Method for manufacturing si c substrate

Abstract

The present invention provides a novel technique for manufacturing a SiC substrate that can reduce material loss when removing a strain layer. The present invention is a method for manufacturing a SiC substrate (30) that includes a strain layer thinning step (S1) that thins a strain layer (12) of a SiC substrate body (10) by moving the strain layer (12) to the surface side. In this way, by including the strain layer thinning step (S1) that moves (concentrates) the strain layer (12) to the surface side, material loss (L) when removing the strain layer (12) can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for manufacturing a SiC substrate. BACKGROUND

[0002] A SiC (silicon carbide) substrate is formed by slicing a crystal ingot of a single crystal SiC. At the surface of the SiC substrate after slicing, there is a surface layer (hereinafter referred to as a processing metamorphic layer) having a deformation or a scratch of a crystal introduced at the time of slicing or the like. In order not to reduce the yield of a product in a device manufacturing step, it is necessary to remove this processing metamorphic layer.

[0003] Conventionally, in order to obtain a SiC substrate that is free of the processing metamorphic layer and that can undergo epitaxial growth for manufacturing a SiC device, mechanical processing is performed. As this mechanical processing, generally, the following stages are passed through: a rough grinding step using abrasive grains such as diamond, a fine grinding step using abrasive grains having a smaller particle diameter than the abrasive grains used in the rough grinding step, and a chemical mechanical polishing (CMP) step in which a mechanical action of a polishing pad and a chemical action of a slurry are combined to perform polishing (for example, refer to Patent Literature 1).

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2015-5702 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In addition, the processing metamorphic layer is considered to have a crack layer having a large number of cracks (scratches) and a strain layer in which a crystal lattice is strained. The strain layer is introduced to a position deeper than the crack layer in the SiC substrate. Therefore, in order to remove the strain layer, it is necessary to remove single crystal SiC of several tens of μm to several hundreds of μm. Thus, there is a problem that a large amount of material loss occurs.

[0009] In particular, in the case where removal of the strain layer is performed by CMP, it takes several hours to remove single crystal SiC of several μm to several tens of μm, and there are problems of high cost required for the CMP and long processing time.

[0010] In view of the above problems, it is an object of the present application to provide a new technology for manufacturing a SiC substrate that can reduce the amount of material loss at the time of removing a strain layer.

[0011] MEANS FOR SOLVING THE PROBLEMS

[0012] The present application is a method for manufacturing a SiC substrate, which includes a strain layer thinning step of thinning a strain layer of a SiC substrate body by moving the strain layer to the surface side.

[0013] Thus, by including a step of moving (concentrating) the strain layer to the surface side, the amount of material loss of the SiC substrate body in a strain layer removal step of removing the strain layer, which is performed subsequently, can be reduced. In addition, the processing cost or processing time in the strain layer removal step can be reduced.

[0014] In a preferred mode of the present application, the strain layer removal step of removing the strain layer includes a step of removing at least a portion of the strain layer on the surface side of a reference depth,

[0015] The strain layer thinning step is a step of moving the strain layer to the surface side of a reference depth, in the case where the depth of the strain layer before the strain layer thinning step is set as the reference depth,

[0016] The strain layer removal step is a step of removing at least a portion of the strain layer on the surface side of the reference depth.

[0017] Thus, by moving the strain layer to the surface side of the reference depth after conventional removal and performing removal, the amount of material loss of the SiC substrate body can be reduced.

[0018] In a preferred mode of the present application, the strain layer removal step is chemical mechanical polishing.

[0019] Thus, by performing chemical mechanical polishing after thinning the strain layer of the SiC substrate body by moving the strain layer to the surface side, an epitaxial-ready surface can be formed while reducing the amount of material loss and cost.

[0020] In a preferred mode of the present application, the strain layer removal step is a thermal etching method.

[0021] Thus, by employing a thermal etching method in the strain layer removal step, the movement of the strain layer and the removal of the strain layer can be performed simultaneously. That is, the strain layer thinning step and the strain layer removal step can be executed simultaneously.

[0022] In a preferred mode of the present application, a slicing step of slicing a crystal ingot to obtain a SiC substrate body is further included, and the slicing step is a step of obtaining a SiC substrate body having a thickness of 100 μm or less added to the thickness of the SiC substrate body after the strain layer removal step.

[0023] Further, the slicing step is a step of obtaining a SiC substrate body having a thickness of 50 μm or less added to the thickness of the SiC substrate body after the strain layer removal step.

[0024] By slicing the SiC substrate body to such a thickness, the number of SiC substrate bodies that can be obtained from one ingot can be increased, and the unit price of each piece can be reduced.

[0025] In a preferred embodiment of the present application, an etching step of etching the surface of the SiC substrate body is further included, and the etching step is wet etching.

[0026] In this way, by wet etching the SiC substrate body, the impurities adhered in the slicing step can be removed while planarizing the surface.

[0027] In a preferred embodiment of the present application, in the etching step, as an etching solution, one or two or more selected from the group consisting of a potassium hydroxide molten solution, a solution containing hydrofluoric acid, a potassium permanganate solution, and tetramethylammonium hydroxide are included.

[0028] In a preferred embodiment of the present application, a slicing step of slicing an ingot to obtain a SiC substrate body is included, and the slicing step, the etching step, and the strain layer thinning step are sequentially included.

[0029] In a preferred embodiment of the present application, the strain layer thinning step is a step of heating the SiC substrate body in an environment containing Si elements.

[0030] In a preferred embodiment of the present application, the strain layer thinning step is a step of heating the SiC substrate body in a quasi-closed space including a Si element supply source and a C element supply source.

[0031] In a preferred embodiment of the present application, the strain layer thinning step is a step of heating the SiC substrate body in a main container made of a SiC material.

[0032] In a preferred embodiment of the present application, the strain layer thinning step is a step of relatively arranging the SiC substrate body and a SiC material and heating them in a manner to form a temperature gradient between the SiC substrate body and the SiC material.

[0033] In a preferred embodiment of the present application, the strain layer thinning step is a step of heating the SiC substrate body in a Si vapor pressure environment.

[0034] In a preferred embodiment of the present application, the strain layer thinning step is a spinodal solvent epitaxy method.

[0035] In a preferred embodiment of the present application, the heating temperature of the strain layer thinning step is 1400°C or higher and 1600°C or lower.

[0036] Effects of the Invention

[0037] According to the disclosed technology, a new technology for manufacturing a SiC substrate capable of reducing the amount of material loss when removing a strain layer can be provided.

[0038] Other technical problems to be solved, features and advantages will become apparent by reading the following detailed description in connection with the accompanying drawings and claims. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is a schematic diagram of the manufacturing steps of a SiC substrate according to the present application and a conventional method.

