METHOD FOR MANUFACTURING RECYCLED SiC SUBSTRATE AND LAMINATE STRUCTURE

Abstract

To provide a new recycled technology for SiC substrates used as growth base substrates for group III nitrides.SOLUTION: A method for manufacturing a recycled SiC substrate comprises: (a) a process for preparing a SiC substrate with group III nitrides on the main surface; (b) a process for supplying halogen-containing gas to the SiC substrate to remove group III nitrides from the main surface; and (c) a process for reforming the main surface by supplying hydrogen-containing gas to the SiC substrate from which group III nitrides have been removed.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a recycled SiC substrate and a method for manufacturing a laminated structure.

Background Art

[0002] Group III nitrides such as gallium nitride (GaN) are used as materials for manufacturing semiconductor devices such as light-emitting devices and transistors. As a growth substrate for epitaxially growing Group III nitrides, a sapphire substrate, a silicon carbide (SiC) substrate, or the like is used.

[0003] Due to various circumstances, there may be a case where the growth substrate once used for the growth of Group III nitrides is recycled so that it can be used again for the growth of Group III nitrides (for example, see Patent Document 1 regarding the recycling of sapphire substrates).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] One object of the present invention is to provide a novel recycling technique for SiC substrates used as growth substrates for Group III nitrides.

Means for Solving the Problems

[0006] According to one aspect of the present invention, (a) preparing an SiC substrate having a Group III nitride attached to a main surface; (b) supplying a halogen-containing gas to the SiC substrate to remove the Group III nitride from the main surface; (c) Supplying a hydrogen-containing gas to the SiC substrate from which the group III nitride has been removed to modify the main surface; Method for manufacturing a regenerated SiC substrate having is provided.

[0007] According to another aspect of the present invention, (a) Preparing a SiC substrate having a group III nitride attached to a main surface; (b) Supplying a halogen-containing gas to the SiC substrate to remove the group III nitride from the main surface; (c) Supplying a hydrogen-containing gas to the SiC substrate from which the group III nitride has been removed to modify the main surface; (d) Growing crystals on the modified main surface; Method for manufacturing a laminated structure having is provided.

Advantages of the Invention

[0008] A novel regeneration technique for a SiC substrate used as a growth base substrate for a group III nitride is provided.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

DETAILED DESCRIPTION OF THE INVENTION

[0010] <One Embodiment> A method for manufacturing a regenerated SiC substrate according to an embodiment of the present invention will be described. The method for manufacturing a regenerated SiC substrate according to this embodiment includes a step of preparing a SiC substrate having a group III nitride attached to the main surface, a step of supplying a halogen-containing gas to the SiC substrate to remove the group III nitride from the main surface, and a step of supplying a hydrogen-containing gas to the SiC substrate from which the group III nitride has been removed to modify the main surface.

[0011] Here, the group III nitride preferably contains indium (In), aluminum (Al), or gallium (Ga) as a group III element, and is represented by the composition formula of In x Al y Ga (1-x-y) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, x + y ≦ 1).

[0012] Figs. 1(a) to 2(b) are schematic diagrams showing the flow of the regeneration process of the SiC substrate 10. Fig. 3 is a timing chart of temperature and gas supply in the regeneration process of the SiC substrate 10. Fig. 1(a) is a schematic diagram showing the step of preparing a SiC substrate 10 (laminated structure 100) on which a group III nitride is attached (a layer 20 made of a group III nitride is formed (deposited)) on the main surface 11. The SiC substrate 10 is typically prepared in the form of a laminated structure 100 having a SiC substrate 10 and a layer 20 composed of a group III nitride epitaxially grown on the main surface 11 of the SiC substrate 10. In the present embodiment, the term "main surface" related to the SiC substrate 10 means the upper surface of the SiC substrate 10 (the surface that is the growth base of the layer 20), rather than the crystal growth surface of the layer 20 (the outermost surface of the laminated structure 100).

