Base, apparatus and method for manufacturing SiC single crystal
By designing locally thinned gas permeation regions and void structures on the SiC single crystal growth substrate, the porosity problem caused by the binder heating gas was solved, and the growth of high-quality, large-diameter SiC single crystals was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- RESONAC CORP
- Filing Date
- 2019-07-12
- Publication Date
- 2026-05-12
AI Technical Summary
During the growth of SiC single crystals, the gas generated by heating the binder causes pores to form between the substrate and the seed crystal, resulting in macroscopic defects and reduced adhesion. In particular, it is difficult to effectively remove side gas in the manufacturing of large-diameter SiC wafers.
A base with a locally thinned gas permeable area is designed to effectively expel the gas generated when the adhesive is heated, thus preventing the formation of pores. Porous carbon or glassy carbon materials are used as the base material, and the gas permeable area and pore structure are combined to ensure smooth gas discharge.
It effectively reduces macroscopic defects, improves the quality and adhesion of SiC single crystals, prevents the peeling of SiC single crystals and seeds during growth, and ensures high-quality growth of large-diameter SiC wafers.
Smart Images
Figure CN110735183B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a substrate for supporting the growth of SiC single crystals, an apparatus for manufacturing SiC single crystals equipped with the substrate, and a manufacturing method thereof.
[0002] This application claims priority based on Japanese Patent Application No. 2018-135092, filed on July 18, 2018, the contents of which are incorporated herein by reference. Background Technology
[0003] Silicon carbide (SiC), as a semiconductor material, is known to have a wider bandgap and superior voltage withstand and thermal conductivity compared to silicon (Si), which is widely used as a substrate for devices. Therefore, applications of silicon carbide in power devices, high-frequency devices, and high-temperature operating devices are expected.
[0004] Semiconductor devices utilizing silicon carbide (SiC) employ SiC epitaxial wafers on which epitaxial films have been formed. The epitaxial film, deposited on the SiC wafer using Chemical Vapor Deposition (CVD), becomes the active region of the SiC semiconductor device. The active region of the epitaxial film inherits and / or transforms crystal defects from the SiC wafer into other crystal defects, thus being affected by the quality of the SiC wafer. Therefore, high-quality SiC wafers free of defects are required.
[0005] SiC wafers are made by cutting ingots of SiC single crystals. SiC single crystals are generally manufactured using the sublimation method. The sublimation method involves placing a seed crystal (silicon crystal) made of SiC single crystal on a substrate placed within a graphite crucible, and heating the crucible to supply sublimation gas, which sublimates from the raw material powder within the crucible, to the seed crystal, causing the seed crystal to grow into a larger SiC single crystal. During the growth of the SiC single crystal, the seed crystal is fixed to the substrate using a binder. As a binder, carbon binders containing organic solvents are commonly used (Patent Document 1).
[0006] Prior art literature
[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-193494 Summary of the Invention
[0008] During the curing process of the binder, gas is generated from the heated carbon binder. If this gas creates a pore between the substrate and the seed crystal, macroscopic defects (through defects) extend from this pore and reach the growing SiC single crystal. Therefore, the adhesion between the growing SiC single crystal and the seed crystal and the substrate sometimes decreases, causing them to peel off. Even without peeling, the grown SiC single crystal contains macroscopic defects, resulting in a decrease in quality.
[0009] If a small-diameter seed crystal is used, the gas can be released from the side not covered by the seed crystal by applying a weight to the seed crystal before growing the SiC single crystal and pressurizing it, and / or by performing a vacuum degassing treatment. However, due to recent needs, when manufacturing large-diameter SiC wafers, large-diameter seed crystals are correspondingly used. In this case, the gas generated near the center of the binder layer is difficult to release from the side.
[0010] The present invention was made in view of the following situation, and its object is to provide a base that can remove gas generated from the heated binder when the seed crystals are fixed with a binder.
[0011] (1) In one embodiment of the present invention, the base is a base for a seed crystal for crystal growth. The main surface of the side on which the seed crystal is bonded is flat. The base has a gas permeable region, which is a region formed by locally thinning the thickness from the main surface of the side.
[0012] (2) In the base described in (1), preferably, the thickness of the gas permeation area is 1 mm or more and less than 5 mm.
[0013] (3) In the base described in either (1) or (2), preferably, the thickness of the gas permeation region increases as it moves away from the center.
[0014] (4) In any of the bases described in (1) to (3), preferably, the area outside the gas permeation area includes a portion with a thickness of 10 mm or more.
