Crystal growth device

Abstract

The present invention provides a crystal growth device which is capable of suppressing evaporation of a raw material melt. This crystal growth device is provided with a crucible that is capable of containing the raw material melt, while having a generally cylindrical shape. This crystal growth device is provided with a support shaft that is able to be inserted into the crucible from the above of the crucible, while being capable of rotating and vertically moving. A seed crystal is able to be mounted onto the lower end of the support shaft. The crystal growth device is provided with a specific member that is arranged in a direction that intersects with the support shaft. When a crystal is grown, the specific member is positioned below the upper end of the crucible.

Description

[Technical field]

[0001] This application claims priority based on Japanese Patent Application No. 2020-176924 filed on October 21, 2020, the entire contents of which are incorporated herein by reference. This specification discloses a technique related to a crystal growth apparatus. [Background technology]

[0002] As a method for producing SiC single crystals, a method (also known as liquid phase growth method) in which a crucible containing a raw material melt (solvent) heated to a high temperature is used to grow a SiC seed crystal in the liquid phase (see, for example, JP 2016-28015 A and JP 2016-059788 A). Summary of the Invention [Problem to be solved by the invention]

[0003] In liquid phase epitaxy, the raw material melt evaporates and adheres to the inner wall of the crucible. When the adhered raw material melt is cooled, the solid components solidify. This changes the amount and composition of the raw material melt, which can unintentionally change the liquid phase epitaxy environment, so it is necessary to suppress the evaporation of the raw material solution. [Means for solving the problem]

[0004] The crystal growth apparatus disclosed in this specification has a generally cylindrical shape and includes a crucible capable of containing a raw material melt. The crystal growth apparatus includes a support shaft that can be inserted into the crucible from above and can rotate and move up and down. A seed crystal can be attached to the lower end of the support shaft. The crystal growth apparatus includes a specified member that is disposed in a direction intersecting the support shaft. During crystal growth, the specified member is located below the upper end of the crucible.

[0005] During crystal growth, the specified member can function as a lid that covers the top of the crucible. This increases the airtightness of the inside of the crucible compared to when the specified member is not provided. This increases the vapor pressure in the crucible, making it possible to suppress evaporation of the raw material melt.

[0006] The predetermined member may have a shape that protrudes laterally from the support shaft and extends from the center of the central axis of the support shaft.

[0007] The outer dimensions of the predetermined member may be smaller than the inner dimensions of the crucible.

[0008] The crucible may have a substantially cylindrical shape. The predetermined member may have a circular shape centered on the central axis of the support shaft.

[0009] The predetermined member may include a first predetermined member and a second predetermined member disposed above the first predetermined member.

[0010] The crystal growth apparatus may further include a partition disposed on the inner wall of the crucible. The partition has a circular opening centered on the central axis of the crucible. The thickness of the partition in the direction of the central axis of the crucible may be a constant first thickness. The inner diameter of the opening may be larger than the outer diameter of the predetermined member. The central axis of the crucible may coincide with the central axis of the support shaft. During crystal growth, at least a portion of the predetermined member may be located within the range of the first thickness.

[0011] The partition may include a first partition and a second partition disposed above the first partition.

[0012] The thickness of the predetermined member in the direction of the central axis of the support shaft may be a constant second thickness. The second thickness may be smaller than the first thickness.

[0013] The gap between the inner diameter of the opening and the outer diameter of the given member may be 0.1 mm or more.