[0040] Figure 2 is a schematic diagram of the manufacturing steps of a SiC substrate according to the embodiment.

[0041] Figure 3 is a schematic diagram showing an outline of the strain layer thinning step according to the embodiment.

[0042] Figure 4 is a schematic diagram showing an outline of the strain layer thinning step according to the embodiment.

[0043] Figure 5 is a schematic diagram showing an outline of the strain layer thinning step according to the embodiment.

[0044] Figure 6 is a schematic diagram of a manufacturing apparatus of a SiC substrate according to the embodiment.

[0045] Figure 7 is a schematic diagram of a manufacturing apparatus of a SiC substrate according to Embodiment 1.

[0046] Figure 8 is a schematic diagram of a SiC substrate according to Embodiment 1. DETAILED DESCRIPTION

[0047] Hereinafter, a preferred embodiment of the present application will be described in detail with reference to the accompanying drawings. The technical scope of the present application is not limited to the embodiment shown in the drawings, but various modifications can be made within the scope of the claims.

[0048] Manufacturing method of SiC substrate

[0049] Figure 1 and Figure 2 is a schematic diagram comparing the manufacturing method of a SiC substrate according to the embodiment of the present application with the manufacturing method of a SiC substrate according to a conventional method.

[0050] Figure 1 Embodiments are shown in which the strain layer 12 is thinned and removed for a SiC substrate body 10 having a strain layer 12. On the other hand, Figure 2An embodiment is shown in which a SiC substrate 30 with substrate thickness D is obtained from an ingot I with thickness D0.

[0051] like Figure 1 (a) to Figure 1 (c) and Figure 2 As shown in (a), the present invention is a method for manufacturing a SiC substrate 30, which includes: a strain layer thinning step S1, wherein the strain layer 12 of the SiC substrate body 10 is thinned by moving (concentrating) the strain layer 12 to the surface side.

[0052] Specifically, the strain layer thinning step S1 is a step of moving the strain layer 12 after the strain layer thinning step closer to the surface side than the reference depth 20, while setting the depth of the strain layer 12 before the strain layer thinning step as the reference depth 20.

[0053] Furthermore, the present invention provides a method for manufacturing a SiC substrate 30, comprising: a strain layer removal step S2, which removes the strain layer 12 that has been moved by the strain layer thinning step S1. This strain layer removal step S2 removes at least a portion of the strain layer closer to the surface side than a reference depth 20.

[0054] Figure 1 (a) shows an embodiment in which the strain layer 12 is moved to the surface side while maintaining the substrate thickness of the SiC substrate body 10. Figure 1 (b) shows an embodiment in which the strain layer 12 is moved to the surface side while the SiC substrate 10 is crystal grown. Figure 1 (c) shows an embodiment in which the strain layer 12 is moved to the surface side while the SiC substrate 10 is being etched.

[0055] On the other hand, such as Figure 1 As shown in (d), the conventional method includes a strain layer removal step S2 to remove all strain layers 12. That is, in order to remove the strain layer 12, the SiC single crystal needs to be removed at least to a reference depth 20. Thus, when all the introduced strain layer 12 is removed, a large amount of material loss L occurs.

[0056] That is, according to the present invention, the method includes a strain layer thinning step S1, in which the strain layer 12 is thinned by moving (concentrating) the strain layer 12 of the SiC substrate 10 to the surface side before (or while removing the strain layer 12). Thus, compared with conventional methods, the amount of material loss L of the SiC substrate 10 can be reduced.

[0057] also, Figure 2The embodiment of the present invention shown in (a) is a method for manufacturing a SiC substrate 30, which includes: a slicing step S3, slicing an ingot I to obtain a SiC substrate body 10; an etching step S4, etching the surface of the SiC substrate body 10; a strain layer thinning step S1, thinning the strain layer 12 by moving (concentrating) the strain layer 12 of the SiC substrate body 10 to the surface side; and a strain layer removal step S2, removing the moved strain layer 12.

[0058] According to the present invention, the amount of material loss L can be reduced through the strain layer thinning step S1. Therefore, the SiC substrate 10 can be sliced ​​with a substrate thickness D1 thinner than conventional methods. Figure 2 In (a), it is shown that four SiC substrates 30 with a substrate thickness of D are obtained from an ingot I with a thickness of D0.

[0059] On the other hand, such as Figure 2 As shown in (b), the conventional method includes a strain layer removal step S2, which removes all the strain layer 12 introduced into the SiC substrate 10. Therefore, in order to manufacture the SiC substrate 30 with a substrate thickness D manufactured in this invention, it is necessary to slice it with a substrate thickness D2 that is thicker than the substrate thickness D1. Figure 2 In (b), the case of obtaining three SiC substrates 30 with a substrate thickness of D from an ingot I with a thickness of D0 is shown.

[0060] Thus, when obtaining SiC substrates 30 with the same substrate thickness D starting from ingot I with thickness D0, the number of SiC substrates 30 obtained in the present invention including strain layer thinning step S1 and the conventional method excluding strain layer thinning step S1 are different.

[0061] That is, according to this embodiment, there is a strain layer thinning step S1, which involves moving (concentrating) the strain layer 12 of the SiC substrate body 10 to the surface side to thin the strain layer 12. This can increase the number of SiC substrates 30 obtained from one ingot and reduce the unit price of each substrate.

[0062] The following is based on Figure 2 The embodiment shown describes the slicing step S3, the etching step S4, the strain layer thinning step S1, and the strain layer removal step S2 in detail in sequence.

[0063] <Slicing steps>

[0064] The slicing step S3 is a step of cutting the SiC substrate body 10 from the ingot I. As a slicing method of the slicing step S3, the following can be exemplified: a multi-wire saw cutting that cuts the ingot I at predetermined intervals by reciprocating a plurality of wires; an electric discharge machining method that cuts by intermittently generating plasma discharge; and a cutting using laser that forms a layer that becomes a base point of cutting by irradiating / converging laser in the ingot I.

[0065] The substrate thickness of the SiC substrate body 10 is determined in accordance with the intervals at which the cutting is performed in the slicing step S3. The substrate thickness is set to a thickness after a single-crystal SiC (material loss L) removed in a future step is taken into account. In this way, since the slicing thickness from the ingot I is set taking into account the amount of material loss L after all the processing steps, the specific numerical value is described after all the steps are described.

[0066] <etching step>

[0067] The etching step S4 is a step of etching the surface of the SiC substrate body 10 after the slicing step S3. As an etching method of the etching step S4, a thermal etching method such as SiVE method or hydrogen etching method, a wet etching method using a potassium hydroxide molten solution, a drug solution containing hydrofluoric acid, a potassium permanganate-based drug solution, a drug solution containing tetramethylammonium hydroxide, and the like can be exemplified. In addition, in general, any drug solution used in wet etching can be adopted.