[0015] (5) In any of the bases described in (1) to (4), preferably, in a top view in the thickness direction, when the distance from the center to the outer periphery is set as r, the gas permeation area is included in the range of a distance of (r / 2) from the center.
[0016] (6) In another embodiment of the present invention, the base is a base for a seed crystal for crystal growth. The main surface of the side on which the seed crystal is bonded is flat. The base has a gas permeable area, which is a region that extends along the depth direction in a part of the main surface on the side. There is a gap communicating with the outside in a direction inside the gas permeable area.
[0017] (7) In the base described in (6), preferably, the gap is formed at a position where the distance from the main surface on one side is more than 1 mm and less than 5 mm.
[0018] (8) The SiC single crystal manufacturing apparatus of one aspect of the present invention includes the base described in any one of (1) to (7).
[0019] (9) The method for manufacturing SiC single crystal in one aspect of the present invention involves manufacturing SiC single crystal using a substrate described in any one of (1) to (7), attaching the seed crystal to the main surface of one side of the substrate using an adhesive, and pressing the seed crystal against the substrate side during a heating process for curing the adhesive.
[0020] (10) The method for manufacturing SiC single crystal described in (9) preferably includes a step of filling the recess formed in the substrate after the heating step.
[0021] The base of the present invention has a gas permeable region formed by local thinning. Therefore, when the seed crystals are fixed with an adhesive, the gas generated from the adhesive when it is heated and cured can be released to the outside through the gas permeable region and removed. Attached Figure Description
[0022] Figure 1 This is a longitudinal cross-sectional view of a SiC single crystal manufacturing apparatus equipped with the base in the first embodiment of the present invention.
[0023] Figure 2A It is Figure 1 A magnified image of the area surrounding the substrate in the SiC single crystal manufacturing apparatus.
[0024] Figure 2B Viewed from above the seed crystal. Figure 2A A diagram of the base.
[0025] Figure 3A This is a cross-sectional view schematically showing the structure around the base when using the base in the second embodiment of the present invention.
[0026] Figure 3B Viewed from above the seed crystal. Figure 3A A diagram of the base.
[0027] Figure 4A This is a cross-sectional view schematically showing the structure around the base when using the base in the third embodiment of the present invention.
[0028] Figure 4B This is a cross-sectional view schematically showing the structure around the base when using the base in the third embodiment of the present invention.
[0029] Figure 5A This is a cross-sectional view schematically showing the structure around the base when using the base in the fourth embodiment of the present invention.
[0030] Figure 5B Viewed from above the seed crystal. Figure 5A A diagram of the base.
[0031] Explanation of reference numerals in the attached figures
[0032] 100···SiC Single Crystal Manufacturing Equipment
[0033] 101··· Crucible
[0034] 102··· Seed Crystal
[0035] 103, 113, 123, 133... base
[0036] 103a···Main face on one side of the base
[0037] 104···Raw Materials
[0038] 105··· Adhesive layer
[0039] 106, 136... Gas permeation areas
[0040] Thickness of the gas permeation zone: 106T, 136T...
[0041] 107, 137... gap
[0042] D··· Depth direction
[0043] G, G1, G2... gases
[0044] R··· area Detailed Implementation
[0045] The present invention will now be described in detail with appropriate reference to the accompanying drawings. To facilitate understanding of the features of the invention, the drawings used in the following description may sometimes be enlarged representations of key features, and the dimensional ratios of the constituent elements may sometimes differ from the actual dimensions. Furthermore, the materials, dimensions, etc., illustrated in the following description are examples, and the invention is not limited thereto; appropriate modifications can be made to achieve the desired effects.
[0046] <First Implementation Method>
[0047] Figure 1 This is a cross-sectional view of a SiC single crystal manufacturing apparatus 100 equipped with the base as described in the first embodiment of the present invention. The SiC single crystal manufacturing apparatus 100 includes at least: a crucible 101, and a base (support member) 103 for a seed crystal 102 for crystal growth disposed at one end of the crucible 101, and a raw material 104 housed at the other end of the crucible 101. The SiC single crystal manufacturing apparatus 100 may further include a coil and a tapered guide (cylindrical member), the coil surrounding the outer wall of the crucible 101, and the tapered guide (cylindrical member) disposed within the crucible with an expanded diameter from the base 103 side towards the raw material 104 side to guide sublimation gas towards the seed crystal position.