[0014] The predetermined member may be perpendicular to the central axis of the support shaft. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing the basic configuration of a crystal growth apparatus. [Figure 2A] 1 is a schematic configuration diagram of a crystal growth apparatus 1 according to a first embodiment. [Figure 2B] FIG. 2B is a schematic cross-sectional view taken along line II-II in FIG. 2A. [Diagram 3] FIG. 2 is a schematic diagram of the crystal growth apparatus 1, showing a state at the completion of the crystal growth process. [Figure 4] 1 is a crystal growth apparatus of a comparative example. [Diagram 5] This is a crystal growth apparatus according to the present embodiment. [Figure 6] FIG. 1 is a schematic diagram of a crystal growth apparatus 1a according to a second embodiment. [Figure 7] FIG. 11 is a schematic diagram of a crystal growth apparatus 1b according to a fourth embodiment. [Figure 8] FIG. 11 is a schematic diagram of a crystal growth apparatus 1c according to a fourth embodiment. [Figure 9] FIG. 11 is a schematic diagram of a crystal growth apparatus 1d according to a fourth embodiment. [Figure 10] FIG. 11 is a schematic diagram of a crystal growth apparatus 1e according to a fourth embodiment. [Figure 11] FIG. 11 is a schematic diagram of a crystal growth apparatus 1f according to a fourth embodiment. [Figure 12] FIG. 13 is a schematic diagram of a crystal growth apparatus 1g according to Example 4. [Figure 13] FIG. 11 is a schematic diagram of a crystal growth apparatus 1h according to a fourth embodiment. [Figure 14] FIG. 11 is a schematic diagram of a crystal growth apparatus 1i according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] <Basic configuration of crystal growth equipment> FIG. 1 shows a schematic diagram of a crystal growth apparatus 1P. The crystal growth apparatus 1P is an apparatus for liquid phase growth of a SiC crystal. The crystal growth apparatus 1P includes a rotating shaft 12, a support shaft 13, and a crucible 15. The rotating shaft 12 is an axis that supports the crucible 15 so that it can rotate. The crucible 15 is made of a carbon material (graphite). The crucible 15 has a substantially cylindrical shape. A partition wall 31P is disposed on the inner wall 15w of the crucible 15 around the entire circumference of the inner wall surface. The partition wall 31P is freely attachable to and detachable from the inner wall of the crucible 15.

[0017] The crucible 15 contains a raw material melt 17. The raw material melt 17 is a solution of Si. Carbon atoms melt from the crucible 15. An additive element is added to the raw material melt 17 to make carbon easier to dissolve. Examples of the additive element include low melting point metals (Al, Sn, Ga, etc.), transition metals (Ti, Cr, Ni, Fe, etc.), various rare earth elements, etc. In this embodiment, Cr (chromium) and a small amount of Al (aluminum) compared to Cr are used.

[0018] The support shaft 13 includes a crystal support portion 20. The crystal support portion 20 is disposed at the lower end of the support shaft 13. A lower surface 20u of the crystal support portion 20 has a circular shape centered on the central axis CA1 of the support shaft 13. A seed crystal 16 is attached to the lower surface 20u. The seed crystal 16 is a SiC template for growing a SiC crystal 18. In this embodiment, a 4H-SiC single crystal having a disk-like wafer shape (6 inches in diameter) is used as the seed crystal 16. The crystal growth surface of the seed crystal 16 is a surface inclined 1 degree from the (0001) plane to the [11-20] plane.

[0019] <Effects> When the raw material melt 17 evaporates, it adheres to the inner wall of the crucible 15. The adhered raw material melt 17 solidifies as it cools, and the solid matter adheres to the inner wall. In particular, when additive elements such as Cr and Al, which have high vapor pressure, evaporate, solid matter containing these elements adheres to the inner wall. In addition, the longer the crystal growth time, the greater the amount of evaporation of the raw material melt 17, and the greater the amount of adhesion of the solid matter. In the crystal growth apparatus 1P according to the present technology, in a state in which the crystal support part 20 is inserted into the crucible 15 (i.e., in a state in which the SiC crystal is grown), the partition wall 31P is located below the upper end 15u of the crucible 15. This allows the partition wall 31P to function as a lid that covers the upper part of the crucible 15, thereby increasing the airtightness inside the crucible 15. The vapor pressure at the liquid surface of the raw material melt 17 can be increased, thereby suppressing the evaporation of the raw material melt 17. It is possible to suppress adhesion of solid matter such as Cr and Al.