[0068] Among them, it is preferable that the etching step S4 etches the surface of the SiC substrate body 10 using a potassium hydroxide molten solution. By etching the surface of the SiC substrate body 10 using so-called KOH etching, it is possible to simultaneously remove impurities adhered in the slicing step S3 while planarizing the surface.

[0069] Specifically, the SiC substrate body 10 after the slicing step S3 can be subjected to the etching step S4 using a potassium hydroxide molten solution, followed by the strain layer thinning step S1 and the strain layer removing step S2.

[0070] <strain layer thinning step>

[0071] The strain layer thinning step S1 is a step of heating the SiC substrate body 10 to at least 1400°C or higher in an environment containing Si element. By heating the SiC substrate body 10 in such an environment, it is possible to move / concentrate the strain layer 12 to the surface side of the SiC substrate body 10 without carbonizing the surface of the SiC substrate body 10.

[0072] Examples of methods that can be used in the strain layer thinning step S1 include: metastable solvent epitaxy (MSE) method, which grows single-crystal SiC by heating a sandwich structure of polycrystalline SiC and single-crystal SiC configured via single-crystal Si; and Si-vapor etch (SiVE) method, which etches single-crystal SiC by heating under Si vapor pressure.

[0073] That is, it is desirable that the heat treatment environment of the SiC substrate 10 in the strain layer thinning step S1 is a gas phase environment containing Si or a liquid phase environment containing Si.

[0074] In addition to the SiVE or MSE methods mentioned above, the following methods can also be cited.

[0075] According to an embodiment of the present invention, the strain layer thinning step S1 is a step of heating the SiC substrate 10 in a quasi-enclosed space including a Si element supply source and a C element supply source.

[0076] Specifically, such as Figure 3 As shown, a SiC substrate 10 is disposed within a main container 50 that exposes the SiC material 40 (a Si element supply source and a C element supply source). By heating the main container 50, a gaseous environment containing Si elements can be formed within the container.

[0077] Additionally, the term "quasi-closed space" in this specification refers to a space capable of being evacuated within the container, but capable of containing at least a portion of the vapor generated within the container. This quasi-closed space may be formed within the main container 50 described later or within the high-melting-point container 70.

[0078] The SiC substrate 10 can be exemplified as a substrate obtained by processing single-crystal SiC into a plate shape. Specifically, it can be exemplified as a SiC wafer or the like, which is obtained by slicing a SiC ingot manufactured using a sublimation method into a disk shape. Furthermore, any polymorph can be used as the crystal polymorph of single-crystal SiC.

[0079] Typically, the SiC substrate 10 after machining (e.g., slicing, grinding / polishing) or laser processing has: a strained layer 12 inducing lattice strain due to processing damage, and a bulk layer 11 without introducing such processing damage (see reference). Figure 1 To manufacture a high-quality SiC substrate 30, it is preferable to remove the strain layer 12 and expose the bulk layer 11, which has not been subjected to processing damage.

[0080] In addition, generally, a crack layer having a large number of cracks (scratches) is introduced in addition to the strain layer 12 due to processing damage, but is omitted since it is introduced to a shallower position than the strain layer 12. This crack layer or the strain layer 12 is collectively referred to as a processing modification layer.

[0081] The presence or absence or depth of the strain layer 12 can be confirmed by an SEM-EBSD method, a TEM, a μXRD, a Raman spectroscopy, or the like.

[0082] The SiC material 40 includes a SiC substrate or a SiC container (the main container 50 itself). That is, a manner in which a SiC substrate that is to become the SiC material 40 is disposed in a container separately from the SiC substrate body 10 can be exemplified (refer to Figure 4 and Figure 5 ).

[0083] Further, a manner in which at least a portion of a container that houses the SiC substrate body 10 is formed of the SiC material 40 can be exemplified (refer to Figure 7 ). In this case, either the entire container can be formed of the SiC material 40 or a portion opposite the SiC substrate body 10 can be formed of the SiC material 40.

[0084] In addition, in a case where the SiC material 40 employs a single crystal SiC, any polymorphic form can be employed.

[0085] It is desirable that a vapor pressure environment that becomes a mixed system of a gas phase species containing a Si element and a gas phase species containing a C element be present in the quasi-closed space after heating. As the gas phase species containing a Si element, Si, Si2, Si3, Si2C, SiC2, SiC can be exemplified. Further, as the gas phase species containing a C element, Si2C, SiC2, SiC, C can be exemplified. That is, it is preferable that a SiC-based gas be present in a state in the quasi-closed space.

[0086] The heating temperature in the strain layer thinning step S1 is preferably set in a range of 1400 to 2300°C. Further, it is more preferable to be set in a range of 1400 to 1600°C.

[0087] The heating time in the strain layer thinning step S1 can be set to any time that enables a desired depth of the strain layer 12 to be achieved.

[0088] By heating the SiC substrate body 10 in such an environment, the strain layer 12 can be moved (concentrated) to the surface side, and the strain layer 12 can be thinned (refer to Figure 3 ).

[0089] Further, according to the strain layer thinning step S1 of the present embodiment, by relatively arranging the SiC substrate body 10 and the SiC material 40 and heating in a manner to form a temperature gradient between the SiC substrate body 10 and the SiC material 40, the strain layer 12 can be thinned while the SiC substrate body 10 is subjected to crystal growth or etching.

[0090] Hereinafter, the strain layer thinning step S1 is explained in detail, divided into a case with etching and a case with crystal growth.

[0091] [Strain layer thinning step S1 with crystal growth]

[0092] Figure 1 (b) and Figure 4 is an explanatory diagram showing an outline of the strain layer thinning step S1 with crystal growth. As shown in Figure 4 , by relatively arranging the SiC substrate body 10 and the SiC material 40 and heating in a manner to form a temperature gradient between them, it is possible to transport the raw material (Si element and C element) from the SiC material 40 to the SiC substrate body 10 and grow a single crystal SiC.

[0093] In this strain layer thinning step S1, the SiC substrate body 10 is arranged in the quasi-enclosed space exposed by the SiC material 40, and heated in a temperature range of 1400°C or higher and 2300°C or lower, thereby continuously performing the reactions of 1) to 5) below, and as a result, it is considered that crystal growth is performed (refer to (b) of Figure 4 ).

[0094] 1) Poly-SiC (s) → Si (v) + C (s)

[0095] 2) 2C (s) + Si (v) → SiC2 (v)

[0096] 3) C (s) + 2Si (v) → Si2C (v)

[0097] 4) Si (v) + SiC2 (v) → 2SiC (s)

[0098] 5) Si2C (v) → Si (v) + SiC (s)

[0099] Explanation of 1): By heating the SiC material (Poly-SiC (s)), Si atoms (Si (v)) are detached from the SiC by thermal decomposition.