[0048] Figure 2A It is Figure 1 A magnified view of the region R surrounding the substrate 103 in the SiC single crystal manufacturing apparatus 100. On the main surface 103a side of the substrate 103 (… Figure 1 The raw material 104 is inserted into a layer (adhesive layer) 105, which is composed of adhesive, to bond (fix) the seed crystal 102.
[0049] The base 103 is made of a carbon forming material based on graphite, porous carbon, glassy carbon, or other carbon-based materials. A carbon binder containing organic solvents is used as the binder.
[0050] During the process of bonding the seed crystal 102 to the substrate 103, the adhesive applied to the substrate 103 needs to be heated to cure it, and gas G is generated from the heated adhesive. This gas G is contained in at least commonly used adhesives, with benzene, phenol, etc. as the main components.
[0051] In the base 103, the main surface 103a on one side of the seed crystal 102 is flat and has a region (gas permeable region) 106 where gas can easily pass through. The region (gas permeable region) 106 is formed with a localized thinning from the main surface 103a on one side. That is, the gas permeable region 106 is thinner than other regions. Preferably, the thickness 106T of the gas permeable region 106 is 1 mm or more and less than 5 mm.
[0052] Directly below gas permeation area 106 ( Figure 1 The opposite side of the raw material 104 becomes a void (cavity) 107, which is surrounded by a region that is thicker than the gas permeable region 106 and makes it difficult for gas to pass through. This void 107 can also be viewed as a recess (cavity) when viewed from the main surface 103b on the other side of the base.
[0053] The gap 107 can be any shape that communicates with the outside. From the viewpoint of facilitating the smooth flow of gas, a shape with less bending is preferred, and a shape that extends along the thickness direction of the base 106 is even more preferred. Figure 2A In the example shown, a gap 107 extends in a straight line in the thickness direction of the base 106.
[0054] When the thickness 106T of the gas permeation region 106 is less than 1 mm, the binder and gas seep out together from the gas permeation region 106, forming an area with less binder, thereby reducing the adhesion between the substrate and the seed crystal. Furthermore, in this case, cracking sometimes occurs, and the flatness of the main surface 103a on one side is easily disrupted, becoming an obstacle to crystal growth. Moreover, when the thickness 106T is 5 mm or more, gas permeability decreases, making it difficult to remove gas from the target binder layer 105; as a result, the effect of suppressing macroscopic defects diminishes.
[0055] The average thickness of the adhesive layer 105 outside the gas-permeable region 106 (non-gas-permeable region) exceeds 5 mm, and from the viewpoint of maintaining the strength of the support member as a seed crystal, it is preferable to include a portion with a thickness of 10 mm or more. Preferably, the portion with a thickness of 10 mm or more accounts for more than 20% of the non-gas-permeable region.
[0056] Figure 2B It is from above seed crystal 102. Figure 2A A top view of the base 103. Figure 2A It was cut at the position of line AA'. Figure 2B Cross-sectional view of the base 103 and seed crystal 102.
[0057] In the adhesive layer 105, the gas G1 generated near the outer periphery 105a is released laterally (in a direction perpendicular to the thickness direction), but the gas G2 generated near the central portion 105b tends not to flow laterally and remains. To remove such residual gas, the gas permeation region 106 is preferably located near the central portion 105b, specifically at a distance r from the center C to the outer periphery, preferably at a distance of r / 2 or less from the center C, and more preferably at a distance of r / 4 or less. (In this specification, the center of the seed crystal, adhesive layer, and substrate in the top view in the thickness direction is collectively referred to as the center C.)
[0058] exist Figure 2B In the top view, the area of the gas permeable region 106 is preferably 1% to 80% of the area of the seed crystal 106. When it is greater than 80% of the area of the seed crystal 102, the proportion of the thin portion in the substrate 103 becomes higher, making it difficult to maintain flatness. When it is less than 1% of the area of the seed crystal 102, the gas permeability becomes lower, and the effect of suppressing the generation of macroscopic defects becomes smaller.
[0059] [Manufacturing methods for SiC single crystals]
[0060] The method for manufacturing SiC single crystals using the base 103 of this embodiment will be described.
[0061] First, an adhesive layer 105 is formed by applying an adhesive to the portion of the main surface 103a on one side of the base of this embodiment where the seed crystal 102 is placed. Next, the seed crystal is attached to the adhesive layer 105.
[0062] In this state, the adhesive layer 105 is heated to cure the adhesive in the adhesive layer 105 (heating process). Preferably, the heating temperature is approximately 200°C or higher and 2000°C or lower, and the total heating time is approximately 3 hours or higher and 100 hours or lower.