[0020] Hereinafter, an embodiment of a crystal growth apparatus to which the technology disclosed in this specification is applied will be described. In each of the drawings referred to below, components that have substantially the same functions as the components of the crystal growth apparatus 1P described above will be given the same reference numerals, and their description may be omitted. EXAMPLES

[0021] <Configuration of Crystal Growth Apparatus 1> FIG. 2A shows a schematic diagram of the crystal growth apparatus 1. FIG. 2B shows a schematic cross-sectional view taken along line II-II in FIG. 2A. In FIG. 2B, the second plate-shaped member 22 and the second partition wall 32 are painted gray for ease of understanding. Also, in FIG. 2B, the crucible accommodation unit 11 and the high-frequency coil 14 are omitted. The crystal growth apparatus 1 includes the crucible accommodation unit 11, a rotating shaft 12, a supporting shaft 13, a high-frequency coil 14, a crucible 15, a rotating unit 19, and a driving unit 30.

[0022] The crucible accommodation part 11 accommodates the crucible 15. The crucible accommodation part 11 has a function of suppressing heat radiation from the crucible 15 and keeping the crucible 15 at a constant temperature. A circular opening OP3 having an inner diameter ID3 is formed in the upper part of the crucible accommodation part 11. The rotating part 19 is a part that rotates the rotating shaft 12. The rotating shaft 12 is a shaft that supports the crucible 15 so that it can rotate. The central axis CA3 of the rotating shaft 12 coincides with the central axis CA2 of the crucible 15.

[0023] A circular opening OP2 having an inner diameter ID4 is formed at the top of the crucible 15. A first partition 31 and a second partition 32 are arranged on the inner wall 15w of the crucible 15 along the entire circumference of the inner wall surface. The first partition 31 and the second partition 32 have a circular opening OP1 centered on the central axis CA2 of the crucible 15. The second partition 32 is arranged above the first partition 31. The first partition 31 and the second partition 32 function as an integral partition. The distance between the lower surface of the first partition 31 and the upper surface of the second partition 32 corresponds to the thickness T1 of this integral partition.

[0024] Driving unit 30 is a part that rotates support shaft 13 and moves it up and down (in the Z-axis direction in FIG. 2A). High-frequency coil 14 receives power supply from a power supply device (not shown) and induction heats crucible 15.

[0025] <Configuration of Support Shaft 13> The support shaft 13 includes a crystal support portion 20, a first plate-shaped member 21, and a second plate-shaped member 22. The diameter DD of the lower surface 20u is larger than the diameter AD of the support shaft 13. The first plate-shaped member 21 and the second plate-shaped member 22 have a circular shape centered on the central axis CA1 of the support shaft 13. The first plate-shaped member 21 and the second plate-shaped member 22 protrude laterally from the support shaft 13 perpendicularly to the central axis CA1. The second plate-shaped member 22 is disposed above the first plate-shaped member 21. The first plate-shaped member 21 and the second plate-shaped member 22 function as an integral plate-shaped member. The distance between the lower surface of the first plate-shaped member 21 and the upper surface of the second plate-shaped member 22 corresponds to the thickness T2 of this integral plate-shaped member. In this embodiment, the thickness T2 is the same as the thickness T1.

[0026] The diameter DD of the lower surface 20u is equal to the outer diameter OD of the first plate-shaped member 21 and the second plate-shaped member 22. The diameter DD and the outer diameter OD are smaller than the inner diameter ID4 of the crucible 15, the inner diameter ID1 of the opening OP1, the inner diameter ID4 of the opening OP2, and the inner diameter ID3 of the opening OP3. Therefore, the crystal support part 20 can be inserted into the crucible 15 through the openings OP1 to OP3.