[0013] The layer 20 is typically formed over the entire surface of the main surface 11 of the SiC substrate 10. The structure of the layer 20 is not particularly limited, and it may be a single-layer structure, a laminated structure including a plurality of layers, or may have irregularities for forming a semiconductor element. The layer 20 may include, for example, a GaN layer, and in an embodiment including a GaN layer, a buffer layer (for example, an AlN layer) may be included between the SiC substrate 10 and the GaN layer. The thickness of the layer 20 is, for example, 100 nm or more and 5000 nm or less.

[0014] Fig. 1(b) is a schematic diagram showing the step of loading the laminated structure 100 into the processing apparatus 200 and performing a pretreatment prior to the process of removing the layer 20. In the present embodiment, a film-forming apparatus capable of performing a process of growing a group III nitride on the SiC substrate 10 is used as the processing apparatus 200 for performing a process of removing the layer 20 (group III nitride) to regenerate the SiC substrate 10. For example, a metal-organic chemical vapor deposition (MOVPE) apparatus is used.

[0015] As the processing device 200, either a hot-wall type or a cold-wall type may be used. However, from the viewpoint of sufficiently increasing the processing temperature of various processes in the following reproduction process and further enhancing the effects of the present embodiment, it is preferable to use the cold-wall type processing device 200. Hereinafter, the cold-wall type processing device 200 will be exemplified.

[0016] A susceptor 220 is provided in the processing container 210 of the processing device 200. The stacked structure 100 is placed on the susceptor 220. The susceptor 220 has a heater 230, and the heater 230 heats the stacked structure 100 to a predetermined processing temperature. A gas supply mechanism 240 supplies a processing gas 250 used for each process into the processing container 210.

[0017] After the stacked structure 100 is carried into the processing container 210, as a pretreatment prior to the process of removing the layer 20, a step of annealing the SiC substrate 10 in a reducing atmosphere is performed. Specifically, for example, heating is performed in a hydrogen gas (H2 gas) atmosphere to perform hydrogen annealing (see period P1 in FIG. 3). In the annealing process, the processing temperature is, for example, 900°C or higher and 1300°C or lower, and the processing time is, for example, 10 seconds or longer and 600 seconds or shorter.

[0018] By the annealing process, an oxide film (such as a natural oxide film) formed on the surface of the layer 20 (of the group III nitride) can be removed, and the subsequent removal of the group III nitride can proceed reliably and efficiently.

[0019] FIG. 2(a) is a schematic diagram showing a step of supplying a halogen-containing gas to the SiC substrate 10 and removing the layer 20 (group III nitride) from the main surface 11 of the SiC substrate 10. Specifically, for example, chlorine gas (Cl2 gas) is used as the halogen-containing gas, and dry etching of the layer 20 is performed under predetermined processing conditions (see period P2 in FIG. 3). In the removal process of the layer 20, the processing temperature is, for example, 800°C or higher and 1100°C or lower (preferably 800°C or higher and 1000°C or lower), and the processing time is, for example, 120 seconds or longer and 720 seconds or shorter. As the atmosphere gas, for example, nitrogen gas (N2 gas) is used.

[0020] In the removal process of layer 20, by removing layer 20 with its entire thickness, the entire surface of the main surface 11 of the SiC substrate 10 is exposed. Then, silicon (Si) is desorbed from the main surface 11 exposed by removing layer 20, and a Si-deficient region 12 is formed on the main surface 11 (preferably over the entire area of the main surface 11). It is understood that SiC constituting the exposed main surface 11 reacts with the halogen-containing gas to generate a silicon halide gas, and thus Si is desorbed to form the Si-deficient region 12. The carbon (C) remaining in the Si-deficient region 12 may be graphitized.

[0021] The removal process of layer 20 is preferably performed under conditions that enable the formation of the Si-deficient region 12 over the entire area of the main surface 11. Such conditions include, for example, the processing temperature, the processing time, and the like. For example, by setting the processing temperature to a temperature of 800°C or higher and 1100°C or higher (preferably 800°C or higher and 1000°C or lower) as described above, it becomes possible to form the Si-deficient region 12 over substantially the entire area of the main surface 11 (for example, an area of 90% or more).

