Crystal growth vessel, method for manufacturing SiC single crystals, and cylindrical member

Abstract

To provide a cylindrical member capable of growing large-diameter SiC single crystals with few defects, a crystal growth vessel equipped with the same, and a method for manufacturing SiC single crystals using the same. [Solution] The crystal growth container 20 comprises a graphite crucible 24 for holding a SiC raw material 22 that is heated and sublimated using high-frequency induction heating, a base 28 for holding a seed crystal 26 for growing a SiC single crystal, and a cylindrical member 30 disposed between the graphite crucible 24 and the base 28. The cylindrical member 30 comprises a cylindrical base material made of graphite or a high-melting-point metal, and a coating made of a high-melting-point metal carbide formed on the inner surface and / or outer surface of the base material, with an inner dimension of 150 mm or more. The method for manufacturing a SiC single crystal comprises a step of growing a SiC single crystal on the surface of a seed crystal using such a crystal growth container 20.

Description

Technical Field

[0001] The present invention relates to a crystal growth vessel, a method for producing a SiC single crystal, and a cylindrical member, and more particularly, to a cylindrical member used for isolating a growth space for a SiC single crystal from an external space during growth of the SiC single crystal, a crystal growth vessel provided with such a cylindrical member, and a method for producing a SiC single crystal using such a crystal growth vessel.

Background Art

[0002] SiC single crystals are generally produced using a sublimation method. Here, the "sublimation method" (also referred to as sublimation recrystallization method or sublimation reprecipitation method) refers to a method in which a raw material for sublimation is sublimated, and the sublimed gas is reprecipitated (condensed) on the surface of a seed crystal.

[0003] Growth of a single crystal using the sublimation method is generally performed by arranging a pedestal to which a seed crystal is bonded above a crucible filled with a raw material for sublimation, and heating the seed crystal and the raw material for sublimation to a predetermined temperature using a heating device. At this time, in order to improve the heat insulation of the growth space, a heat insulating material is arranged around the crucible. Since the growth environment of single crystals is harsh, high durability is required for various members used for single crystal growth. Therefore, various proposals have conventionally been made for various members used for such single crystal growth.

[0004] For example, Patent Document 1 discloses an apparatus for producing a silicon carbide single crystal in which a tantalum carbide ring is arranged around a seed crystal. This document describes that arranging a tantalum carbide ring around a seed crystal can prevent carbon inclusions from forming on the grown crystal surface.

[0005] Patent Document 2 discloses an apparatus for producing a SiC single crystal in which a graphite guide member having a TaC coating film formed on the inner surface is arranged around a seed crystal. The document states that forming a TaC coating film on the inner surface of a graphite guide member can suppress carbon inclusions from the graphite guide member into the SiC single crystal.

[0006] Non-patent documents 1 and 2 report examples of applying TaC-coated material to cylindrical members (outer diameter of cylinder: 150 mm or less, outer diameter of crystal: approximately 100 mm) that form partitions between the raw material crucible and the crystal growth section. Non-patent document 3 also reports an example of applying TaC-coated material to the inner wall member of a growth guide.

[0007] In recent years, 150mm has become the standard size for SiC wafers used in power semiconductor applications, and is soon moving towards 200mm. Consequently, the diameter of the bulk crystals used in bulk SiC single crystal growth, as well as the diameter of the crucibles used for growth, have also increased. However, as the raw material crucibles become larger, uniform heating of the crucibles is becoming increasingly difficult. In particular, when heating raw material crucibles using high-frequency induction heating, uniform heating of large-diameter crucibles is challenging. Non-uniformity of the raw material temperature leads to uneven sublimation gas generation, resulting in reduced raw material utilization efficiency (<50%). Furthermore, non-uniformity of the raw material temperature also limits the growth height of SiC single crystals (h<30mm). [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2009-078929 [Patent Document 2] Japanese Patent Publication No. 2005-225710 [Non-patent literature]

[0009] [Non-Patent Document 1] D. Nakamura, K. Shigetoh, Fabrication of large-sized TaC-coated carbon crucibles for the low-cost sublimation growth of large-diameter bulk SiC crystals, Jpn. J. App. Phys. 56 (2017) 085504 [Non-Patent Document 2] Materials Science Forum Vols. 778-780 (2014) pp. 26-30 [Non-Patent Document 3] Journal of Crystal Growth 600 (2022) 126929 [Overview of the project] [Problems that the invention aims to solve]

[0010] The problem that this invention aims to solve is to provide a crystal growth container and a cylindrical member used therein that can grow large-diameter SiC single crystals with few defects. Another problem that the present invention aims to solve is to provide a crystal growth vessel and a cylindrical member used therein that can grow SiC single crystals with few defects, a large diameter, and a high growth height in a short time and / or at low cost. Furthermore, another problem that the present invention aims to solve is to provide a method for manufacturing SiC single crystals using such a crystal growth vessel. [Means for solving the problem]

[0011] To solve the above problems, the crystal growth vessel according to the present invention has the following configuration. (1) The crystal growth vessel is A graphite crucible for holding SiC raw materials that are heated and sublimated using high-frequency induction heating, A base for holding a seed crystal for growing a SiC single crystal, a cylindrical member disposed between the graphite crucible and the pedestal and comprises: (2) the cylindrical member comprises: a cylindrical base material made of graphite or a high-melting-point metal, and a coating film made of a high-melting-point metal carbide formed on the inner surface and / or outer surface of the base material, and comprises: an inner dimension of 150 mm or more. provided that, the "high-melting-point metal" refers to a metal having a melting point of 2000°C or higher, the "high-melting-point metal carbide" refers to a carbide containing at least one of said high-melting-point metals.

[0012] It is preferable that the wall thickness of the base material of the cylindrical member is 1.0 mm or more and 8.0 mm or less. It is preferable that the cylindrical member is composed of a fitting-type two-split member formed by fitting a semi-cylindrical member A and a semi-cylindrical member B, each having a shape obtained by splitting a cylinder in the axial direction, via split surfaces.

[0013] The method for producing a SiC single crystal according to the present invention comprises a step of growing a SiC single crystal on the surface of the seed crystal using the crystal growth vessel according to the present invention.

[0014] Furthermore, the cylindrical member according to the present invention has the following configuration. (1) The cylindrical member is used, when growing a SiC single crystal on the surface of a seed crystal by a sublimation method in which SiC raw material is heated and sublimed using high-frequency induction heating, for surrounding the space between the graphite crucible holding the SiC raw material and the pedestal holding the seed crystal. (2) The cylindrical member comprises: a cylindrical base material made of graphite or a high-melting-point metal, and a coating film made of a high-melting-point metal carbide formed on the inner surface and / or outer surface of the base material, and comprises: an inner dimension of 150 mm or more. provided that, the "high-melting-point metal" refers to a metal having a melting point of 2000°C or higher, The term "high melting point metal carbide" refers to a carbide containing at least one of the aforementioned high melting point metals. [Effects of the Invention]

[0015] When growing SiC single crystals, placing a large-diameter cylindrical member with a high-melting-point metal carbide coating on its inner and / or outer surfaces between the raw material crucible and the base allows for the growth of large-diameter SiC single crystals with fewer defects. In this case, optimizing the wall thickness of the cylindrical member allows for the rapid growth of high-growing SiC single crystals. This is thought to be because optimizing the wall thickness of the cylindrical member suppresses excessive heat generation in the cylindrical member, creating an appropriate temperature gradient between the SiC raw material and the seed crystal.