[0063] During heating, gas is generated inside the adhesive layer 105, but according to the structure of this embodiment, the generated gas can be automatically released to the outside through the gas permeation area.
[0064] In the heating process described above, a load can be applied to the seed crystal 102 to press it toward the base 103. This forces the gas in the binder layer 105, which contributes to macroscopic defect formation, to be expelled to the outside. Preferably, the load in this case is approximately 6 g / cm³. 2 above.
[0065] Next, as Figure 1 As shown, a base 103 to which the seed crystal 102 is attached is provided such that the seed crystal 102 is exposed in the internal space of the crucible 101, and the gap 107, which is in contact with the gas permeation region 106, is connected to the external space of the crucible 101. In this state, the crucible 101 is heated using a heating unit such as a coil. As a result, a raw material gas is generated from the raw material 104, and this raw material gas is supplied to the seed crystal 102 attached to the base 103. By supplying the raw material gas to the seed crystal 102, a SiC single crystal is grown on the surface of the seed crystal 102, forming a SiC single crystal ingot.
[0066] Furthermore, after the gas in the adhesive layer 105 is released, the voids 107 can be filled with a predetermined component in a manner that the presence of voids 107 does not affect the temperature environment for crystal growth (filling process). Preferably, the component to be filled is a component having the same properties as the constituent components of the base 103.
[0067] As described above, the base 103 in this embodiment has a gas permeable region 106 formed by local thinning. Therefore, when the seed crystal 102 is fixed with an adhesive, the gas G generated from the adhesive when it is heated and cured can be released to the outside through the gas permeable region 106.
[0068] Therefore, the number of macroscopic defects caused by pore elongation from gas G can be reduced, and the decrease in the adhesion between the substrate 103 and the seed crystal 102 caused by macroscopic defects can be suppressed. As a result, high-quality SiC single crystals can be obtained that prevent the growing SiC single crystal and the seed crystal 102 from peeling off from the substrate 103 and suppress the influence of macroscopic defects.
[0069] In this embodiment, the thickness of the base 103 outside the gas permeation area 106 exceeds 5 mm, thus avoiding problems such as cracking and easy destruction of the flatness of the main surface 103a on the side where the seed crystal 102 adheres.
[0070] <Second Implementation Method>
[0071] Figure 3A When using the base 113 in the second embodiment of the present invention, and with Figure 2A Similarly, a cross-sectional view of the peripheral structure of the base 113 is schematically shown. The base 113 of this embodiment has multiple locally thinned gas permeable regions 116. Other structures are the same as those of the first embodiment, and the parts corresponding to those in the first embodiment are indicated by the same reference numerals regardless of shape. In this embodiment, at least the same effects as those of the first embodiment can be obtained.
[0072] When multiple gas-permeable regions 116 are configured to increase the area of the gas-permeable regions, it is preferable that the gas-permeable regions can also increase proportionally. However, from the viewpoint of balancing flatness and gas permeability, it is preferable that the total area of the multiple gas-permeable regions 106 is 1% or more and 80% or less of the area of the seed crystal 102.
[0073] By distributing the gas permeation regions 106 in multiple locations, stresses such as tension that concentrate at each location due to changes in the thermal environment can be reduced. Therefore, when the total area of the multiple gas permeation regions 106 is the same as the area of the gas permeation regions 106 in the first embodiment, the maximum gas permeation amount of the base 113 in this embodiment is the same, but the strength can be improved compared to the base 103 in the first embodiment, corresponding to stress dispersion.
[0074] Figure 3B This is a plan view of the main surface 113a side of the base 113 in this embodiment. Figure 3A It was cut at the BB' line. Figure 3B Cross-sectional view of base 113 and seed crystal 102.
[0075] From the viewpoints of efficiently allowing gas to permeate the adhesive layer 105, uniformly reducing the amount of gas in the adhesive layer 105 throughout the entire area, and eliminating the anisotropy of stress applied to the base 113, it is preferable that the gas permeation region 106 is configured with high circumferential symmetry relative to the center C of the main surface 113a on one side. As such a configuration, examples include those forming a regular polygon (…). Figure 3B The arrangement of the positions of multiple vertices of a regular hexagon (within which the polygon is located) and the position of the center point of the regular polygon. In this case, the center point of the regular polygon corresponds to the center C of the main face 113a on one side.