[0027] In a state where the crystal support 20 is inserted into the crucible 15 (i.e., in a state where the SiC crystal is grown), the first plate-shaped member 21 and the second plate-shaped member 22 are located below the upper end 15u of the crucible 15. The first plate-shaped member 21 and the second plate-shaped member 22 are surrounded by the first partition wall 31 and the second partition wall 32. This allows the first plate-shaped member 21 and the second plate-shaped member 22 to function as a lid that covers the upper part of the crucible 15. The gap GP between the outer diameter OD of the first plate-shaped member 21 and the second plate-shaped member 22 and the inner diameter ID1 of the opening OP1 is preferably 0.1 mm or more. In this embodiment, it is set to 2 mm. The central axis CA2 of the crucible 15 coincides with the central axis CA1 of the support shaft 13. Therefore, it is possible to rotate the crucible 15 and the support shaft 13 relative to each other while maintaining the gap GP constant over the entire circumference.

[0028] The melting point of the material of the first plate-shaped member 21, the second plate-shaped member 22, the first partition 31, and the second partition 32 is higher than the temperature of the heat radiated from the raw material melt 17, for example, 1000° C. or higher. Examples of such a high melting point material include carbon, silicon, silicon carbide, magnesium oxide, titanium oxide, etc. In this embodiment, carbon is used as the material.

[0029] <Examples of crystal growth> The process of growing a SiC crystal using crystal growth apparatus 1 will be described. In step S1, raw material melt 17 is prepared. Specifically, support shaft 13 is pulled upward from within crucible 15. A Si raw material and additive elements (Cr, Al) are placed in crucible 15. The Si raw material is heated and melted by high-frequency coil 14 to prepare raw material melt 17.

[0030] In step S2, the seed crystal 16 is attached to the lower surface 20u of the support shaft 13. Then, the crystal support part 20 is inserted into the crucible 15 through the openings OP1 to OP3. The seed crystal 16 is brought into contact with the raw material melt 17. This results in the state shown in Fig. 2A. Fig. 2A is a diagram showing the state at the start of the crystal growth process.

[0031] In step S3, crystal growth is performed. Specifically, seed crystal 16 is brought into contact with raw material melt 17, and rotating shaft 12 and support shaft 13 are rotated. Raw material melt 17 is maintained at the crystal growth temperature. As SiC crystal 18 grows, support shaft 13 is pulled up at a predetermined speed. This allows SiC crystal 18 to grow, as shown in Fig. 3. Fig. 3 is a diagram showing the state at the completion of the crystal growth process.

[0032] <Effects> The crystal growth apparatus 1 of this embodiment includes an integral plate-like member (first plate-like member 21 and second plate-like member 22) and an integral partition wall (first partition wall 31 and second partition wall 32). In addition, during the entire period from the start (FIG. 2A) to the end (FIG. 3) of the crystal growth, at least a part of the thickness T2 of the integral plate-like member is positioned within the range of the thickness T1 of the integral partition wall. In other words, the SiC crystal 18 is pulled up so that the integral plate-like member and the integral partition wall always overlap when viewed from the side of the crucible 15. This makes it possible to maintain the gap between the integral plate-like member and the integral partition wall at a constant value of the gap GP during the entire period of the crystal growth. Since the upper part of the crucible 15 can be covered by the integral plate-like member and the integral partition wall, the airtightness inside the crucible 15 can be increased. Since the vapor pressure at the liquid surface of the raw material melt 17 can be increased, the evaporation of the raw material melt 17 can be suppressed. It is possible to suppress adhesion of solid matter such as Cr and Al.