[0016] Furthermore, when a cylindrical member is placed between the graphite crucible and the base, the SiC single crystal grows to conform to the inner shape of the cylindrical member. On the other hand, high-melting-point metal carbides have a larger coefficient of thermal expansion than SiC. Therefore, if the cylindrical member is a single piece, when the growth container is cooled to room temperature after growth is complete, the SiC single crystal expands relative to the cylindrical member, which can cause the cylindrical member to crack. In contrast, by using a two-part interlocking design for the cylindrical component, damage to the cylindrical component is suppressed, allowing for repeated use. As a result, the manufacturing cost of large-diameter SiC single crystals can be reduced. [Brief explanation of the drawing]

[0017] [Figure 1] This is an axial cross-sectional view of a first specific example of a two-part interlocking member. [Figure 2] This is an axial cross-sectional view of a second specific example of a two-part interlocking member. [Figure 3] This is a schematic diagram of a single crystal manufacturing apparatus equipped with a crystal growth vessel according to the present invention. [Figure 4] This figure shows the relationship between the wall thickness of the base material of a cylindrical member and the initial growth rate. [Modes for carrying out the invention]

[0018] [Configuration 1] A crystal growth vessel having the following configuration. (1) The crystal growth vessel is A graphite crucible for holding SiC raw materials that are heated and sublimated using high-frequency induction heating, A base for holding a seed crystal for growing a SiC single crystal, A cylindrical member is placed between the graphite crucible and the base. It is equipped with. (2) The cylindrical member is A cylindrical base material made of graphite or a high melting point metal, A coating made of a high-melting-point metal carbide formed on the inner and / or outer surfaces of the substrate, Equipped with, The internal dimensions are 150mm or more. however, The aforementioned "high melting point metal" refers to a metal with a melting point of 2000°C or higher. The term "high melting point metal carbide" refers to a carbide containing at least one of the aforementioned high melting point metals.

[0019] [Configuration 2] The cylindrical member is a crystal growth container according to configuration 1, wherein the wall thickness of the base material is 1.0 mm or more and 8.0 mm or less.

[0020] [Configuration 3] The crystal growth vessel according to configuration 1 or 2, wherein the cylindrical member is a fitted two-part member formed by fitting together a semi-cylindrical member A and a semi-cylindrical member B, which have a shape obtained by dividing a cylinder in the axial direction, through the dividing surface.

[0021] [Structure 4] The aforementioned cylindrical member is (A) The semi-cylindrical member A is made up of a member having S-shaped fitting grooves formed on both outer surfaces of the fitting portion, The semi-cylindrical member B is made of a member having inverted S-shaped fitting grooves formed on both inner surfaces of the fitting portion, which fit into the S-shaped fitting groove, or (B) The semi-cylindrical member A consists of a member having an S-shaped fitting groove A formed on one outer surface of the fitting portion and an inverted S-shaped fitting groove A formed on the other inner surface, The semi-cylindrical member B is made up of a member having an inverted S-shaped fitting groove B formed on one inner surface of the fitting portion that fits with the S-shaped fitting groove A, and an S-shaped fitting groove B formed on the other outer surface that fits with the inverted S-shaped fitting groove A. A crystal growth vessel as described in configuration 3.

[0022] [Composition 5] The cylindrical member is a crystal growth container according to any one of configurations 1 to 4, wherein the thickness of the coating is 20 μm or more.

[0023] [Composition 6] The cylindrical member is a crystal growth container according to any one of configurations 1 to 5, wherein the height of the base material is 70 mm or more and 150 mm or less.

[0024] [Composition 7] The internal dimensions of the graphite crucible are within ±5.0 mm of the internal dimensions of the cylindrical member. The external dimensions of the graphite crucible are the internal dimensions of the graphite crucible + 20 mm or more + 40 mm or less. A crystal growth vessel described in any one of configurations 1 through 6.

[0025] [Structure 8] A crystal growth vessel according to any one of configurations 1 to 7, further comprising a cylindrical graphite guide arranged on the inner surface of the cylindrical member.

[0026] [Composition 9] A method for producing a SiC single crystal, comprising the step of growing a SiC single crystal on the surface of a seed crystal using a crystal growth vessel described in any one of items 1 to 8 of the configuration.

[0027] [Configuration 10] A cylindrical member having the following configuration. (1) The cylindrical member is used to surround the space between the graphite crucible holding the SiC raw material and the base holding the seed crystal when growing a SiC single crystal on the surface of a seed crystal using a sublimation method which involves heating and sublimating the SiC raw material using high-frequency induction heating. (2) The cylindrical member is A cylindrical base material made of graphite or a high melting point metal, A coating made of a high-melting-point metal carbide formed on the inner and / or outer surfaces of the substrate, Equipped with, The internal dimensions are 150mm or more. however, The aforementioned "high melting point metal" refers to a metal with a melting point of 2000°C or higher. The term "high melting point metal carbide" refers to a carbide containing at least one of the aforementioned high melting point metals.

[0028] Hereinafter, one embodiment of the present invention will be described in detail. [1. Cylindrical member] The cylindrical member according to the present invention is A cylindrical base material made of graphite or a high melting point metal, A coating made of a high-melting-point metal carbide formed on the inner and / or outer surfaces of the substrate, It is equipped with.

[0029] [1.1. Purpose] The cylindrical member according to the present invention is used to surround the space between a graphite crucible holding the SiC raw material and a base holding the seed crystal when growing a SiC single crystal on the surface of a seed crystal using a sublimation method that uses high-frequency induction heating to heat and sublimate the SiC raw material. The cylindrical member has the function of acting as a partition separating the SiC single crystal growth space from the external space and the function of defining the outer shape of the growing SiC single crystal. When the cylindrical member is placed so as to surround the seed crystal, sublimation gas is more easily retained inside, improving the growth rate of the single crystal and the raw material utilization efficiency (the ratio of the mass of the grown crystal to the mass of the SiC raw material).

[0030] Conventionally, isotropic graphite was commonly used for cylindrical members in this type of application. However, because sublimation gas is highly corrosive, cylindrical members made of isotropic graphite are significantly worn out after a single use and cannot be reused. In contrast, the cylindrical member according to the present invention has high corrosion resistance to sublimation gas and can withstand repeated use. Furthermore, molded graphite bodies, such as isotropic graphite, generally have a porosity of about 10-20%. Therefore, when a cylindrical member is manufactured using a molded graphite body, the thinner the cylindrical member, the more likely sublimation gas is to leak. In contrast, the cylindrical member according to the present invention has a coating formed on its inner and / or outer surface, so it has excellent sublimation gas retention regardless of the material and thickness of the base material.