[0022] From the viewpoint of suitably performing the removal of the group III nitride and the formation of the Si-deficient region 12, as the halogen-containing gas, at least any one gas selected from the group consisting of F2 gas, Cl2 gas, Br2 gas, I2 gas, NF3 gas, ClF3 gas, HF gas, HCl gas, HBr gas, and HI gas may be used.

[0023] FIG. 2(b) is a schematic diagram showing a step of supplying a hydrogen-containing gas to the SiC substrate 10 from which the layer 20 (III-nitride) has been removed and modifying the main surface 11. Specifically, for example, ammonia gas (NH3 gas) is used as the hydrogen-containing gas, and the main surface 11 is modified under predetermined processing conditions (see the period P3 in FIG. 3). In the modification process of the main surface 11, the processing temperature is, for example, 900°C or higher and 1200°C or lower (preferably 1100°C or higher and 1200°C or lower), and the processing time is, for example, 150 seconds or longer and 600 seconds or shorter. As the ambient gas, for example, N2 gas or H2 gas is used. The processing temperature in the modification process of the main surface 11 is preferably relatively high and higher than the processing temperature in the removal process of the layer 20. Note that the ambient gas may be switched so that N2 gas is first used and then H2 gas is used. By finishing the treatment in an H2 gas atmosphere, the modification of the main surface 11 (the purification of SiC constituting the main surface 11) can be performed more preferably.

[0024] In the modification process of the main surface 11, the C component is desorbed from the Si-deficient region 12, and the Si-deficient region 12 is removed from the main surface 11 (preferably from the entire area of the main surface 11). It is understood that C contained in the Si-deficient region 12 on the main surface 11 reacts with the hydrogen-containing gas to generate a hydrocarbon gas, so that C is desorbed and the Si-deficient region 12 is removed.

[0025] The modification process of the main surface 11 is preferably performed under conditions that enable the removal of the Si-deficient region 12 from the entire area of the main surface 11. These conditions include, for example, the processing temperature, the processing time, and the like. For example, by setting the processing temperature in the modification process of the main surface 11 to a temperature higher than the processing temperature in the removal process of the layer 20 as described above and 900°C or higher and 1200°C or higher (preferably 1100°C or higher and 1200°C or lower), the Si-deficient region 12 can be removed from substantially the entire area (for example, 90% or more of the area) of the main surface 11.

[0026] From the viewpoint of suitably removing the Si-deficient region 12, as the hydrogen-containing gas, at least any one gas selected from the group consisting of H2 gas, NH3 gas, N2H2 gas, N2H4 gas, and N3H8 gas may be used.

[0027] By performing a process of reforming the main surface 11 to remove the Si-deficient region 12, a regenerated SiC substrate 10a having a clean main surface 11 made of SiC is obtained. Thereafter, the SiC substrate 10 (regenerated SiC substrate 10a) is cooled to a predetermined temperature. In the present embodiment, as described above, the regeneration of the SiC substrate 10, that is, the production of the regenerated SiC substrate 10a is performed.

[0028] The process of removing the layer 20 (FIG. 2(a)) and the process of reforming the main surface 11 (FIG. 2(b)) are performed continuously in the same processing container 210 (without taking out the SiC substrate 10 from the processing container 210 and exposing it to the atmosphere in the middle). Thereby, it becomes possible to improve the productivity of the regenerated SiC substrate 10a. Further, it becomes possible to avoid contamination of the SiC substrate 10 due to atmospheric exposure or the like. It is also preferable to continuously perform the annealing process (FIG. 1(b)), which is a pretreatment, and the process of removing the layer 20 (FIG. 2(a)) in the same processing container 210.