[0033] As shown in FIG. 4 (Comparative Example) and FIG. 5 (Present Example), the liquid raw material melt 17 may rise along the inner wall of the crucible 15, and thus leak upward from the gap GP. As shown in the comparative example of FIG. 4, when a single plate-like member 121 and a partition wall 131 are provided, the raw material melt 17 leaking upward from the gap GP is exposed to the upper space 15s1 of the crucible 15 and the internal space 11s of the crucible housing part 11. Since the volumes of the upper space 15s1 and the internal space 11s are large, the vapor pressure of the upper space 15s1 and the internal space 11s is unlikely to increase even if the leaked raw material melt 17 evaporates. Therefore, it is difficult to increase the vapor pressure of the lower space 15s2 present below the plate-like member 121 and the partition wall 131. On the other hand, in this embodiment of FIG. 5, the integrated plate-shaped member has a space SP1 sandwiched between the double first plate-shaped member 21 and the second plate-shaped member 22. The integrated partition wall also has a space SP2 sandwiched between the first partition wall 31 and the second partition wall 32. Even if the raw material melt 17 leaks upward from the gap GP between the first plate-shaped member 21 and the first partition wall 31, the raw material melt 17 can be confined in the spaces SP1 and SP2. The raw material melt 17 in the spaces SP1 and SP2 can be evaporated by the radiant heat from the raw material melt 17. The volumes of the spaces SP1 and SP2 are sufficiently smaller than the volumes of the upper space 15s1 and the internal space 11s, so that the vapor pressure in the spaces SP1 and SP2 can be increased. Therefore, the lower space 15s2 below the spaces SP1 and SP2, which have high vapor pressure, can be sealed, so that the vapor pressure in the lower space 15s2 can be increased. This makes it possible to suppress the evaporation of the raw material melt 17. EXAMPLES

[0034] Fig. 6 shows a crystal growth apparatus 1a according to Example 2. The crystal growth apparatus 1a of Example 2 is different from the crystal growth apparatus 1 of Example 1 (Fig. 2A) in that it further includes a third partition 33 and a fourth partition 34. The same components as those of Example 1 are denoted by the same reference numerals, and description thereof will be omitted.

[0035] First partition 31 to fourth partition 34 function as an integral partition. The distance between the lower surface of first partition 31 and the upper surface of fourth partition 34 corresponds to thickness T3 of this integral partition. Thickness T2 of the integral plate-like member consisting of first plate-like member 21 and second plate-like member 22 is smaller than thickness T3. During crystal growth, SiC crystal 18 is pulled up so that at least a part of thickness T2 of the integral plate-like member is located within the range of thickness T3 of the integral partition. Since thickness T3 can be made thicker than thickness T1 of the integral partition in crystal growth apparatus 1 of Example 1 (FIGS. 2A and 3), the pulling distance of SiC crystal 18 can be increased. Since the ingot of SiC crystal 18 can be made longer, costs can be reduced. EXAMPLES

[0036] In the third embodiment, a form in which the shapes of the first plate-shaped member 21 and the second plate-shaped member 22 are optimized using a machine learning algorithm will be described. Here, the shapes of the first plate-shaped member 21 and the second plate-shaped member 22 may be various shapes as shown below. For example, it may be the thickness T2 (the distance between the lower surface of the first plate-shaped member 21 and the lower surface of the second plate-shaped member 22) or the height of the space SP1 (the distance between the upper surface of the first plate-shaped member 21 and the lower surface of the second plate-shaped member 22). It may be the thickness of the first plate-shaped member 21 itself or the thickness of the second plate-shaped member 22 itself. It may be the value of the gap GP. It may be the outer diameter OD of the first plate-shaped member 21 and the second plate-shaped member 22. It may also be a combination of a plurality of these shapes.

[0037] The regression model for calculating the shapes of the first plate-shaped member 21 and the second plate-shaped member 22 is created using regression by machine learning (e.g., neural network). Creating a regression model by machine learning requires the collection of training data. Therefore, in the technology of this specification, training data is collected by simulation using analysis software.

[0038] A specific description will be given. A three-dimensional model of the crystal growth apparatus 1 is created from CAD data. Then, a simulation calculation is performed using an input parameter set. As an example of the input parameter set, the power supplied to the high-frequency coil 14, the air temperature inside the crucible housing part 11, the rotation speed of the crucible 15, the rotation speed of the support shaft 13, etc. are used. Each time a simulation is performed, an output result for one input parameter set (the temperature distribution inside the raw material melt 17, the evaporation amount of the raw material melt 17) is obtained. By repeating the simulation for multiple input parameter sets, multiple training data are obtained. Then, machine learning is performed using the multiple acquired training data to create a regression model.