[0031] [1.2. Internal dimensions] The "internal dimension" of a cylindrical member refers to the diameter of the largest inscribed circle that circulates within the inner surface of the cylindrical member. Since the thickness of the base material is significantly greater than the thickness of the coating, the internal dimension of the cylindrical member can be considered identical to the internal dimension of the base material. In the present invention, the inner dimension of the cylindrical member is 150 mm or more. Preferably, the inner dimension is 160 mm or more, or 170 mm or more.

[0032] Generally, when growing single crystals using the sublimation method, increasing the diameter of the single crystal requires a correspondingly larger diameter of the raw material crucible. However, as the diameter of the raw material crucible increases, it becomes more difficult to heat the crucible uniformly. As a result, the crystal growth rate and raw material utilization efficiency may decrease.

[0033] In contrast, using the cylindrical member according to the present invention, SiC single crystals with a diameter of 150 mm or more can be grown without significantly reducing the crystal growth rate or raw material utilization efficiency. By further optimizing the internal dimensions of the cylindrical member and the manufacturing conditions, even SiC single crystals with a diameter of 300 mm can be grown.

[0034] [1.3. Base material] [1.3.1. Materials] The base material consists of graphite or a high-melting-point metal. In this invention, the type of graphite constituting the base material is not particularly limited. Examples of graphite include isotropic graphite (also called "CIP-molded graphite"), extruded graphite, and molded graphite. In this invention, "high melting point metal" refers to a metal with a melting point of 2000°C or higher. Examples of high melting point metals include Ta, W, Re, Mo, Nb, Ir, and Hf. When the base material is made of a high melting point metal, the base material may be made of any one of these high melting point metals, or it may be an alloy containing two or more of them. Among these, isotropic graphite is preferred as the base material. Isotropic graphite is suitable as a base material because it has high strength, excellent heat resistance, and is easy to process.

[0035] [1.3.2. Shape] The cylindrical member is intended to isolate the SiC single crystal growth space from the external space and to secure the SiC single crystal growth space around the seed crystal. Therefore, the substrate is cylindrical. The substrate may be cylindrical, elliptical, or polygonal (square, hexagonal, octagonal, etc.). Among these, a cylindrical base material is preferred. Compared to elliptical or polygonal cylinders, cylinders allow for more uniform heating and are easier to process, making them a suitable shape for the base material.

[0036] [1.3.3. Thick meat] In the present invention, the thickness of the base material is not particularly limited, and an optimal value can be selected depending on the purpose. Generally, if the thickness of the base material is too thin, the strength of the cylindrical member may be insufficient, and distortion may occur. Therefore, the thickness of the base material is preferably 1.0 mm or more. More preferably, the thickness is 2.0 mm or more, or 3.0 mm or more.

[0037] On the other hand, a heating coil is positioned on the outside of the cylindrical member. Therefore, if the thickness of the base material is made thicker than necessary, the surface of the cylindrical member will come closer to the heating coil, and the cylindrical member may be excessively heated by eddy currents. If the temperature of the cylindrical member becomes excessively high, it becomes difficult to form a large temperature difference between the raw material crucible and the seed crystal, which may reduce the crystal growth rate. For this reason, the thickness of the base material is preferably 8.0 mm or less. More preferably, the thickness is 7.0 mm or less, or 6.0 mm or less.

[0038] [1.3.4. Height] The height of the substrate is not particularly limited, and an optimal value can be selected depending on the purpose. Generally, if the height of the substrate is too low, it becomes difficult to manufacture single crystals with a high growth height. Therefore, a substrate height of 70 mm or more is preferable. More preferably, the height is 80 mm or more, or 90 mm or more. On the other hand, because there is a limit to the amount of sublimation material that can be filled into the graphite crucible, there is also a limit to the achievable growth height. Therefore, there is no practical benefit in making the substrate height higher than necessary. Accordingly, the substrate height is preferably 150 mm or less. More preferably, the height is 140 mm or less, or 130 mm or less.

[0039] [1.4. Coating] [1.4.1. Materials] A coating made of high-melting-point metal carbide is formed on the inner and / or outer surfaces of the substrate. The coating formed on the inner surface of the substrate has the function of protecting the substrate from corrosive gases. Furthermore, if the substrate is made of a porous material, the coatings formed on the inner and outer surfaces of the substrate also have the function of retaining sublimation gases within the growth space, respectively. Therefore, when a coating is formed only on the outer surface of the substrate, the crystal growth rate may be improved compared to when an uncoated substrate is used. Furthermore, when a coating is formed only on the inner surface of the substrate, corrosion of the substrate may be suppressed and the crystal growth rate may be improved compared to when an uncoated substrate is used. Moreover, when a coating is formed on both the inner and outer surfaces of the substrate, the crystal growth rate may be further improved compared to when a coating is formed only on the inner surface of the substrate.

[0040] In the present invention, the coating consists of a high-melting-point metal carbide. "High-melting-point metal carbide" means a carbide containing at least one of the aforementioned high-melting-point metals. Examples of high-melting-point metal carbides include TaC, WC, ReC, Mo2C, NbC, IrC, and HfC. The coating may contain one of these high-melting-point metal carbides, or it may contain two or more.

[0041] In particular, TaC is preferred as the high-melting-point metal carbide. This is because TaC has high corrosion resistance, high high-temperature stability, and low emissivity (0.2-0.3). The coating may contain only TaC as the high-melting-point metal carbide, or it may contain TaC in addition to other high-melting-point metal carbides. Furthermore, the coating may contain other components in addition to the high-melting-point metal carbide (for example, residue from sintering aids).

[0042] [1.4.2. Relative Density] "Relative density" refers to the ratio of the apparent density of a coating to its theoretical density. The coating functions as a protective material for the substrate. In order to suppress substrate wear in the SiC single crystal growth atmosphere, a higher relative density of the coating is preferable. Specifically, a relative density of 95% or higher is preferable. More preferably, the relative density is 97% or higher, or 99% or higher.

[0043] Dense coatings made of high-melting-point metal carbides such as TaC, NbC, HfC, ZrC, WC, and Mo2C exhibit excellent gas impermeability and corrosion resistance. Therefore, coating the inner surface of a substrate with a dense film made of high-melting-point metal carbides can suppress the wear and tear of the substrate.