[0076] Furthermore, less gas is released laterally near the central portion 105b of the adhesive layer, resulting in a higher residual amount compared to gas generated near the outer peripheral portion 105a. Therefore, from the viewpoint of uniformly reducing the gas in the adhesive layer 105 throughout the entire area, it is more preferable to have a gas permeation area overlapping with the central portion 105b than a gas permeation area overlapping with the outer peripheral portion 105a.
[0077] In the first embodiment, gas G1 generated near the outer periphery of the binder layer 105 during crystal growth is released laterally and introduced into the crucible 101. In contrast, in this embodiment, by forming a gas permeation region 106 overlapping the outer periphery of the binder layer 105, at least a portion of the gas G1 generated near the outer periphery 105a can be discharged outside the crucible 101 via the gas permeation region 106. As a result, during crystal growth, the amount of gas G1 laterally introduced into the crucible 101 from the binder layer 105 can be reduced, thus minimizing the impact of gas G1 on crystal growth.
[0078] <Third Implementation Method>
[0079] Figure 4A , 4B When using the base 123 in the third embodiment of the present invention, and with Figure 2A Similarly, a cross-sectional view of the peripheral structure of the base 123 is schematically shown. In the base 123 of this embodiment, the thickness 106T of the gas permeation region increases as it moves away from the center C in the top view in the thickness direction. The increase in thickness 106T can be continuous or discontinuous. In the latter case, more gas permeates near the relatively thin central portion.
[0080] Furthermore, since the thickness 106T of the gas permeation region decreases with distance from the center C, more gas permeates near the relatively thin outer periphery. Other structures are the same as in the first embodiment, and the parts corresponding to those in the first embodiment are indicated by the same reference numerals regardless of shape. In this embodiment, at least the same effects as in the first embodiment can be obtained.
[0081] Figure 4A The following situation is shown: the increase in thickness 106T is continuous, the surface 106b of the gas permeation region 106 opposite to the seed crystal 102 is depicted as a gentle curve in the cross-sectional view, and is proportional to the distance from the center C away from the main surface 103a on one side.
[0082] Figure 4B The following situation is shown: the increase in thickness 106T is continuous, the surface 106b of the gas permeation region 106 opposite to the seed crystal 102 is inclined in a straight line in the cross-sectional view, and is proportional to the distance from the center C away from the main surface 103a on one side.
[0083] In this embodiment, the gap 107 in contact with the gas permeation region 106 widens as it moves away from the gas permeation region 106. Therefore, the interaction (pressure) between the gases G1 released from the gas permeation region 106 weakens as it moves away from the gas permeation region 106. Consequently, the gas G1 released from the gas permeation region 106 has a higher probability of leaving the gas permeation region 106. As a result, the permeation of gas G1 in the thickness direction of the gas permeation region 106 becomes more favorable.
[0084] <Fourth Implementation Method>
[0085] Figure 5A When using the base 133 in the third embodiment of the present invention, and with Figure 2A Similarly, a cross-sectional view of the peripheral structure of the base 133 is schematically shown. In this embodiment, the shapes of the gas permeation region 106 and the gap 107 in the base 133 differ from those in the first embodiment. In this embodiment, a gas permeation region 136 extends (extends) along the depth direction D in a portion of the main surface 133a on one side of the base 133, and has a predetermined thickness, allowing gas to permeate in the depth direction D. A gap 137 communicating with the outside is located further inside (deeper) than the gas permeation region 136. Other structures are the same as in the first embodiment, and the same reference numerals are used to denote the parts corresponding to those in the first embodiment, regardless of shape.
[0086] In this embodiment, the area sandwiched between the gap 137 and the main surface 133a on one side becomes the gas permeable area 136. Preferably, the gap 137 is formed at a position where the distance (depth) from the main surface 133a on one side is 1 mm or more and less than 5 mm. That is, preferably, the thickness 136T of the gas permeable area is 1 mm or more and less than 5 mm.
[0087] When the thickness 136T of the gas permeation region is less than 1 mm, the binder and gas seep out together from the gas permeation region 136, forming an area with less binder, and the adhesion between the substrate and the seed crystal decreases. In addition, in this case, cracking sometimes occurs, and the flatness of the main surface 133a on one side is easily disrupted, becoming an obstacle to crystal growth. Furthermore, when the thickness 136T is 5 mm or more, the gas permeability becomes lower, making it difficult to remove the gas from the binder layer 105, resulting in a smaller effect in suppressing the generation of macroscopic defects.
