxial substrate 1 is manufactured by the manufacturing method of the 3C-SiC single-crystal epitaxial substrate of the present invention, and further attempts are made to manufacture the 3C-SiC self-supporting substrate 9. The specific steps are as described below.

[0092] First, as the single-crystal silicon substrate 3, a boron-doped low-resistance single-crystal silicon wafer with a diameter of 300 mm, a surface plane orientation of (111), and a resistivity of 0.1 Ω·cm is prepared.

[0093] Next, the wafer is placed on the pedestal in the reaction furnace of the RP-CVD apparatus. As the hydrogen baking process, H2 annealing is performed at 1080 °C for 1 minute. Next, as the epitaxial process, after the temperature in the furnace is cooled to 300 °C, while increasing the temperature to 1130 °C at a heating rate of 1 °C / sec, propane gas is introduced to form nuclei of SiC, and further trimethylsilane gas is introduced to form the subsequent 3C-SiC single-crystal film 5. The growth pressure at this time is uniformly set to 666.612 Pa (5 Torr).

[0094] Furthermore, after the temperature in the reaction furnace reaches 1130 °C, it is maintained for 10 hours. As the diffusion process, the growth of the 3C-SiC single-crystal film 5 and the formation of the vacancy layer 7 are performed. Then, after the film thickness of the 3C-SiC single-crystal film 5 reaches 100 μm, the supply of the source gas is stopped, and it is naturally cooled to 500 °C and maintained at 500 °C for 120 seconds, and then cooled to 200 °C at 5 °C / min (cooling process).

[0095] Then, the cooled 3C-SiC single-crystal epitaxial substrate is taken out from the reaction furnace, and the crystal structure of the 3C-SiC single-crystal epitaxial substrate is confirmed by XRD with the 3C-SiC single-crystal film 5 and the single-crystal silicon substrate 3 arranged in-plane in the original state without deviation. The results are as Figure 3 shown. The peak of 3C-SiC(220) parallel to Si(220) can be confirmed, and it is confirmed that a single-crystal 3C-SiC film has grown on the single-crystal silicon substrate 3.

[0096] In addition, the 3C-SiC single-crystal epitaxial substrate 1 taken out from the reaction furnace can be separated into the 3C-SiC single-crystal film 5 (3C-SiC self-supporting substrate 9) and the base 11 of the single-crystal silicon substrate 3 even without performing additional cooling or other treatments. Therefore, it can also be confirmed that peeling has occurred during the cooling process before taking out from the reaction furnace.

[0097] As described above, according to the embodiment of the present invention, the 3C-SiC single-crystal epitaxial substrate 1 can be manufactured, and the manufactured 3C-SiC single-crystal epitaxial substrate 1 can be peeled off to manufacture the 3C-SiC self-supporting substrate 9.

[0098] The present invention is not limited to the above-described embodiments. The above-described embodiments are examples, and any solution that has a substantially identical composition and exhibits the same effect as the technical concept described in the claims of the present invention is included within the technical scope of the present invention.

Claims

1. A manufacturing method of a 3C-SiC single crystal epitaxial substrate, characterized in that, It includes the following steps: A hydrogen baking step of annealing a single-crystalline silicon substrate in a hydrogen atmosphere to remove the native oxide film on the surface of the single-crystalline silicon substrate. An epitaxial growth step of performing carbonization treatment on the surface of the single-crystalline silicon substrate after the hydrogen baking step to generate nuclei of SiC, and further epitaxially growing a 3C-SiC single-crystalline film starting from the generated nuclei to obtain a 3C-SiC single-crystalline epitaxial substrate. And A diffusion step of heating the 3C-SiC single-crystalline epitaxial substrate in a gas atmosphere containing carbon to a temperature lower than the melting point of Si, causing solid-state diffusion of Si in the single-crystalline silicon substrate to the interface between the 3C-SiC single-crystalline film and the single-crystalline silicon substrate, and causing a solid-phase reaction between the diffused Si and C reaching the interface to further grow SiC, thereby forming a void layer at the interface between the single-crystalline silicon substrate and the 3C-SiC single-crystalline film, and the void layer has voids generated at the diffusion traces of Si.

2. The manufacturing method of the 3C-SiC single crystal epitaxial substrate according to claim 1, characterized in that The epitaxial growth step and the diffusion step are carried out in a pressure range of 133.322 Pa or more and 13332.2 Pa or less.

3. A manufacturing method of a 3C-SiC self-supporting substrate, characterized in that, It includes the following steps: A separation step of cooling the 3C-SiC single-crystalline epitaxial substrate manufactured by the method for manufacturing a 3C-SiC single-crystalline epitaxial substrate according to claim 1 or 2, thereby peeling the 3C-SiC single-crystalline epitaxial substrate along the void layer and separating the 3C-SiC single-crystalline film from the single-crystalline silicon substrate to manufacture a 3C-SiC self-supporting substrate.

4. A 3C-SiC single crystal epitaxial substrate, characterized in that, It includes: A single-crystalline silicon substrate, and A 3C-SiC single-crystalline film of an epitaxial structure provided on the single-crystalline silicon substrate. The single-crystalline silicon substrate has a void layer at the interface with the 3C-SiC single-crystalline film, and the void layer contains a collection of voids generated by the shedding of Si.

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