[0044] [1.4.3. Thickness] The thickness of the coating is not particularly limited, and the optimal thickness can be selected according to the purpose. Generally, if the coating is too thin, it becomes difficult to suppress the wear of the substrate and / or the leakage of sublimation gas. Therefore, a coating thickness of 20 μm or more is preferable. More preferably, the thickness is 30 μm or more, 40 μm or more, or 50 μm or more. On the other hand, if the coating becomes too thick, cracks may develop in the coating or the coating may peel off. Therefore, the thickness of the coating is preferably 200 μm or less. More preferably, the thickness is 150 μm or less, or 100 μm or less.

[0045] [1.5. Interlocking two-part component] [1.5.1. Definition] The cylindrical member may be made of a single, integrated member (a cylindrical member without seams), or it may be made of a two-part, interlocking member. Here, "interlocking two-part member" refers to a member formed by interlocking two semi-cylindrical members, A and B, which have a shape obtained by dividing a cylinder in the axial direction, through the dividing surface.

[0046] The thermal expansion coefficient of a SiC single crystal is smaller than that of the materials that make up the coating and substrate. Therefore, when a SiC single crystal grows without gaps inside a cylindrical member and then cools to room temperature, the SiC single crystal expands relative to the cylindrical member. As a result, if the cylindrical member is made from a single piece of material, it may crack during the cooling process. In contrast, if the cylindrical member is made into a two-part interlocking member, even if the SiC single crystal expands relative to the cylindrical member during cooling, the interlocking portion disengages, relieving the tensile stress. As a result, damage to the cylindrical member can be avoided.

[0047] The structure of the two-part member is not particularly limited, as long as the structure allows the interlocking portion to easily detach when the SiC single crystal expands relative to the cylindrical member. Specific examples of two-part member structures include the following:

[0048] [1.5.2. Specific Example 1] Figure 1 shows an axial cross-sectional view of a first specific example of a two-part interlocking member. In Figure 1, the cylindrical member 30 comprises a semi-cylindrical member A32 and a semi-cylindrical member B34. Both the semi-cylindrical member A32 and the semi-cylindrical member B34 have a shape obtained by dividing a cylinder into two parts in the axial direction, and when viewed from the axial direction, their inner and outer shapes are semi-circular.

[0049] The semi-cylindrical member A32 consists of a member having S-shaped fitting grooves 32a and 32b formed on both outer surfaces of the fitting portion. The semi-cylindrical member B34 consists of a member having inverted S-shaped fitting grooves 34a and 34b formed on both inner surfaces of the fitting portion, which fit with the S-shaped fitting grooves 32a and 32b.

[0050] Therefore, when the semi-cylindrical members A32 and B34 are fitted together via the dividing surface such that the S-shaped fitting groove 32a and the inverted S-shaped fitting groove 34a engage, and the S-shaped fitting groove 32b and the inverted S-shaped fitting groove 34b engage, a cylindrical member 30 with a circular inner and outer surface shape is obtained. The cylindrical member 30 shown in Figure 1 is formed by fitting together a male (semi-cylindrical member A32) and a female (semi-cylindrical member B34), making it difficult for the fitting parts to come apart during handling. In addition, because the fitting parts are curved in an S-shape, sublimation gas is less likely to leak from the fitting parts to the outside of the cylindrical member 30. In particular, increasing the curvature of the S-shaped and inverted S-shaped grooves makes it less likely for the mating parts to come loose even when external forces are applied during handling. Also, thermal stress is generated between the SiC single crystal and the cylindrical member 30 due to the difference in thermal contraction during the cooling process after growth, but if the curvature of the groove is increased, the mating parts become more likely to come loose due to the thermal stress generated during cooling alone.

[0051] [1.5.3. Specific Example 2] Figure 2 shows an axial cross-sectional view of a second specific example of a two-part interlocking member. In Figure 2, the cylindrical member 30 comprises a semi-cylindrical member A36 and a semi-cylindrical member B38. Both the semi-cylindrical member A36 and the semi-cylindrical member B38 have a shape obtained by dividing a cylinder into two parts in the axial direction, and when viewed from the axial direction, their inner and outer shapes are semi-circular.

[0052] The semi-cylindrical member A36 consists of a member having an S-shaped fitting groove A36a formed on one outer surface of the fitting portion and an inverted S-shaped fitting groove A36b formed on the other inner surface. The semi-cylindrical member B38 consists of a member having an inverted S-shaped fitting groove B38a formed on one inner surface of the fitting portion which fits with the S-shaped fitting groove A36a, and an S-shaped fitting groove B38b formed on the other outer surface which fits with the inverted S-shaped fitting groove A36b.

[0053] Therefore, when the semi-cylindrical members A36 and B38 are fitted together via the dividing surface such that the S-shaped fitting groove A36a and the inverted S-shaped fitting groove B38a engage, and the inverted S-shaped fitting groove A36b and the S-shaped fitting groove B38b engage, a cylindrical member 30 with a circular inner and outer surface shape is obtained. Unlike the cylindrical member 30 shown in Figure 1, the cylindrical member 30 shown in Figure 2 does not require stress to be applied during fitting, thus simplifying the fitting process. Furthermore, because the fitting portion is curved in an S-shape, sublimation gas is less likely to leak from the fitting portion to the outside of the cylindrical member 30.

[0054] [2. Single crystal manufacturing equipment] Figure 3 shows a schematic diagram of a single crystal manufacturing apparatus equipped with a crystal growth container according to the present invention. In Figure 3, the single crystal manufacturing apparatus 10 comprises a crystal growth container 20, a heat-insulating material 44, a cylindrical heat-uniform heat-insulating material 46, and a plate-shaped heat-uniform heat-insulating material 48.

[0055] [2.1. Crystal Growth Vessel] The crystal growth vessel 20 is A graphite crucible 24 for holding the SiC raw material 22 which is heated and sublimated using high-frequency induction heating, A base 28 for holding a seed crystal 26 for growing a SiC single crystal, A cylindrical member 30 is positioned between the graphite crucible 24 and the base 28. It is equipped with. The crystal growth vessel 20 is (a) Lower auxiliary heater 40 located at the bottom of graphite crucible 24, and / or (b) A cylindrical graphite guide 42 placed on the inner surface of the cylindrical member 30 It would be good to have even more of these features.

[0056] [2.1.1. Graphite Crucible] [A. Shape] The graphite crucible 24 is both a container for holding the SiC raw material 22 and a heating element that generates heat through high-frequency induction heating. The shape of the graphite crucible 24 is not particularly limited, as long as it is capable of efficiently sublimating the SiC raw material 22. Examples of graphite crucible shapes include bottomed cylinders, bottomed elliptical cylinders, and bottomed polygonal cylinders.

[0057] [B. Internal dimensions, external dimensions] The "internal dimensions" of graphite crucible 24 refer to the diameter of the largest inscribed circle that is inscribed on the inner surface of graphite crucible 24. The "external dimensions" of graphite crucible 24 refer to the diameter of the smallest circumscribed circle that circumscribes the outer surface of graphite crucible 24. It is preferable to select the optimal internal and external dimensions of the graphite crucible 24 according to the purpose.