[0029] After growing group III nitride on a new SiC substrate 10, a test of regenerating it by the method of the present embodiment was conducted. The thickness of the new SiC substrate 10 was 0.4935 mm (analysis error ±0.0003 mm), and the thickness of the regenerated SiC substrate 10a was 0.4936 mm (analysis error ±0.0003 mm). It was found that, according to the present embodiment, the difference between the thickness of the SiC substrate 10 before regeneration and the thickness of the SiC substrate 10 (regenerated SiC substrate 10a) after regeneration can be suppressed within ±0.0003 mm (as a first standard), that is, the thickness of the regenerated SiC substrate 10a can be maintained substantially equal to the thickness of the SiC substrate 10 before regeneration.

[0030] In the method for regenerating the SiC substrate 10 according to this embodiment, in this way, compared with the conventional regeneration method by polishing or the like, the SiC substrate 10 can be regenerated while suppressing the reduction in the thickness of the SiC substrate 10 caused by the regeneration process. In this embodiment, although the Si-deficient region 12 is generated and removed on the main surface 11 of the SiC substrate 10, the variation in the thickness of the SiC substrate 10 accompanying the removal of the Si-deficient region 12 remains much smaller than the analysis error of the thickness measurement of the SiC substrate 10.

[0031] Also, growing (specifically, laminating a high electron mobility transistor structure) and then removing group III nitrides on the SiC substrate 10 under the same conditions, starting from a new SiC substrate 10, a test was conducted by repeating the method of this embodiment 18 times (that is, performing 18 regenerations). The film thickness and Al composition of the AlGaN barrier layer grown on the new SiC substrate 10 were 21.3 nm and 0.277 respectively, and the film thickness of the GaN cap layer was 3.4 nm. For the growth in 18 regenerations, the film thickness and Al composition of the AlGaN barrier layer obtained were values within the ranges of 21.1 nm to 21.6 nm and 0.271 to 0.276 respectively for the Al composition, and the film thickness of the GaN cap layer was a value within the range of 3.3 nm to 3.5 nm. Thus, according to the method of this embodiment, even if regeneration is repeated, the growth of group III nitrides can be performed almost in the same manner, and a regenerated SiC substrate 10a of a certain quality can be obtained repeatedly. Since the thickness of the SiC substrate 10 does not substantially change even if regeneration is repeated, it is not necessary to change (adjust) the growth conditions of the group III nitrides grown on the SiC substrate 10 according to the reduction in the SiC substrate thickness that occurs in the conventional regeneration method by polishing or the like, and it becomes easy to repeatedly grow group III nitrides of a certain quality.

[0032] As described above, the method for manufacturing a regenerated SiC substrate according to this embodiment includes a step of preparing a SiC substrate having a group III nitride attached to the main surface, a step of supplying a halogen-containing gas to the SiC substrate to remove the group III nitride from the main surface, and a step of supplying a hydrogen-containing gas to the SiC substrate from which the group III nitride has been removed to modify the main surface.

[0033] In the step of removing the group-III nitride from the main surface, a Si-deficient region is formed on the main surface, and in the step of modifying the main surface, the Si-deficient region is removed from the main surface. The Si-deficient region is preferably formed over the entire area of the main surface and removed from the entire area of the main surface.

[0034] By being able to perform the regeneration of the SiC substrate by dry etching as in the present embodiment, rather than by means of polishing or wet etching, it becomes possible to enhance the productivity in manufacturing a regenerated SiC substrate.

[0035] However, according to the intensive research by the inventors of the present application, it has been found that simply performing dry etching to remove the group-III nitride may reduce the quality of the crystal to be epitaxially grown on the regenerated SiC substrate (for example, the number of defects appearing on the crystal surface increases). When performing dry etching using a halogen-containing gas, Si may desorb from the main surface of the SiC substrate exposed by the removal of the group-III nitride, and thereby, a "Si-deficient region" containing graphene or the like may be generated on the main surface. This Si-deficient region is considered to be a factor that degrades the quality of the crystal epitaxially grown on the main surface of the regenerated SiC substrate.

[0036] On the other hand, according to the intensive research by the inventors of the present application, the state of the new main surface (refreshed main surface) obtained through the formation and removal of the Si-deficient region has been found to have improved crystal quality and be suitable as a growth substrate for epitaxial growth, as compared with the state of the main surface that has not undergone this process, that is, the original main surface considered to contain SiC crystals damaged in the processing steps during substrate manufacturing.