[0100] Explanation of 2) and 3): C atoms (C (s)) remaining due to the detachment of Si atoms (Si (v)) react with Si vapor (Si (v)) in the quasi-enclosed space. As a result, the C atoms (C (s)) become Si2C or SiC2 or the like and sublimate in the quasi-enclosed space.

[0101] 4) and 5) are described: The sublimated Si2C or SiC2 or the like reaches / diffuses to the platform of the SiC substrate body 10 and to the step due to the temperature gradient (or the chemical potential difference), and thereby the polymorph of the SiC substrate body 10 of the base is continued and grown (step-flow growth).

[0102] Thus, the strain layer thinning step S1 accompanying the crystal growth includes: a Si atom sublimation step of thermally sublimating Si atoms from the surface of the SiC material 40; a C atom sublimation step of sublimating C atoms remaining at the surface of the SiC material 40 by reacting with the Si vapor in the quasi-enclosed space; a raw material delivery step of delivering the raw material to the surface of the SiC substrate body 10 with the temperature gradient or the chemical potential difference as a driving force; and a step-flow growth step of growing the raw material that has reached the step of the SiC substrate body 10.

[0103] That is, the strain layer thinning step S1 accompanying the crystal growth is a step of relatively arranging the SiC substrate body 10 and the SiC material 40 and heating them in a manner that the SiC substrate body 10 is the low-temperature side and the SiC material 40 is the high-temperature side. Thereby, a crystal growth space X is formed between the SiC substrate body 10 and the SiC material 40, the SiC substrate body 10 can be caused to grow crystals with the temperature gradient as a driving force, and the strain layer 12 can be moved to the surface side of the SiC substrate body 10.

[0104] [Strain layer thinning step S1 accompanying etching]

[0105] Figure 1 (c) and Figure 5 is an explanatory view showing an outline of the strain layer thinning step S1 accompanying the etching. As shown in Figure 5 by relatively arranging the SiC substrate body 10 and the SiC material 40 and setting a temperature gradient therebetween and heating them, the raw material (Si element and C element) can be delivered from the SiC substrate body 10 to the SiC material 40 and the SiC substrate body 10 can be etched.

[0106] In this strain layer thinning step S1, the SiC substrate body 10 is arranged in the quasi-enclosed space exposed by the SiC material 40, and heating is performed in a temperature range of 1400°C or higher and 2300°C or lower, whereby the reactions of the following 1) to 5) are continuously performed, and as a result, it is considered that etching is performed (refer to Figure 5 (b) in

[0107] 1) SiC (s) → Si (v) + C (s)

[0108] 2) 2C (s) + Si (v) → SiC2 (v)

[0109] 3) C(s) + 2Si(v) → Si2C(v)

[0110] 4) Si(v) + SiC2(v) → 2SiC(s)

[0111] 5) Si2C(v) → Si(v) + SiC(s)

[0112] Explanation of 1): Since the SiC substrate body 10 (SiC(s)) is heated, Si atoms (Si(v)) are desorbed from the surface of the SiC substrate body 10 by thermal decomposition (Si atom sublimation step).

[0113] Explanation of 2) and 3): C (C(s)) remaining at the surface of the SiC substrate body 10 due to desorption of Si atoms (Si(v)) reacts with Si vapor (Si(v)) in the quasi-enclosed space. As a result, C (C(s)) becomes Si2C or SiC2 or the like and sublimates from the surface of the SiC substrate body 10 (C atom sublimation step).

[0114] Explanation of 4) and 5): The sublimated Si2C or SiC2 or the like reaches the SiC material 40 in the quasi-enclosed space due to the temperature gradient, and crystal growth is performed.

[0115] Thus, the strain layer thinning step S1 with etching includes a Si atom sublimation step of thermally sublimating Si atoms from the surface of the SiC substrate body 10, and a C atom sublimation step of sublimating C atoms remaining at the surface of the SiC substrate body 10 from the surface of the SiC substrate body 10 by reacting the C atoms with Si vapor in the quasi-enclosed space.

[0116] That is, the strain layer thinning step S1 with etching is a step of relatively arranging the SiC substrate body 10 and the SiC material 40 and heating them in a manner that the SiC substrate body 10 is the high-temperature side and the SiC material 40 is the low-temperature side.

[0117] Thus, the etching space Y is formed between the SiC substrate body 10 and the SiC material 40, the SiC substrate body 10 can be etched with the temperature gradient as a driving force, and the strain layer 12 can be moved to the surface side of the SiC substrate body 10.

[0118] <Strain layer removal step>

[0119] The strain layer removal step S2 is a step of removing the strain layer 12 that is thinned by the strain layer thinning step S1. Specifically, it is a step of removing the strain layer 12 that is moved more to the surface side than a reference depth 20, which is the depth of the strain layer 12 before the strain layer thinning step S1, that is, a step of removing at least a part that is closer to the surface side than the reference depth 20. Figure 1 (a) to Figure 1(c) in (b).

[0120] As a method used in the strain layer removal step S2, a CMP method, a SiVE method, a hydrogen etching method, and the etching method described in the "strain layer thinning step S1 with etching" above can be exemplified.

[0121] In addition, the strain layer removal step S2 in the conventional method generally goes through the following stages: a rough grinding step using abrasive grains such as diamond, a fine grinding step using abrasive grains having a smaller particle diameter than the abrasive grains used in the rough grinding step, and a CMP step in which the mechanical action of a polishing pad and the chemical action of slurry are combined to perform polishing. In this conventional method, generally, the entire strain layer 12 introduced into the SiC substrate body 10 is removed (refer to FIG. 2). Figure 1 (d) in (c).

[0122] In the strain layer removal step S2 according to the present application, the strain layer 12 after the strain layer thinning step S1 is removed. Therefore, the strain layer 12 can be removed in a smaller removal amount than the conventional introduced strain layer depth (reference depth 20). Thus, compared to the conventional method, the removal amount of the SiC substrate body 10 in the strain layer removal step S2 of the present application can be reduced.

[0123] The SiC substrate manufacturing method according to the present application includes a strain layer thinning step S1 in which the strain layer 12 of the SiC substrate body 10 is thinned by moving the strain layer 12 to the surface side. Thus, the material loss L amount in the strain layer removal step S2 can be reduced. In addition, the cost or processing time in the strain layer removal step S2 can be reduced.

[0124] For example, consider the case where the depth of the strain layer 12 of the SiC substrate body 10 before the strain layer thinning step S1 (reference depth 20) is 5 μm, and the depth of the strain layer 12 is changed to 1 μm by the strain layer thinning step S1. At this time, in the strain layer removal step S2, 1 μm amount of the SiC substrate body 10 is removed. That is, in the conventional method, 5 μm amount of the SiC substrate body 10 needs to be removed, but by including the strain layer thinning step S1, 4 μm amount of material loss L can be reduced. In addition, the consumables (grinding stones, blades, abrasive grains, etc.) or processing time taken for processing can be reduced. Therefore, the cost in the strain layer removal step S2 can be greatly reduced.