[0058] If the internal dimensions of the graphite crucible 24 become too small, it may become difficult to grow large-diameter SiC single crystals. Therefore, the internal dimensions of the graphite crucible 24 are preferably at least the internal dimensions of the cylindrical member 30 minus 5.0 cm. On the other hand, making the inner dimensions of the graphite crucible 24 larger than necessary does not make a difference in effectiveness and is not practical. Therefore, it is preferable that the inner dimensions of the graphite crucible 24 be the inner dimensions of the cylindrical member 30 + 5 cm or less.

[0059] Furthermore, if the inner dimensions of the graphite crucible 24 are larger than the outer dimensions of the cylindrical member 30, it is preferable to insert an annular spacer (not shown) between the graphite crucible 24 and the cylindrical member 30 to prevent the cylindrical member 30 from falling.

[0060] If the outer dimensions of the graphite crucible 24 are too small compared to its inner dimensions, the wall thickness of the graphite crucible 24 will become excessively thin, and holes may form in the outer wall of the graphite crucible 24 due to corrosion during single crystal growth. Furthermore, a certain thickness is necessary for efficient heating by high-frequency heating. Therefore, the outer dimensions of the graphite crucible 24 are preferably the inner dimensions of the graphite crucible 24 + 20 mm or more. On the other hand, making the external dimensions of the graphite crucible 24 larger than necessary does not make a difference in effectiveness and is not practically beneficial. Therefore, it is preferable that the external dimensions of the graphite crucible 24 be no more than the internal dimensions of the graphite crucible 24 + 40 mm.

[0061] [2.1.2. Pedestal] The base 28 is for holding a seed crystal 26 for growing a SiC single crystal. The shape of the base 28 is not particularly limited, as long as it is capable of holding the seed crystal 26. In Figure 1, the base 28 is dish-shaped, and the seed crystal 26 is bonded to its bottom surface. The upper end of the base 28 is provided with a flange that protrudes outward. The base 28 is installed on the cylindrical member 30 by placing the flange on the upper end of the cylindrical member 30. The material of the base 28 is not particularly limited, and the most suitable material can be selected depending on the purpose. Graphite is typically used for the base 28.

[0062] [2.1.3. Cylindrical Members] The cylindrical member 30 is positioned between the graphite crucible 24 and the base 28. As described above, the cylindrical member 30 functions as a partition separating the SiC single crystal growth space from the external space, and also functions to define the outer shape of the growing SiC single crystal. Therefore, by positioning the cylindrical member 30 so as to surround the seed crystal 26, sublimation gas is more easily retained inside, improving the growth rate of the single crystal and the efficiency of raw material utilization. Further explanation of the cylindrical member 30 is omitted as it is described above.

[0063] [2.1.4. Lower auxiliary heater] The lower auxiliary heater 40 is a heating element that generates heat by high-frequency induction heating and is made of graphite. The lower auxiliary heater 40 is cylindrical and is located at the bottom of the graphite crucible 24. The lower auxiliary heater 40 is not always necessary. However, without the lower auxiliary heater 40, the temperature at the bottom of the graphite crucible 24 may decrease, reducing the sublimation efficiency. In contrast, placing the lower auxiliary heater 40 at the bottom of the graphite crucible 24 suppresses the temperature drop at the bottom of the graphite crucible 24, improving the sublimation efficiency.

[0064] [2.1.5. Graphite Guide] The graphite guide 42 is positioned on the inner surface of the cylindrical member 30. The graphite guide 42 is cylindrical and has external dimensions that allow it to be inserted into the cylindrical member 30 without any gaps. The upper end of the graphite guide 42 is provided with a flange that protrudes outward. The graphite guide 42 is installed on the cylindrical member 30 by resting the flange on the upper end of the cylindrical member 30.

[0065] The graphite guide 42 is not always necessary. However, in the absence of the graphite guide 42, if the sublimation conditions are inappropriate, the atomic ratio of Si to C in the sublimation gas may not be approximately 1:1, and the sublimation gas may become Si-rich. When the composition of the sublimation gas becomes Si-rich, Si droplets may form during the growth process of the SiC single crystal. In contrast, by placing the graphite guide 42 on the inner surface of the cylindrical member 30, an appropriate amount of C is supplied to the sublimation gas, bringing the atomic ratio of Si to C in the sublimation gas closer to approximately 1:1.

[0066] [2.2. Thermal insulation materials] [2.2.1. Materials] The heat-insulating material 44 is an insulating material for keeping the crystal growth container 20 warm, and is arranged to cover the top, sides, and bottom of the crystal growth container 20. The heat-insulating material 44 is provided with an upper temperature-measuring hole 44a on its top surface and a lower temperature-measuring hole 44b on its bottom surface. The upper temperature-measuring hole 44a is for measuring the temperature of the underside of the base 28 during single crystal growth. The lower temperature-measuring hole 44b is for measuring the temperature of the bottom of the crystal growth container 20 during single crystal growth. In the example shown in Figure 1, a plate-shaped heat-uniform insulation material 48 is placed at the lower end of the auxiliary lower heater 40, so the lower temperature-measuring hole 44b is used to measure the temperature of the underside of the plate-shaped heat-uniform insulation material 48.

[0067] The material of the heat-insulating material 44 is not particularly limited, as long as it is capable of keeping the crystal growth container 20 warm. Examples of materials for the heat-insulating material 44 include: (a) Carbon fiber felt, (b) Molded thermal insulation material obtained by impregnating a carbon fiber substrate with a resin with a high carbonization rate, molding it into the desired shape, and then curing, carbonizing, and graphitizing the molded body. These are some examples.

[0068] [2.2.2. Shape and Dimensions] Since the heat-insulating material 44 needs to cover almost the entire circumference of the crystal growth container 20, the heat-insulating material 44 is not a single piece but is usually divided into multiple parts. In order to cover almost the entire circumference of the crystal growth container 20, it is preferable that the heat-insulating material 44 is divided into upper and lower plate-shaped members and one or more cylindrical members placed between the upper and lower plate-shaped members. Furthermore, in order to improve the thermal insulation efficiency of the heat-retaining insulation material 44, it is preferable that there is no gap between the heat-retaining insulation material 44 and the crystal growth container 20 or the cylindrical heat-uniform insulation material 46. The thickness of each part of the heat-insulating material 44 is not particularly limited, as long as it is sufficient to keep the crystal growth container 20 warm.

[0069] [2.3. Cylindrical heat-distributing insulation material] [2.3.1. Materials] The cylindrical heat-uniform insulation material 46 is an insulating material used to equalize the temperature of the graphite crucible 24. In the example shown in Figure 3, it is inserted between the outer surface of the graphite crucible 24 and the lower auxiliary heater 40 and the inner surface of the heat-insulating insulation material 44. The larger the diameter of the graphite crucible 24, the more difficult it becomes to equalize the temperature of the graphite crucible 24. In contrast, by inserting the cylindrical heat-uniform insulation material 46 at least between the graphite crucible 24 and the heat-insulating insulation material 44, the temperature of the graphite crucible 24 can be made more uniform even when the diameter of the graphite crucible 24 is large.