[0037] According to the embodiment of the present application, in the step of removing the group-III nitride from the main surface, a Si-deficient region is intentionally formed on the main surface of the SiC substrate, and in the subsequent step of modifying the main surface, the Si-deficient region is removed from the main surface, whereby it becomes possible to obtain a high-quality regenerated SiC substrate.

[0038] The processing apparatus 200 according to the present embodiment is also a film forming apparatus, and before the regeneration process of the SiC substrate 10, a growth process of group III nitride may be performed. As shown in FIG. 1(b), due to the growth process, deposits 260 containing group III nitride may adhere to the inner wall of the processing vessel 210 at the time of starting the regeneration process of the SiC substrate 10. Note that the deposits 260 may adhere over the entire inner wall of the processing vessel 210, but here, for simplicity of illustration, the deposits 260 are illustrated as one granule.

[0039] In order to remove the deposits containing group III nitride, that is, to clean the inside of the processing vessel of the film forming apparatus, generally, a cleaning process of supplying a halogen-containing gas into the processing vessel is performed. As shown in FIG. 2(a), in the present embodiment, the process of removing the layer 20 (group III nitride) from the main surface 11 of the SiC substrate 10 supplies a halogen-containing gas into the processing vessel 210, so it also functions as a cleaning process and has the effect of removing the deposits 260 adhering to the inner wall of the processing vessel 210.

[0040] Therefore, it can be said that the step of removing the layer 20 (and the step of modifying the main surface 11) is performed in parallel with the step of cleaning the inside of the processing vessel 210. Note that the processing conditions for the process of removing the layer 20 do not have to be optimal as the processing conditions for the process of cleaning the inside of the processing vessel 210. In order to make the effect of the cleaning process more reliable, the step of removing the layer 20 (and the step of modifying the main surface 11) and the step of cleaning the inside of the processing vessel 210 (under processing conditions suitable for cleaning, additionally, before or after the step of removing the layer 20) may be performed continuously.

[0041] By performing the step of removing the layer 20 (and the step of modifying the main surface 11) and the step of cleaning the inside of the processing vessel 210 in parallel or continuously, it becomes possible to improve their respective productivity. Also, halogen-containing gas, electric power, etc. can be effectively utilized, and it becomes possible to reduce these processing costs.

[0042] In a film-forming apparatus for growing group-III nitrides, originally, cleaning inside the processing chamber is carried out by dry etching using a halogen-containing gas. For this reason, the method for manufacturing a regenerated SiC substrate according to this embodiment can be easily carried out using the film-forming apparatus. By using the film-forming apparatus, it is not necessary to use other processing apparatuses for the regeneration process of the SiC substrate. Further, by carrying out the method for manufacturing a regenerated SiC substrate according to this embodiment using the film-forming apparatus, an effect of cleaning the inside of the processing chamber of the film-forming apparatus can also be obtained.

[0043] <Modification example> The process of removing layer 20 and the process of modifying the main surface 11 may be alternately repeated a plurality of times. Specifically, for example, a period PL which is a set of a period P2 (process of removing layer 20) and a period P3 (process of modifying the main surface 11) in FIG. 3 may be repeatedly carried out a plurality of times.

[0044] Although sufficient effects can be obtained by carrying out only once the process of removing layer 20 and the process of modifying the main surface 11, by repeating these, the effect of cleaning the main surface 11 of the SiC substrate 10 can be further enhanced. Note that, by such repetition, the effect of cleaning the inside of the processing chamber 210 can also be further enhanced.

[0045] <Another modification example> In the above-described embodiment, an aspect of carrying out the regeneration process of one SiC substrate 10 was illustrated. However, in this modification example, an aspect of simultaneously carrying out the regeneration process of a plurality of SiC substrates 10 will be described. In the step of preparing the SiC substrate, a plurality of SiC substrates 10 on which layer 20 is deposited are prepared.