[0039] The created regression model is used to calculate the shapes of the first plate-shaped member 21 and the second plate-shaped member 22. The temperature distribution inside the raw material melt 17 and the amount of evaporation of the raw material melt 17 change depending on the shapes of the first plate-shaped member 21 and the second plate-shaped member 22. Therefore, a shape that can achieve both suppression of the amount of evaporation of the raw material melt 17 and appropriate temperature distribution inside the raw material melt 17 is searched for using the regression model. This makes it possible to optimize the shapes of the first plate-shaped member 21 and the second plate-shaped member 22. The shapes of the first partition 31 and the second partition 32 can also be optimized using the regression model. EXAMPLES

[0040] In the fourth embodiment, crystal growth apparatuses 1b to 1i having various modified structures are listed. The same components as those in the first embodiment are given the same reference numerals and will not be described. The crystal growth apparatus 1b shown in FIG. 7 is an example that does not have a plate-like member protruding from the support shaft 13. The first partition wall 31b and the second partition wall 32b are detachable from the inner wall of the crucible 15. Therefore, even if the diameter DD of the crystal support part 20 is larger than the inner diameter ID1, the crystal support part 20 can be inserted into and removed from the crucible 15.

[0041] The crystal growth apparatus 1c in FIG. 8 is provided with one thick first partition wall 31c in comparison with the crystal growth apparatus 1b in FIG.

[0042] A crystal growth apparatus 1d in Fig. 9 does not include the crystal support portion 20, unlike the crystal growth apparatus 1b in Fig. 7. A seed crystal 16d is disposed at the lower end of the support shaft 13.

[0043] In the crystal growth apparatus 1e of Fig. 10, the first plate-shaped member 21e and the first partition wall 31e have an uneven portion in the cross-sectional shape so that they can fit together. In the crystal growth apparatus 1f of Fig. 11, the first plate-shaped member 21f and the first partition wall 31f have a tapered portion in the cross-sectional shape so that they can fit together. This can increase the airtightness of the raw material melt 17.

[0044] In a crystal growth apparatus 1g of FIG. 12, the cross sections of a first member 21g and a first partition wall 31g are semicircular.

[0045] Fig. 13(A) is a cross-sectional view of the crystal growth apparatus 1h, and Fig. 13(B) is a top view thereof. A plurality of holes H1 are formed in the first partition wall 31h. Fig. 14(A) is a cross-sectional view of the crystal growth apparatus 1i, and Fig. 14(B) is a top view thereof. A plurality of holes H1 are formed in the first plate-shaped member 21i. The arrangement of the holes H1 may be random or regular.

[0046] <Modification> Although the embodiments of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

[0047] The shapes of the first plate-shaped member 21 and the second plate-shaped member 22 are not limited to a circle centered on the central axis CA1, and the shape of the crucible 15 is not limited to a cylinder. It may be various shapes such as a polygon.

[0048] The first partition 31 and the second partition 32 may be omitted. Since the upper part of the crucible 15 can be covered by the first plate-shaped member 21 and the second plate-shaped member 22, evaporation of the raw material melt 17 can be suppressed.

[0049] A solid material having a composition similar to that of the raw material melt 17 may be placed in advance in the spaces SP1 and SP2 (FIG. 5). This solid material melts and evaporates due to radiant heat, so that the vapor pressure in the spaces SP1 and SP2 can be reliably increased.

[0050] The plate-like members are not limited to a two-piece configuration of the first plate-like member 21 and the second plate-like member 22. There may be one piece, or three or more pieces. The partition walls are not limited to a multiple-piece configuration of the first partition wall 31 to the fourth partition wall 34. There may be one piece, or five or more pieces.