[0070] The material of the cylindrical heat-uniform insulation material 46 is not particularly limited, as long as it is capable of making the temperature of the graphite crucible 24 uniform. The material of the cylindrical heat-uniform insulation material 46 is preferably a graphite sheet or a laminate thereof. A graphite sheet or a laminate thereof has a lower thermal conductivity in the thickness direction compared to its thermal conductivity in the in-plane direction, so heat dissipation from the graphite crucible 24 (especially from the upper or lower end of the graphite crucible 24) is suppressed, and the temperature of the graphite crucible 24 can be made more uniform.

[0071] Here, "graphite sheet" refers to a sheet made by roll-forming flexible, expandable natural graphite, or a molded sheet of artificial graphite. For example, graphite sheets include: (a) Manufactured by Toyo Tanso, PERMA-FOIL (registered trademark), (b) Made by Japan Carbon, Nikafilm (registered trademark), (c) Panasonic Corporation, Graphite™ (d) GRAFOIL® or eGRAF manufactured by Graftech. These are some examples. Furthermore, a "laminated graphite sheet" refers to a structure in which multiple graphite sheets are layered together and bonded together with a graphite-based adhesive.

[0072] The material of the cylindrical heat-distributing insulation material 46 is, in particular, The thermal conductivity in the thickness direction at room temperature is 30 W / (m·K) or less. Thermal conductivity in the in-plane direction at room temperature is 100 W / (m·K) or higher. This is preferable. Graphite sheets or laminates thereof usually satisfy this condition.

[0073] [2.3.2. Shape and Dimensions] In order to improve the insulation efficiency of the cylindrical heat-uniform insulation material 46, it is preferable that the shape of the cylindrical heat-uniform insulation material 46 is such that it can be inserted between the graphite crucible 24 and the heat-insulating insulation material 44 without creating gaps between the cylindrical heat-uniform insulation material 46 and the graphite crucible 24, and between the cylindrical heat-uniform insulation material 46 and the heat-insulating insulation material 44.

[0074] For example, if the graphite crucible 24 is a bottomed cylindrical shape, the cylindrical heat-sensing insulation material 46 is preferably cylindrical in shape, with an inner diameter slightly larger than the outer diameter of the graphite crucible 24 and an outer diameter slightly smaller than the inner diameter of the heat-insulating insulation material 46. If a gap occurs between the cylindrical heat-uniform insulation material 46 and an adjacent member, the gap may be filled with an insulating material (for example, graphite fiber felt).

[0075] The thickness of the cylindrical heat-uniform insulation material 46 affects its thermal insulation performance. If the thickness of the cylindrical heat-uniform insulation material 46 is too thin, the temperature of the graphite crucible 24 may become uneven. As a result, when the diameter of the graphite crucible 24 is large, the growth rate of the single crystal may decrease. Therefore, the thickness of the cylindrical heat-uniform insulation material 46 is preferably 1 mm or more. More preferably, the thickness is 3 mm or more, 5 mm or more, or 10 mm or more.

[0076] On the other hand, making the thickness of the tubular heat-uniform insulation material 46 thicker than necessary does not make a difference in effectiveness and is not beneficial. Therefore, the thickness of the tubular heat-uniform insulation material 46 is preferably 50 mm or less. More preferably, the thickness is 40 mm or less, 30 mm or less, or 20 mm or less.

[0077] [2.4. Plate-shaped heat-distributing insulation material] [2.4.1. Materials] The plate-shaped heat-uniform insulation material 48 is an insulating material for suppressing heat dissipation from the bottom of the crystal growth container 20, and is inserted between the outer bottom surface of the crystal growth container 20 and the inner bottom surface of the heat-retaining insulation material 44. The plate-shaped heat-distributing insulation material 48 is not necessarily required. However, inserting the plate-shaped heat-distributing insulation material 48 between the crystal growth container 20 and the heat-retaining insulation material 44 can further suppress heat dissipation from the bottom of the crystal growth container 20.

[0078] The material of the plate-shaped heat-uniform insulation material 48 is not particularly limited, as long as it can suppress heat dissipation from the bottom of the crystal growing container 20. The material of the plate-shaped heat-uniform insulation material 48 is preferably a graphite sheet or a laminate thereof. Because the thermal conductivity in the thickness direction is smaller than the thermal conductivity in the in-plane direction of a graphite sheet or laminate thereof, heat dissipation from the bottom of the crystal growth container is suppressed, and the temperature of the graphite crucible 24 can be made more uniform. Details of the graphite sheet and laminate thereof are as described above, so a further explanation is omitted.

[0079] [2.4.2. Shape and Dimensions] The shape of the plate-shaped heat-distributing insulation material 48 is not particularly limited, as long as it is a shape that can suppress heat dissipation from the crystal growing container 20. Preferably, the plate-shaped heat-distributing insulation material 48 has the same planar shape as the axial cross-sectional shape of the crystal growth container 20.

[0080] The thickness of the plate-shaped heat-distributing insulation material 48 affects its heat-insulating performance. If the thickness of the plate-shaped heat-distributing insulation material 48 is too thin, the insulation of the lower part of the crystal growth container 20 may become insufficient. As a result, when the diameter of the graphite crucible 24 is large, the growth rate of the single crystal may decrease. Therefore, the thickness of the plate-shaped heat-distributing insulation material 48 is preferably 1 mm or more. More preferably, the thickness is 3 mm or more, 5 mm or more, or 10 mm or more.

[0081] On the other hand, making the thickness of the plate-shaped heat-uniform insulation material 48 thicker than necessary does not make a difference in effectiveness and is not beneficial. Therefore, the thickness of the plate-shaped heat-uniform insulation material 48 is preferably 50 mm or less. More preferably, the thickness is 40 mm or less, 30 mm or less, or 20 mm or less.

[0082] [3. Method for manufacturing SiC single crystals] The method for producing a SiC single crystal according to the present invention comprises the step of growing a SiC single crystal on the surface of a seed crystal using a crystal growth vessel according to the present invention. A graphite crucible 24 is filled with SiC raw material 22, and a seed crystal 26 is held on a base 28. When the SiC raw material 22 is heated in this state, a SiC single crystal grows on the surface of the seed crystal 26. In this case, by appropriately controlling the temperature difference between the SiC raw material 22 and the seed crystal 26, a large-diameter SiC single crystal with a high growth height can be grown in a short time.

[0083] [4. Effect] [4.1. Substrate Thickness and Growth Rate] When growing SiC single crystals, placing a large-diameter cylindrical member with a high-melting-point metal carbide coating on its inner and / or outer surfaces between the raw material crucible and the base allows for the growth of large-diameter SiC single crystals with fewer defects. In this case, optimizing the wall thickness of the cylindrical member allows for the rapid growth of high-growing SiC single crystals. This is thought to be because optimizing the wall thickness of the cylindrical member suppresses excessive heat generation in the cylindrical member, creating an appropriate temperature gradient between the SiC raw material and the seed crystal.