[0046] FIG. 4 is a schematic view showing a susceptor 220 on which a plurality of SiC substrates 10 are placed according to this modified example. The susceptor 220 holds a plurality of SiC substrates 10 so as to revolve and rotate them. While revolving and rotating each SiC substrate 10, a halogen-containing gas is simultaneously supplied to each SiC substrate 10 to etch away the layer 20 of each SiC substrate 10, and after the layer 20 is etched away, a hydrogen-containing gas is simultaneously supplied to each SiC substrate 10 to modify the main surface 11 of each SiC substrate 10.

[0047] According to this modified example, the regeneration process of a plurality of SiC substrates 10 can be efficiently performed. Further, by performing the etching removal of the layer 20 and the modification of the main surface 11 while revolving and rotating a plurality of SiC substrates 10, the variation in the progress of etching and the variation in the progress of the modification of the main surface can be suppressed between each SiC substrate 10 and within the plane of each SiC substrate 10.

[0048] <Other Embodiments> As another embodiment applying the manufacturing method of the regenerated SiC substrate according to the above-described embodiment, a manufacturing method of a laminated structure will be described. The manufacturing method of the laminated structure according to this embodiment includes, in addition to the steps of the manufacturing method of the regenerated SiC substrate described above, a step of growing crystals on the main surface after the modification of the SiC substrate (that is, the main surface of the regenerated SiC substrate). The crystal grown on the main surface of the regenerated SiC substrate is preferably a group III nitride crystal.

[0049] FIG. 5 is a schematic view showing a step of growing (crystals) a new layer 20a made of a group III nitride on the main surface 11 of the regenerated SiC substrate 10a (the main surface 11 after the modification of the SiC substrate 10). Here, a film-forming apparatus is used as a processing apparatus 200 for performing the regeneration process of the SiC substrate 10, and a mode of growing the layer 20a using the same processing apparatus 200 is illustrated.

[0050] For example, the processing device 200 is a MOVPE device, and a layer 20a is grown by MOVPE on the main surface 11 of the regenerated SiC substrate 10a. The process of growing the layer 20a may be continuously performed in the same processing container 210 as the regeneration process of the SiC substrate 10 (that is, the removal process of the layer 20 and the modification process of the main surface 11). In this way, a laminated structure 100a in which the layer 20a is laminated on the main surface 11 of the regenerated SiC substrate 10a is manufactured.

[0051] The Si deficiency region 12 is removed from the main surface 11 of the regenerated SiC substrate 10a, and by growing on the main surface 11, it becomes possible to improve the crystal quality of the layer 20a. As a result, it becomes possible to enhance the performance and reliability of the semiconductor device manufactured using the laminated structure 100a.

[0052] By continuously performing the process of growing the layer 20a in the same processing container 210 as the regeneration process of the SiC substrate 10 (that is, performing it subsequent to the regeneration process), it becomes possible to improve the productivity when manufacturing the laminated structure 100a using the regenerated SiC substrate 10a. In addition, contamination due to exposure of the regenerated SiC substrate 10a to the atmosphere can be avoided, and it becomes possible to enhance the performance and reliability of the semiconductor device manufactured using the laminated structure 100a.

[0053] <Preferred Embodiment of the Present Invention> Hereinafter, preferred embodiments of the present invention will be appended.

[0054] (Appendix 1) (a) A step of preparing a SiC substrate having a group III nitride attached to the main surface; (b) A step of supplying a halogen-containing gas to the SiC substrate to remove the group III nitride from the main surface; (c) A step of supplying a hydrogen-containing gas to the SiC substrate from which the group III nitride has been removed to modify the main surface; A method for manufacturing a regenerated SiC substrate having the above steps.

[0055] (Appendix 2) In (b), an Si-deficient region is formed on the main surface, In (c), the Si-deficient region is removed from the main surface The method for manufacturing a recycled SiC substrate according to Supplementary Note 1.

[0056] (Supplementary Note 3) (b) is performed under conditions such that the Si-deficient region can be formed over the entire area of the main surface The method for manufacturing a recycled SiC substrate according to Supplementary Note 2.