[0088] The gap 137 only needs to be connected to the outside of the base 133 at at least one point, but if Figure 5A As shown, the gas flows to the outside at two points. If these two points are connected, the flow of gas to the outside becomes smoother, which is therefore preferred.
[0089] Figure 5B This is a plan view of the main surface 133a of the base 133 in this embodiment. Figure 5A It was cut at the position of the DD' line. Figure 5B A cross-sectional view of the base 113 and seed crystal 102. Here, an example is given where the gas permeation region 136 is formed into a cross shape extending in four directions from the center C, and two through holes are formed in the gap 137 extending along the gas permeation region 136.
[0090] From the viewpoint of efficiently releasing gas to the outside, the more through holes the better, and the larger the inner diameter of the through holes the better. However, if the number of through holes is too large, and / or the inner diameter of the through holes is too large, the proportion of voids formed in the base 133 becomes high, making it difficult to maintain strength, and consequently, the flatness of the main surface 133a on one side is easily compromised. Therefore, the number of through holes and their inner diameter need to be determined taking into account the size of the base used.
[0091] Preferably, the through holes are arranged symmetrically with respect to the center C of the main surface 133a on one side of the base. When there are multiple through holes, it is preferable that the multiple through holes intersect at the center C at a position overlapping the central portion of the adhesive layer 105 where gas can easily remain, so that the gas permeation area 136 is concentrated. That is, it is preferable that the multiple through holes are formed in a radial pattern extending from the center C.
[0092] From the viewpoints of enabling efficient gas permeation in the adhesive layer 105, reducing the gas content in the adhesive layer 105 uniformly throughout the region, and eliminating the anisotropy of stress applied to the base 133, it is preferable that the gas permeation region 136 is configured with high circumferential symmetry relative to the center C of the main surface 133a on one side.
[0093] In the base 133 of this embodiment, a thin region is formed directly above (overlapping with) the voids present in the base 133, which becomes the gas permeation region 136. Therefore, when the seed crystal 102 is fixed with an adhesive, the gas G generated from the adhesive when it is heated and cured can be released to the outside through the gas permeation region 136 and the voids 137.
[0094] Therefore, the number of macroscopic defects that elongate from the pores due to gas G can be reduced, and the decrease in the adhesion between the substrate 103 and the seed crystal 102 caused by macroscopic defects can be suppressed. As a result, high-quality SiC single crystals can be obtained that prevent the growing SiC single crystal and the seed crystal 102 from peeling off from the substrate 133 and suppress the influence of macroscopic defects.
[0095] In this embodiment, the thickness of the base 103 outside the gas permeation area 136 exceeds 5 mm, thus avoiding problems such as cracking and easy destruction of the flatness of the main surface 103a on the side where the seed crystal 102 adheres.
Claims
1. A substrate for seed crystal growth, wherein the seed crystal is adhered to a main surface on one side of the substrate using an adhesive layer composed of an adhesive, characterized in that, The main surface of the side where the seed crystal is bonded is flat. The base has a gas permeable region, which is formed by a localized thinning of the thickness from the main surface on one side. The thickness of the gas permeation zone is greater than 1 mm and less than 5 mm. The thickness of the gas permeation zone increases with distance from the center.
2. The base according to claim 1, characterized in that, The area outside the gas permeation zone includes portions with a thickness of 10 mm or more.
3. The base according to claim 1, characterized in that, In a top view taken from the thickness direction, when the distance from the center to the outer perimeter is set as r, the gas permeation area is contained within a range of (r / 2) from the center.
4. A substrate for seed crystal growth, wherein the seed crystal is adhered to a main surface on one side of the substrate using an adhesive layer composed of an adhesive, characterized in that, The main surface of the side where the seed crystal is bonded is flat. The base has a gas permeable area, which is a region extending along the depth direction on a portion of the main surface on one side, and has a gap communicating with the outside on the inner side of the gas permeable area.
5. The base according to claim 4, characterized in that, The gap is formed at a distance of more than 1 mm and less than 5 mm from the main surface on one side.
6. An apparatus for manufacturing SiC single crystals, characterized in that, The base is provided with any one of claims 1 to 5.
7. A method for manufacturing SiC single crystals, comprising manufacturing SiC single crystals using the substrate according to any one of claims 1 to 5, characterized in that, After the seed crystal is attached to the main surface of one side of the base using an adhesive, the seed crystal is pressed against the base side during a heating process to cure the adhesive.
8. The method for manufacturing SiC single crystals according to claim 7, characterized in that, After the heating process, there is a process of filling the recess formed in the base.