[0084] [4.2. Advantages of interlocking two-part components] Cylindrical members with a high-melting-point metal carbide coating on their inner surface show almost no damage even after prolonged sublimation-based bulk SiC single crystal growth. Therefore, such cylindrical members can be used multiple times, leading to a significant reduction in material costs. However, in order to suppress the peeling of the coating, it is necessary to bring the thermal expansion coefficient of the substrate closer to that of the coating. Thermal expansion coefficient of the substrate and coating (in the case of TaC, approximately 6 × 10) -6 K -1 ) is the thermal expansion coefficient of SiC (approximately 4 × 10⁻⁶). -6 K -1 Because it is larger than the SiC single crystal, the cylindrical member shrinks more significantly during the cooling process after crystal growth. As a result, the tensile stress generated in the cylindrical member can cause it to crack, making repeated use impossible.

[0085] In contrast, by using a two-part interlocking tubular member, even if tensile stress occurs in the tubular member during cooling, only the interlocking part will come apart, preventing cracking of the tubular member. As a result, both high airtightness and crack prevention of the tubular member can be achieved, enabling repeated long-length growth at low cost. [Examples]

[0086] (Example 1, Comparative Example 1) [1. Fabrication of a single crystal manufacturing apparatus] SiC single crystals were grown using the single crystal manufacturing apparatus 10 shown in Figure 3. Details of each part of the single crystal manufacturing apparatus 10 are as follows.

[0087] [1.1. Crucible, base, lower auxiliary heater, graphite guide, cylindrical member] For the graphite crucible 24, an isotropic graphite crucible with an outer diameter of 190 mm, an inner diameter of 160 mm, a total height of 178 mm, and an effective depth of 165 mm was used. Base 28 uses an isotropic graphite base with an outer diameter of 170 mm. The lower auxiliary heater 40 uses an isotropic graphite heater with an outer diameter of 190 mm, an inner diameter of 160 mm, and a total height of 40 mm. The graphite guide 42 uses an isotropic graphite guide with an outer diameter of 158 mm, an inner diameter of 151 mm, and a total height of 90 mm.

[0088] The cylindrical member 30 includes, (a) A cylindrical member (Example 1) having a dense TaC coating with a thickness of 100 μm formed on the inner and outer surfaces of the substrate, or (b) A cylindrical member consisting only of a base material (Comparative Example 1) I used it. An isotropic graphite substrate with an outer diameter of 170 mm, an inner diameter of 160 mm, and a total height of 90 mm was used as the base material.

[0089] [1.2. Thermal insulation materials] The thermal insulation material 44 has a bulk density of 0.16 g / cm³. 3 The primary material used was a molded insulation material based on graphite fiber felt. The outer diameter of the thermal insulation material 44 was 270 mm, and the total height was 450 mm. The inner diameter of the section where the graphite crucible 24 is inserted was 210 mm, the inner diameter of the section where the cylindrical member 30 is inserted was 190 mm, and the total height of the internal space was 320 mm. An upper temperature sensing hole 44a with a diameter of 30 mm was formed in the upper center of the thermal insulation material 44. Furthermore, a lower temperature sensing hole 44b with a diameter of 12 mm was formed in the lower center of the thermal insulation material 44.

[0090] [1.3. Seed crystal, raw material for sublimation] A 4H-SiC(0001) 3.5° off-center substrate with a diameter of 150 mm and a thickness of 350 μm was used as the seed crystal 26. The SiC substrate was bonded and fixed to the base 28 so that the C-plane side of the SiC substrate would be the growth surface. For the SiC raw material 22, SiC powder with an average particle size of 500 μm was used. 4.19 kg of this SiC powder was loaded into graphite crucible 24. The raw material height was approximately 124 mm. This corresponds to a powder packing density of approximately 53%.

[0091] [1.4. Cylindrical heat-distributing insulation material, plate-shaped heat-distributing insulation material] The graphite sheet used was PERMA-FOIL® (registered trademark) manufactured by Toyo Tanso (product code: PH-50UHP, 500 μm thick, or product code: PH-100UHP, 1.0 mm thick). The thermal conductivity of PERMA-FOIL® in the thickness direction is ~5 W / (m·K) (@room temperature), and the thermal conductivity in the in-plane direction is ~200 W / (m·K) (@room temperature). In the computer simulations described later, the thermal conductivity of the graphite sheet at temperatures exceeding 2000°C was assumed to decrease to one-third of that at room temperature (thermal conductivity in the thickness direction was 2 W / (m·K), and thermal conductivity in the in-plane direction was 70 W / (m·K)).

[0092] By bonding and molding the above graphite sheets, a cylindrical heat-uniform insulation material 46 and a plate-shaped heat-uniform insulation material 48 were produced. The cylindrical heat-uniform insulation material 44 was fabricated by winding a 500 μm thick graphite sheet 15 times and bonding and fixing the layers together with a graphite-based adhesive. The resulting cylindrical heat-uniform insulation material 44 had an outer diameter of 210 mm, an inner diameter of 190 mm, and a total height of 220 mm. The plate-shaped heat-distributing insulation material 48 was fabricated by laminating 10 sheets of 1.0 mm thick graphite and bonding the layers together with a graphite-based adhesive. The resulting plate-shaped heat-distributing insulation material 48 had an outer diameter of 190 mm and a total height of 10 mm.

[0093] [2. Manufacturing of SiC single crystals by sublimation method] SiC single crystals were produced using a single crystal manufacturing apparatus 10. The crystal growth pressure was 200 Pa, the atmosphere was Ar: 95 vol% + N2: 5 vol, and the growth time was 144 h. Regarding the growth temperature, the high-frequency power and coil position were adjusted so that the temperature on the underside of the base 28, measured with a radiation thermometer through the upper temperature sensing hole 44a, was ~2200°C, and the bottom temperature of the plate-shaped heat-uniform insulation material 48, measured with a radiation thermometer through the lower temperature sensing hole 44b, was ~2200°C. Continuous growth was carried out for 144 hours while adjusting the temperature so that the bottom temperature of the plate-shaped heat-uniform insulation material 48 remained constant at ~2200°C.