[0057] (Supplementary Note 4) (c) is performed under conditions such that the Si-deficient region can be removed from the entire area of the main surface The method for manufacturing a recycled SiC substrate according to Supplementary Note 2.

[0058] (Supplementary Note 5) (c) is performed under temperature conditions higher than those in (b) The method for manufacturing a recycled SiC substrate according to Supplementary Note 4.

[0059] (Supplementary Note 6) In (b), as the halogen-containing gas, at least any one gas selected from the group consisting of F2 gas, Cl2 gas, Br2 gas, I2 gas, NF3 gas, ClF3 gas, HF gas, HCl gas, HBr gas, and HI is used The method for manufacturing a recycled SiC substrate according to Supplementary Note 1.

[0060] (Supplementary Note 7) In (c), as the hydrogen-containing gas, at least any one gas selected from the group consisting of H2 gas, NH3 gas, N2H2 gas, N2H4 gas, and N3H8 gas is used The method for manufacturing a recycled SiC substrate according to Supplementary Note 1.

[0061] (Supplementary Note 8) The group III nitride contains a substance represented by the composition formula of In x Al y Ga (1-x-y) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, x + y ≦ 1) The method for manufacturing a recycled SiC substrate according to Supplementary Note 1.

[0062] (Supplementary Note 9) Perform the said (b) and the said (c) continuously within the same processing container. The method for manufacturing a recycled SiC substrate according to Supplementary Note 1.

[0063] (Supplementary Note 10) Perform the said (b) and the said (c) in parallel or continuously with the step of supplying a halogen-containing gas into the processing container to clean the inside of the processing container. The method for manufacturing a recycled SiC substrate according to Supplementary Note 1.

[0064] (Supplementary Note 11) Perform the said (b) and the said (c) alternately a plurality of times. The method for manufacturing a recycled SiC substrate according to Supplementary Note 1.

[0065] (Supplementary Note 12) Before performing the said (b), it has the step of annealing the SiC substrate in a reducing atmosphere. The method for manufacturing a recycled SiC substrate according to Supplementary Note 1.

[0066] (Supplementary Note 13) Perform the said (b) and the said (c) in a cold-wall type processing container. The method for manufacturing a recycled SiC substrate according to Supplementary Note 1.

[0067] (Supplementary Note 14) The difference between the thickness of the SiC substrate prepared in the said (a) and the thickness of the SiC substrate after the said (c) is within ±0.0003 mm. The method for manufacturing a recycled SiC substrate according to Supplementary Note 1.

[0068] (Supplementary Note 15) In the said (a), prepare a plurality of SiC substrates with group III nitrides attached to the main surface. In (b) above, a halogen-containing gas is simultaneously supplied to the plurality of SiC substrates to remove group III nitrides from the main surfaces of the respective SiC substrates, in (c) above, a hydrogen-containing gas is simultaneously supplied to each SiC substrate from which the group III nitride has been removed to modify the main surface of each SiC substrate, The method for manufacturing a regenerated SiC substrate according to Supplementary Note 1.

[0069] (Supplementary Note 16) (a) A step of preparing a SiC substrate having a group III nitride attached to the main surface, (b) A step of supplying a halogen-containing gas to the SiC substrate to remove the group III nitride from the main surface, (c) A step of supplying a hydrogen-containing gas to the SiC substrate from which the group III nitride has been removed to modify the main surface, (d) A step of growing crystals on the main surface after modification, A method for manufacturing a laminated structure having the above steps.

[0070] (Supplementary Note 17) Steps (b), (c), and (d) are continuously performed in the same processing container. The method for manufacturing a laminated structure according to Supplementary Note 16.