[0125] The SiC substrate manufacturing method according to the present embodiment, by employing chemical mechanical polishing (CMP) in the strain layer removal step S2, can manufacture a SiC substrate 30 having an epitaxial-ready surface while reducing the material loss L / cost / processing time. The present application, by thinning the strain layer 12, can reduce the burden of the fine processing, i.e., CMP, of the conventional method.

[0126] According to the method for manufacturing a SiC substrate of the present embodiment, by employing the strain layer thinning step S1 along with the crystal growth, it is possible to adjust the substrate thickness to a desired thickness.

[0127] According to the method for manufacturing a SiC substrate of the present embodiment, by employing the strain layer thinning step S1 along with the etching, it is possible to simultaneously perform the strain layer thinning step S1 and the strain layer removing step S2. Thereby, it is possible to reduce the introduction cost of steps and apparatuses and outsourcing cost, and it is possible to reduce the cost.

[0128] According to the method for manufacturing a SiC substrate of the present embodiment, the heating temperature of the strain layer thinning step S1 is 1400°C or higher and 1600°C or lower. By performing the heating in such a temperature range, it is possible to reduce the burden on the apparatus. Further, the lower the temperature of the heat treatment apparatus, the easier it is to introduce.

[0129] [Slice thickness in the slicing step]

[0130] Table 1 summarizes an example of a case where a SiC substrate 30 having a substrate thickness of 350 μm is manufactured in the respective methods for manufacturing a SiC substrate of the present embodiment and the conventional method.

[0131] [Table 1]

[0132]

[0133]

[0134]

[0135] As shown in Table 1, in the conventional method, a material loss L of 100 μm in total is generated. In particular, in the conventional method, in order to reliably remove the strain layer 12 introduced in each step, 100 μm or more is generally removed per one SiC substrate body 10.

[0136] On the other hand, as shown in Table 1, the amount of material loss L in the method for manufacturing a SiC substrate of the present embodiment is 50 μm. As described above, according to the present embodiment, it is possible to greatly reduce the amount of material loss L in the manufacturing of a SiC substrate.

[0137] Further, the substrate thickness D1 of the SiC substrate body 10 cut from the ingot I in the slicing step S3 is set with the amount of material loss L as an index. That is, the thickness obtained by adding the amount of material loss L to the substrate thickness D of the SiC substrate 30 finally intended to be obtained (the thickness of the SiC substrate 30 at the end of surface processing) is set as the substrate thickness D1 at the time of slicing.

[0138] As described above, the thickness Dl of the substrate at the time of slicing is determined by adding the amount of material loss L to the thickness of the SiC substrate 30 after the surface processing. The "surface processing" herein refers to processing that reduces the thickness of the SiC substrate body 10, such as the etching step S4, the strain layer removal step S2.

[0139] That is, the thickness Dl of the substrate at the time of slicing is set by adding the amount of material loss L to the thickness of the SiC substrate 30 at the time point at which the thickness has reached a point at which it is no longer reduced by the subsequent steps.

[0140] Therefore, it is preferable that a value obtained by adding a thickness of 37 μm or more, more preferably 40 μm or more, as a lower limit, to the substrate thickness D of the SiC substrate 30 be set as the thickness Dl of the substrate at the time of slicing.

[0141] Further, it is preferable that a value obtained by adding a thickness of 100 μm or less, more preferably 90 μm or less, further preferably 80 μm or less, further preferably 70 μm or less, further preferably 60 μm or less, further preferably 50 μm or less, as an upper limit, to the substrate thickness D of the SiC substrate 30 be set as the thickness Dl of the substrate at the time of slicing. Thereby, more SiC substrates 30 can be manufactured from one ingot I.

[0142] Further, as described above, in the conventional method, 100 μm or more is generally removed per one SiC substrate 30. Therefore, it is preferable that a value obtained by adding a thickness of 100 μm or less, more preferably less than 100 μm, as an upper limit, to the substrate thickness D of the SiC substrate 30 be set as the thickness Dl of the substrate at the time of slicing. Thereby, compared to when the conventional method that is generally performed is used, more SiC substrates 30 can be manufactured.

[0143] In addition, the substrate thickness D of the SiC substrate 30 that has undergone the slicing step S3 to the strain layer removal step S2 can be exemplified as: typically 100 to 600 μm, more typically 150 to 550 μm, further typically 200 to 500 μm, further typically 250 to 450 μm, further typically 300 to 400 μm.

[0144] That is, it is preferable that the thickness Dl of the substrate at the time of slicing be set by adding the amount of material loss L according to the method of manufacturing a SiC substrate of the present application to the substrate thickness D of these typical SiC substrates 30.

[0145] Specifically, according to the SiC substrate manufacturing method of the present invention, when it is desired to obtain a SiC substrate 30 with a substrate thickness D of 350 μm as the final product, it is preferable that the substrate thickness D1 obtained in the slicing step S3 is a SiC substrate 30 with a lower limit of 387 μm or more, more preferably 390 μm or more, and even more preferably 400 μm or more.

[0146] Furthermore, in this case, it is preferable that the substrate thickness D1 obtained in the slicing step S3 is a SiC substrate 30 with an upper limit of 450 μm or less, more preferably 440 μm or less, even more preferably 430 μm or less, even more preferably 420 μm or less, even more preferably 410 μm or less, and even more preferably 400 μm or less.

[0147] Fabrication Apparatus for SiC Substrates

[0148] Hereinafter, a detailed description will be given of the manufacturing apparatus for implementing the manufacturing method of the SiC substrate according to the present invention. Furthermore, in this embodiment, structural elements that are substantially the same as those shown in the aforementioned manufacturing method will be labeled with the same reference numerals, and their descriptions will be simplified.

[0149] like Figure 6 As shown, the SiC substrate manufacturing apparatus according to this embodiment includes: a main container 50 capable of housing the SiC substrate 10; and a heating furnace 60 capable of heating to form a temperature gradient between the SiC substrate 10 and the SiC material 40.

[0150] (Main Container)

[0151] The main container 50 is a fitted container comprising an upper container 51 and a lower container 52 that can fit together. A small gap 53 is formed at the fitting part of the upper container 51 and the lower container 52, and is configured to allow air to be vented (vacuumed) from the main container 50 through the gap 53.

[0152] According to this embodiment, the upper container 51 and the lower container 52 are made of polycrystalline SiC. Therefore, the main container 50 itself may also be made of SiC material 40. Alternatively, only the portion of the main container 50 opposite to the SiC substrate 10 may be made of SiC material 40. In this case, the portions other than SiC material 40 may be made of a high-melting-point material (the same material as the high-melting-point container 70 described later).