[0094] [3. Test Methods and Results] After growing SiC single crystals under the above conditions, the growth height of the single crystals, the average growth rate of the single crystals, the raw material yield, and the leakage amount were measured. Here, "average growth rate" refers to the value obtained by dividing the growth height of the single crystal by the growth time. "Raw material yield" refers to the ratio of the mass of single crystals grown on the surface of the seed crystal 26 to the mass of SiC raw material 22 charged into the graphite crucible 24. "Leakage amount" refers to the decrease in the total mass of the crystal growth container 20 before and after growth. "Total mass of the crystal growth container 20" refers to the total mass of the graphite crucible 24, SiC raw material 22, cylindrical member 30, graphite guide 42, seed crystal 26, and base 28. Table 1 shows the results. From Table 1, the following can be seen:

[0095] [Table 1]

[0096] (1) In Comparative Example 1, the single crystal growth height was 42.8 mm, the average growth rate was 297 μm / h, the raw material yield was 58.0%, and the leakage amount was 958 g. The cylindrical member after growth was confirmed to be significantly damaged by visual inspection. The mass defect of the cylindrical member was approximately 5%. (2) In Example 1, the single crystal growth height was 58.3 mm and the average growth rate was 405 μm / h, which was approximately 1.4 times that of Comparative Example 1. The raw material yield was 79.0%, which was also approximately 1.4 times that of Example 1. Furthermore, the leakage amount was 102 g, which was significantly lower than that of Comparative Example 1. It was found that the reduction in leakage amount was the main factor in the improvement of raw material yield and, consequently, the improvement in growth height. This reduction in leakage amount is thought to be due to the prevention of damage to the substrate by the presence of a dense TaC coating (no mass defects), as well as the suppression of sublimation gas leakage due to high airtightness.

[0097] (Example 2) [1. Test Method] We performed computer simulations of the initial growth rate using a Virtual Reactor from STR Japan. In the configuration shown in Figure 3, we fixed the inner diameter of the cylindrical member 30 to 160 mm and the total height to 90 mm, and calculated the initial growth rate for seven cases in which the wall thickness of the base material was 1, 2, 3, 5, 7, 10, or 15 mm. We assumed that there was no gap between the cylindrical member 30 and the heat-insulating material 44. "Initial growth rate" refers to the value obtained by dividing the height after one hour from the start of growth by the growth time.

[0098] [2. Results] Figure 4 shows the relationship between the wall thickness of the tubular member's base material and the initial growth rate. From Figure 4, it can be seen that the initial growth rate improves as the wall thickness of the base material decreases. When the outer diameter of the cylindrical member 30 was the same as that of the graphite crucible 24 (i.e., when the wall thickness was 15 mm), the initial growth rate was 165 μm / h. On the other hand, when the wall thickness was 10 mm, the initial growth rate was approximately 1.5 times that of the 15 mm wall thickness. Furthermore, when the wall thickness was 8 mm or less, the initial growth rate was approximately 1.8 times or more that of the 15 mm wall thickness, confirming a significant improvement in growth rate.

[0099] Figure 4 shows that a substrate thickness of 10 mm has the effect of improving the initial growth rate, and is more preferably 8 mm or less. To ensure a more reliable effect of improving the initial growth rate, a substrate thickness of approximately 3 to 7 mm is considered even more preferable. However, if the thickness becomes too thin, the strength of the substrate may be insufficient or distortion may occur. Therefore, a thickness of 1 mm or more is preferable.

[0100] Although embodiments of the present invention have been described in detail above, the present invention is not limited in any way to the above embodiments, and various modifications are possible without departing from the spirit of the present invention. [Industrial applicability]

[0101] The crystal growth container and cylindrical member according to the present invention can be used in the production of SiC single crystals using the sublimation method. [Explanation of Symbols]

[0102] 20 Crystal growth vessel 22 SiC raw material 24 Graphite Crucibles 26 Seed Crystal 28 Pedestal 30 Cylindrical member

Claims

1. A crystal growth vessel having the following configuration. (1) The crystal growth vessel is A graphite crucible for holding SiC raw materials that are heated and sublimated using high-frequency induction heating, A base for holding a seed crystal for growing a SiC single crystal, A cylindrical member is placed between the graphite crucible and the base. It is equipped with. (2) The cylindrical member is A cylindrical base material made of graphite or a high melting point metal, A coating made of a high-melting-point metal carbide formed on the inner and / or outer surfaces of the substrate, Equipped with, The internal dimensions are 150 mm or more. however, The aforementioned "high melting point metal" refers to a metal with a melting point of 2000°C or higher. The term "high melting point metal carbide" refers to a carbide containing at least one of the aforementioned high melting point metals.

2. The crystal growth container according to claim 1, wherein the cylindrical member has a wall thickness of 1.0 mm or more and 8.0 mm or less.

3. The crystal growth vessel according to claim 1, wherein the cylindrical member comprises a two-part interlocking member formed by fitting together a semi-cylindrical member A and a semi-cylindrical member B, which have a shape obtained by dividing a cylinder in the axial direction, via a dividing surface.

4. The aforementioned cylindrical member is (A) The semi-cylindrical member A is made of a member having S-shaped fitting grooves formed on both outer surfaces of the fitting portion, The semi-cylindrical member B is made of a member having inverted S-shaped fitting grooves formed on both inner surfaces of the fitting portion, which fit into the S-shaped fitting groove, or (B) The semi-cylindrical member A is made up of a member having an S-shaped fitting groove A formed on one outer surface of the fitting portion and an inverted S-shaped fitting groove A formed on the other inner surface, The semi-cylindrical member B is made up of a member having an inverted S-shaped fitting groove B formed on one inner surface of the fitting portion that fits with the S-shaped fitting groove A, and an S-shaped fitting groove B formed on the other outer surface that fits with the inverted S-shaped fitting groove A. The crystal growth vessel according to claim 3.

5. The crystal growth container according to claim 1, wherein the cylindrical member has a coating thickness of 20 μm or more.

6. The crystal growth container according to claim 1, wherein the cylindrical member has a height of 70 mm or more and 150 mm or less.

7. The internal dimensions of the graphite crucible are within ±5.0 mm of the internal dimensions of the cylindrical member. The external dimensions of the graphite crucible are the internal dimensions of the graphite crucible plus 20 mm or more and the internal dimensions of the graphite crucible plus 40 mm or less. A crystal growth vessel according to claim 1.

8. The crystal growth vessel according to claim 1, further comprising a cylindrical graphite guide disposed on the inner surface of the cylindrical member.

9. A method for producing a SiC single crystal, comprising the step of growing a SiC single crystal on the surface of a seed crystal using a crystal growth vessel according to any one of claims 1 to 8.

10. A cylindrical member having the following configuration. (1) The cylindrical member is used to surround the space between the graphite crucible holding the SiC raw material and the base holding the seed crystal when growing a SiC single crystal on the surface of a seed crystal using a sublimation method which involves heating and sublimating the SiC raw material using high-frequency induction heating. (2) The cylindrical member is A cylindrical base material made of graphite or a high melting point metal, A coating made of a high-melting-point metal carbide formed on the inner and / or outer surfaces of the substrate, Equipped with, The internal dimensions are 150 mm or more. however, The aforementioned "high melting point metal" refers to a metal with a melting point of 2000°C or higher. The term "high melting point metal carbide" refers to a carbide containing at least one of the aforementioned high melting point metals.

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