Explanation of Reference Numerals

[0071] 10... SiC substrate, 10a... regenerated SiC substrate, 11... main surface, 12... Si-deficient region, 20, 20a... layer (made of group III nitride), 100, 100a... laminated structure, 200... processing apparatus, 210... processing container, 220... susceptor, 230... heater, 240... gas supply mechanism, 250... processing gas, 260... deposit

Claims

1. (a) A step of preparing a SiC substrate with a group III nitride attached to the main surface; (b) A step of supplying a halogen-containing gas to the SiC substrate to remove the group III nitride from the main surface; (c) A step of supplying a hydrogen-containing gas to the SiC substrate from which the group III nitride has been removed to modify the main surface; A method for manufacturing a regenerated SiC substrate having the above steps.

2. In the step (b), a Si-deficient region is formed on the main surface; In the step (c), the Si-deficient region is removed from the main surface. The method for manufacturing a regenerated SiC substrate according to Claim 1.

3. The step (b) is performed under conditions that allow the formation of the Si-deficient region over the entire area of the main surface. The method for manufacturing a regenerated SiC substrate according to Claim 2.

4. The step (c) is performed under conditions that allow the removal of the Si-deficient region from the entire area of the main surface. The method for manufacturing a regenerated SiC substrate according to Claim 2.

5. The step (c) is performed under temperature conditions higher than those in the step (b). The method for manufacturing a regenerated SiC substrate according to Claim 4.

6. In the above (b), as the halogen-containing gas, F ２ gas, Cl ２ gas, Br ２ gas, I ２ gas, NF ３ gas, ClF ３ gas, HF gas, HCl gas, HBr gas, and at least any one gas selected from the group consisting of HI is used The method for manufacturing a regenerated SiC substrate according to Claim 1.

7. In the above (c), as the hydrogen-containing gas, H ２ gas, NH ３ gas, N ２ H ２ gas, N ２ H ４ gas, and at least any one gas selected from the group consisting of N ３ H ８ gas is used The method for manufacturing a regenerated SiC substrate according to Claim 1.

8. The group III nitride includes In ｘ Al ｙ Ga （１－ｘ－ｙ） a substance represented by a composition formula of N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, x + y ≦ 1). The method for manufacturing a regenerated SiC substrate according to Claim 1.

9. The steps (b) and (c) are continuously performed in the same processing container. The method for manufacturing a regenerated SiC substrate according to Claim 1.

10. The steps (b) and (c), and a step of supplying a halogen-containing gas into the processing container to clean the inside of the processing container are performed in parallel or continuously. The method for manufacturing a regenerated SiC substrate according to Claim 1.

11. The steps (b) and (c) are alternately performed a plurality of times. The method for manufacturing a regenerated SiC substrate according to Claim 1.

12. Before performing the step (b), the method includes a step of annealing the SiC substrate in a reducing atmosphere. The method for manufacturing a regenerated SiC substrate according to Claim 1.

13. The steps (b) and (c) are performed in a cold-wall type processing container. The method for manufacturing a regenerated SiC substrate according to Claim 1.

14. The difference between the thickness of the SiC substrate prepared in the step (a) and the thickness of the SiC substrate after the step (c) is within ±0.0003 mm. The method for manufacturing a regenerated SiC substrate according to Claim 1.

15. In the step (a), a plurality of SiC substrates with a group III nitride attached to the main surface are prepared. In the step (b), a halogen-containing gas is supplied to the plurality of SiC substrates simultaneously to remove the group-III nitride from the main surfaces of the respective SiC substrates. In the step (c), a hydrogen-containing gas is supplied to the respective SiC substrates from which the group-III nitride has been removed, to modify the main surfaces of the respective SiC substrates. The method for manufacturing a regenerated SiC substrate according to claim 1.

16. (a) A step of preparing a SiC substrate having a group-III nitride attached to a main surface; (b) A step of supplying a halogen-containing gas to the SiC substrate to remove the group-III nitride from the main surface; (c) A step of supplying a hydrogen-containing gas to the SiC substrate from which the group-III nitride has been removed, to modify the main surface; (d) A step of growing crystals on the modified main surface; A method for manufacturing a laminated structure having the above steps.

17. The steps (b), (c) and (d) are continuously carried out in the same processing vessel. The method for manufacturing a laminated structure according to claim 16.

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