[0153] In addition, such as Figure 3 to Figure 5As shown, a structure in which the substrate-like SiC material 40 is housed alone can also be employed. In this case, a spacer (substrate holding tool 54 or the like) can also be arranged between the substrate-like SiC material 40 and the SiC substrate body 10 to form a crystal growth space X or an etching space Y. It is desirable that the substrate holding tool 54 be composed of the same high-melting-point material as the high-melting-point container 70.

[0154] That is, the main container 50 is configured to generate an atmosphere containing Si and C elements in the internal space when heated in a state in which the SiC substrate body 10 is housed. In the present embodiment, by heating the SiC material 40 composed of polycrystalline SiC, an atmosphere containing Si and C elements is formed in the internal space.

[0155] Further, it is desirable that the space in the main container 50 after heating become a vapor pressure environment of a mixed system of a gas phase species containing Si elements and a gas phase species containing C elements. As the gas phase species containing Si elements, Si, Si2, Si3, Si2C, SiC2, SiC can be exemplified. Further, as the gas phase species containing C elements, Si2C, SiC2, SiC, C can be exemplified. That is, it is preferable to become a state in which a SiC-based gas exists in the quasi-closed space.

[0156] The crystal growth space X or the etching space Y is a space in which the temperature gradient provided between the SiC substrate body 10 and the SiC material 40 is used as a driving force to transport the raw material from the SiC substrate body 10 to the SiC material 40, and is a space in which the raw material is transported from the SiC material 40 to the SiC substrate body 10.

[0157] For example, a case is considered in which the SiC substrate body 10 is arranged such that, when the temperature of the surface of the SiC substrate body 10 and the temperature of the SiC material 40 opposite the surface are compared, the temperature on the SiC substrate body 10 side is low, and the temperature of the SiC material 40 is high (refer to FIG. 2). Figure 4 In this way, in a case in which the SiC substrate body 10 and the SiC material 40 are arranged opposite each other and heated such that the SiC substrate body 10 is the low-temperature side and the SiC material 40 is the high-temperature side, the raw material is transported from the SiC material 40 to the SiC substrate body 10, and single-crystal SiC grows on the SiC substrate body 10. That is, a crystal growth space X is formed between the SiC material 40 and the SiC substrate body 10.

[0158] On the other hand, a case is considered in which the SiC substrate body 10 is arranged such that, when the temperature of the surface of the SiC substrate body 10 and the temperature of the SiC material 40 opposite the surface are compared, the temperature on the SiC substrate body 10 side is high, and the temperature of the SiC material 40 is low (refer to FIG. 3). Figure 5). Thus, in a case where the SiC substrate body 10 and the SiC material 40 are arranged opposite to each other and heated with the SiC substrate body 10 as the high-temperature side and the SiC material 40 as the low-temperature side, the raw material is transported from the SiC substrate body 10 to the SiC material 40, and the SiC substrate body 10 is etched. That is, an etching space Y is formed between the SiC material 40 and the SiC substrate body 10.

[0159] (Heating furnace)

[0160] As shown in FIG. 1, the heating furnace 60 includes a main heating chamber 61 capable of heating a processed object (the SiC substrate body 10 or the like) to a temperature of 1,000°C or higher and 2,300°C or lower, a preheating chamber 62 capable of preheating the processed object to a temperature of 500°C or higher, a high-melting-point container 70 capable of housing the main container 50, and a moving device 63 (moving stage) capable of moving the high-melting-point container 70 from the preheating chamber 62 to the main heating chamber 61. Figure 6

[0161] The main heating chamber 61 is formed in a regular hexagon in a plan view, and the high-melting-point container 70 is arranged inside the main heating chamber 61.

[0162] A heater 64 (mesh heater) is provided inside the main heating chamber 61. In addition, a multilayer heat-reflecting metal plate (not shown) is fixed to a side wall or a top of the main heating chamber 61. The multilayer heat-reflecting metal plate is configured to reflect heat of the heater 64 toward a substantially central portion of the main heating chamber 61.

[0163] Thus, inside the main heating chamber 61, the heater 64 is arranged so as to surround the high-melting-point container 70 housing the processed object, and the multilayer heat-reflecting metal plate is arranged outside the heater 64, so that the temperature can be increased to 1,000°C or higher and 2,300°C or lower.

[0164] In addition, as the heater 64, for example, a resistance heating type heater or a high-frequency induction heating type heater can be used.

[0165] In addition, the heater 64 can also adopt a structure capable of forming a temperature gradient inside the high-melting-point container 70. For example, the heater 64 can also be configured to be provided with a plurality of heaters on the upper side. In addition, the heater 64 can also be configured to have a width that becomes larger as it goes toward the upper side. Alternatively, the heater 64 can also be configured to be capable of increasing the supplied electric power as it goes toward the upper side.

[0166] In addition, to the main heating chamber 61, a valve 65 for vacuum formation that performs evacuation of the inside of the main heating chamber 61, a valve 66 for inert gas injection that introduces an inert gas into the inside of the main heating chamber 61, and a vacuum gauge 67 that measures a degree of vacuum of the inside of the main heating chamber 61 are connected.

[0167] ​The vacuum forming valve 65 is connected to a vacuum pump (not shown) that evacuates the main heating chamber 61 to form a vacuum. By the vacuum forming valve 65 and the vacuum pump, the degree of vacuum in the main heating chamber 61 can be adjusted to, for example, 10 Pa or less, more preferably 1 Pa or less, and further preferably 10 Pa or less. As the vacuum pump, a turbo molecular pump can be exemplified. -3

[0168] The inert gas injection valve 66 is connected to an inert gas supply source (not shown). By the inert gas injection valve 66 and the inert gas supply source, the inert gas can be introduced into the main heating chamber 61 in the range of 10 Pa to 10,000 Pa. As the inert gas, Ar, He, N2, or the like can be selected. -5

[0169] Further, the inert gas injection valve 66 is a dopant gas supply device that can supply a dopant gas into the main vessel 50. That is, by selecting a dopant gas (for example, N2or the like) as the inert gas, the dopant concentration of the growth layer can be adjusted.

[0170] The preheating chamber 62 is connected to the main heating chamber 61 and is configured to move the high melting point container 70 by the moving device 63. In addition, the preheating chamber 62 of the present embodiment is configured to be warmed by the waste heat of the heater 64 of the main heating chamber 61. For example, in a case where the main heating chamber 61 is warmed to 2,000°C, the preheating chamber 62 is warmed to about 1,000°C, and the degassing treatment of the object to be processed (the SiC substrate body 10, the main vessel 50, the high melting point container 70, and the like) can be performed.

[0171] The moving device 63 is configured to place the high melting point container 70 and can move between the main heating chamber 61 and the preheating chamber 62. Since the transfer between the main heating chamber 61 and the preheating chamber 62 by the moving device 63 is completed in at least about 1 minute, the warming and cooling at 1 to 1,000°C / min can be achieved.

[0172] Thus, since rapid warming and rapid cooling can be performed, the surface shape that does not have a low temperature growth history in the warming and the cooling in a conventional device can be observed.

[0173] Further, in the present embodiment, the preheating chamber 62 is disposed below the main heating chamber 61, but is not limited thereto and can be disposed in any direction. Figure 6

[0174] Further, the moving device 63 according to the present embodiment is a moving stage that places the high melting point container 70. From the contact portion of the moving stage and the high melting point container 70, a small amount of heat is released. Thereby, a temperature gradient can be formed in the high melting point container 70 (and in the main vessel 50). ​​​

[0175] That is, in the heating furnace 60 of the present embodiment, since the bottom of the high melting point container 70 is in contact with the moving table, the temperature gradient is set so that the temperature decreases from the upper container 71 of the high melting point container 70 toward the lower container 72. It is desirable that this temperature gradient is formed in the front-back direction of the SiC substrate body 10.

[0176] Further, as described above, the temperature gradient can also be formed by the structure of the heater 64. Further, it can also be configured so that the temperature gradient can be reversed by this heater 64.

[0177] (High melting point container)

[0178] It is preferable that the heating furnace 60 forms an atmosphere containing Si elements, and that the main body container 50 can be heated in this atmosphere. The atmosphere containing Si elements in the heating furnace 60 according to the present embodiment is formed using the high melting point container 70 and the Si vapor supply source 74.

[0179] In addition, as long as it is a method that can form an atmosphere containing Si elements around the main body container 50, it is of course possible to adopt.

[0180] The high melting point container 70 is configured to contain a high melting point material. For example, C which is a general heat resistant member, W, Re, Os, Ta, Mo which are high melting point metals, Ta9C8, HfC, TaC, NbC, ZrC, Ta2C, TiC, WC, MoC which are carbides, HfN, TaN, BN, Ta2N, ZrN, TiN which are nitrides, HfB2, TaB2, ZrB2, NB2, TiB2 which are borides, and polycrystalline SiC, etc. can be exemplified.

[0181] This high melting point container 70 is a fitting container including an upper container 71 and a lower container 72 which can be fitted to each other like the main body container 50, and is configured to be able to accommodate the main body container 50. A minute gap 73 is formed at the fitting portion of the upper container 71 and the lower container 72, and is configured to be able to perform evacuation (vacuuming) inside the high melting point container 70 from this gap 73.

[0182] It is preferable that the high melting point container 70 has a Si vapor supply source 55 which is able to supply a vapor pressure of a gas phase species containing Si elements into the high melting point container 70. The Si vapor supply source 55 can be exemplified by a solid Si (a single crystal Si sheet, Si particles of Si powder, etc.), a Si compound, as long as it is a structure that generates Si vapor inside the high melting point container 70 at the time of heating.

[0183] In the SiC substrate manufacturing apparatus according to the present embodiment, TaC is adopted as the material of the high melting point container 70, and a tantalum silicide is adopted as the Si vapor supply source 55. That is, as shown in FIG. 6, the high melting point container 70 is configured to contain TaC, and the Si vapor supply source 55 is configured to contain a tantalum silicide.Figure 4 and Figure 5 As shown in FIG. 1, a tantalum silicide layer is formed on the inside of the high melting point container 70, and is configured to supply Si vapor from the tantalum silicide layer into the container at the time of heating, thereby forming a Si vapor pressure environment.

[0184] Further, as long as a structure that forms a vapor pressure of a gas phase species containing the Si element in the high melting point container 70 at the time of heating is adopted.

[0185] Hereinafter, Embodiment 1 will be described more specifically by citing an example.

[0186] Embodiment

[0187] <Embodiment 1: Movement of Strained Layer>

[0188] The SiC substrate body 10 after the slicing step S3 was housed in the main container 50 and the high melting point container 70 (refer to FIG. 1), and heat treatment was performed under the following heat treatment conditions. In this Embodiment 1, the main container 50 was formed of polycrystalline SiC, and thus the main container 50 itself functions as the SiC material 40 (Si element supply source and C element supply source). Figure 7

[0189] [SiC Substrate Body 10]

[0190] Polymorphic form: 4H-SiC

[0191] Substrate size: 10 mm in lateral width x 10 mm in longitudinal width x 0.45 mm in thickness

[0192] Deviation direction and deviation angle: 4° deviation in <11-20> direction

[0193] Heat treatment surface: (0001) plane

[0194] Depth of strained layer 12: 3.5 μm

[0195] Further, the depth of the strained layer 12 was confirmed by the SEM-EBSD method. Further, the strained layer 12 can also be confirmed by TEM, μXRD, and Raman spectroscopy.

[0196] [Main Container 50]

[0197] Material: Polycrystalline SiC

[0198] Container size: 60 mm in diameter x 4 mm in height

[0199] Material of substrate holding tool 54: Single crystal SiC

[0200] Distance of SiC substrate body 10 from the bottom surface of main container 50: 2 mm ​

[0201] [High melting point container 70]

[0202] Material: TaC

[0203] Container size: diameter 160 mm x height 60 mm

[0204] Si vapor supply source 74 (Si compound): TaSi2

[0205] [Heat treatment conditions]

[0206] The SiC substrate body 10 configured under the above conditions was subjected to heat treatment under the following conditions.

[0207] Heating temperature: 1500°C

[0208] Heating time: 10 h

[0209] Etching amount: 40 nm

[0210] Temperature gradient: 1°C / mm

[0211] Main heating chamber vacuum degree: 10 -5 Pa

[0212] [Measurement of strain layer using SEM-EBSD method]

[0213] The lattice strain of the SiC substrate body 10 can be found by comparing with a reference lattice serving as a reference. As a means of measuring this lattice strain, for example, the SEM-EBSD method can be used. The SEM-EBSD method is a method capable of measuring strain of a small region in a scanning electron microscope (SEM) based on Kikuchi diffraction patterns obtained by electron backscattering (Electron Back Scattering Diffraction: EBSD). In this method, by comparing the diffraction pattern of the reference lattice serving as a reference with the diffraction pattern of the measured lattice, the lattice strain amount can be found.

[0214] As the reference lattice, for example, a reference point is set in a region where it is considered that no lattice strain occurs. That is, it is desirable to configure the reference point in the region of the bulk layer 11. Generally, it is a matter of course that the depth of the strain layer 12 is about 10 pm. Therefore, as long as the reference point is set at a position of a depth of about 20 to 35 pm which is considered to be sufficiently deep than the strain layer 12.

[0215] Next, the diffraction pattern of the lattice at the reference point is compared with the diffraction pattern of the lattice of each measurement region measured at a nanoscale pitch. Thereby, the lattice strain amount of each measurement region with respect to the reference point can be calculated.

[0216] Furthermore, the case of setting a reference lattice as a reference point that is considered to be free from lattice strain is shown, but of course it is also possible to use an ideal lattice of single-crystal SiC as a reference, or a lattice that occupies most (e.g., more than half) of the surface of the measurement region as a reference.

[0217] The presence or absence of strain layer 12 can be determined by measuring the presence of lattice strain using the SEM-EBSD method. That is, when strain is introduced due to processing damage, lattice strain is generated at the SiC substrate 10, and stress is observed using the SEM-EBSD method.

[0218] The strain layer 12 present on the SiC substrate 10 of Example 1 before and after the strain layer thinning step S1 was observed using SEM-EBSD. The results are shown in... Figure 8 (a) and Figure 8 As shown in (b) of the document.

[0219] In addition, in this measurement, the cross-section of the SiC substrate 10 after being cut open before and after the strain layer thinning step S1 of Example 1 was measured using a scanning electron microscope under the following conditions.

[0220] SEM apparatus: Zeiss Merline

[0221] EBSD Analysis: TSL Solutions OIM Crystal Orientation Analysis System

[0222] Accelerating voltage: 15kV

[0223] Probe current: 15nA

[0224] Step size: 200nm

[0225] Reference point R depth: 20μm

[0226] Figure 8 (a) is a cross-sectional SEM-EBSD image of the SiC substrate 10 before the strain layer thinning step S1 in Example 1.

[0227] Such as Figure 8 As shown in (a), a lattice strain with a depth of 3.5 μm was observed in the SiC substrate 10 before the strain layer thinning step S1. This lattice strain was introduced during the slicing step S3, indicating the presence of the strain layer 12. Furthermore, in this… Figure 8 Compressive stress was observed in (a) of the sample.

[0228] Figure 8(b) is a cross-sectional SEM-EBSD imaging image of the SiC substrate body 10 after the strain layer thinning step S1 in Example 1.

[0229] As shown in (b) in the figure, after the strain layer thinning step S1, a lattice strain of a depth of 1.3 μm was observed in the SiC substrate body 10. Since the etching amount at the time of heat treatment was 40 nm, it was found that the strain layer 12 moved / concentrated to the surface side by about 2.2 μm. Further, by extending the heating time, the strain layer 12 can be further moved to the surface side. Figure 8

[0230] Thus, by performing heat treatment on the SiC substrate body 10 in the quasi-closed space containing the Si element supply source and the C element supply source, the strain layer 12 can be moved / concentrated to the surface side of the SiC substrate body 10.

[0231] According to the present application, by including the strain layer thinning step S1, the region removed as a material loss in the conventional method can be reduced / suppressed.

[0232] Explanation of Reference Numerals

[0233] 10 SiC substrate body 11 bulk layer 12 strain layer

[0234] 20 reference depth 30 SiC substrate 40 SiC material

[0235] 50 main vessel 51 upper vessel 52 lower vessel

[0236] 53 gap 54 substrate holding tool 55 Si vapor supply source

[0237] 60 heating furnace 61 main heating chamber 62 preheating chamber

[0238] 63 moving device 64 heater 65 vacuum forming pump

[0239] 66 inert gas injection valve 67 vacuum gauge

[0240] 70 high melting point vessel 71 upper vessel 72 lower vessel

[0241] 73 gap 74 Si vapor supply source

[0242] X crystal growth space Y etching space

[0243] S1 strain layer thinning step S2 strain layer removing step

[0244] S3 slicing step S4 etching step

[0245] I crystal ingot​

Claims

1. A method for manufacturing a SiC substrate, comprising: The strain layer thinning step involves moving the strain layer of the SiC substrate to the surface side to thin the strain layer. as well as The wet etching step involves wet etching the surface of the SiC substrate. The strain layer thinning step is a step of thermally etching the SiC substrate within a main container made of SiC material.

2. The method for manufacturing a SiC substrate according to claim 1, wherein, Includes a strain layer removal step to remove the strain layer. The strain layer thinning step involves moving the strain layer after the strain layer thinning step to a surface side closer to the surface than the reference depth, while setting the depth of the strain layer before the strain layer thinning step as a reference depth. The strain layer removal step is a step of removing at least a portion of the strain layer that is closer to the surface side than the reference depth.

3. The method for manufacturing a SiC substrate according to claim 2, wherein, The strain layer removal step is chemical mechanical polishing.

4. The method for manufacturing a SiC substrate according to claim 2, wherein, The strain layer removal step is a thermal etching method.

5. The method for manufacturing a SiC substrate according to any one of claims 2 to 4, wherein, It also includes a slicing step of slicing the crystal ingot to obtain the SiC substrate. The slicing step is a step to obtain a SiC substrate, the thickness of which is less than 100 μm thicker than the thickness of the SiC substrate after the strain layer removal step.

6. The method for manufacturing a SiC substrate according to claim 5, wherein, The slicing step is the step of obtaining a SiC substrate, the thickness of which is less than 50 μm more than the thickness of the SiC substrate after the strain layer removal step.

7. The method for manufacturing a SiC substrate according to claim 1, wherein, In the etching step, the etching solution includes one or more selected from the group consisting of potassium hydroxide molten liquid, hydrofluoric acid-containing solution, potassium permanganate-based solution and tetramethylammonium hydroxide.

8. The method for manufacturing a SiC substrate according to claim 7, wherein, This includes the slicing step of slicing a crystal ingot to obtain a SiC substrate, and The process includes, in sequence, the slicing step, the etching step, and the strain layer thinning step.

9. The method for manufacturing a SiC substrate according to any one of claims 1 to 4, wherein, The heating temperature for the strain layer thinning step is above 1400°C and below 1600°C.

10. A method for manufacturing a SiC substrate, comprising: The slicing step involves slicing the crystal ingot to obtain the SiC substrate. The strain layer thinning step involves moving the strain layer of the SiC substrate to the surface side to thin the strain layer. as well as The strain layer removal step removes the strain layer. The strain layer thinning step is a step of thermally etching the SiC substrate within a main container made of SiC material. Furthermore, it involves moving the strain layer after the strain layer thinning step to a surface depth greater than the reference depth, while setting the depth of the strain layer before the strain layer thinning step as a reference depth. The strain layer removal step is a step of removing at least a portion of the strain layer that is closer to the surface side than the reference depth. The slicing step is a step to obtain a SiC substrate, the thickness of which is less than 100 μm thicker than the thickness of the SiC substrate after the strain layer removal step.

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