[0051] The first plate-like member 21 and the second plate-like member 22 are not limited to protruding perpendicularly to the central axis CA1 of the support shaft 13. They may protrude obliquely upward or downward, or may protrude with a curved surface.

[0052] The plate-like member is not limited to being disposed inside the crucible 15. It may be disposed above the crucible 15. For example, the crystal growth apparatus may include a seal portion disposed above the crucible 15 and in the vicinity of the opening OP3 of the crucible accommodation portion 11. The seal portion includes a plurality of plate-like members protruding laterally from the support shaft 13. The plurality of plate-like members have a circular shape centered on the central axis CA1 of the support shaft 13. The outer diameter of the seal portion is smaller than the inner diameter ID3 of the opening OP3 of the crucible accommodation portion 11. The seal portion can increase the airtightness of the crucible accommodation portion 11.

[0053] Diameter DD of lower surface 20u may be smaller than outer diameter OD of first plate-shaped member 21 and second plate-shaped member 22. Diameter DD can be set appropriately in accordance with the wafer diameter of SiC crystal 18 to be grown.

[0054] The crystal growth apparatus 1 of the present specification can be applied to any crystal growth as long as the crystal can be grown by a liquid phase epitaxy method using a high-temperature melt. For example, various semiconductor crystals such as GaN, GaAs, and AlN can be grown.

[0055] The material of the raw material solution is not particularly limited, and a general material can be used. For example, the Si source of the raw material solution can be Si or a Si alloy. The C source of the raw material solution can be graphite, glassy carbon, SiC, or a hydrocarbon gas such as methane, ethane, propane, or acetylene.

[0056] Various crystal polytypes, such as 4H-SiC and 6H-SiC, can be used as the seed crystal 16. The crystal growth surface of the seed crystal 16 is not limited to the (0001) surface, and various surfaces can be used.

[0057] The technical elements described in this specification or drawings have technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically useful.

[0058] The first plate-shaped member 21 and the second plate-shaped member 22 are examples of a predetermined member. [Explanation of symbols]

[0059] 1, 1a: crystal growth apparatus 13: support shaft 15: crucible 16: seed crystal 17: raw material melt 18: SiC crystal 20: crystal support 21: first plate-shaped member 22: second plate-shaped member 31: first partition wall 32: second partition wall CA1-CA3: central axis DD: diameter OD: outer diameter ID1-ID4: inner diameter T1, T2: thickness

Claims

1. A crucible having a substantially cylindrical shape and capable of containing a raw material melt; a support shaft that can be inserted into the crucible from above and can be rotated and raised and lowered, and a seed crystal can be attached to a lower end of the support shaft; A predetermined member is disposed in a direction intersecting the support shaft and has a circular shape centered on a central axis of the support shaft; Equipped with The predetermined member is A first predetermined member; a second predetermined member disposed above the first predetermined member; It is equipped with A crystal growth apparatus, wherein the predetermined member is located below an upper end of the crucible during crystal growth.

2. A crucible having a substantially cylindrical shape and capable of containing a raw material melt; a support shaft that can be inserted into the crucible from above and can be rotated and raised and lowered, and a seed crystal can be attached to a lower end of the support shaft; A predetermined member is disposed in a direction intersecting the support shaft and has a circular shape centered on a central axis of the support shaft; A partition wall disposed on an inner wall of the crucible, the partition wall having a circular opening centered on a central axis of the crucible; Equipped with The partition wall is A first partition wall; a second partition wall disposed above the first partition wall; It is equipped with the partition has a first constant thickness in a direction of a central axis of the crucible; The inner diameter of the opening is larger than the outer diameter of the predetermined member, The central axis of the crucible coincides with the central axis of the support shaft, A crystal growth apparatus, wherein during crystal growth, the specified member is located below an upper end of the crucible, and at least a portion of the specified member is located within the first thickness range.

3. A crucible having a substantially cylindrical shape and capable of containing a raw material melt; a support shaft that can be inserted into the crucible from above and can be rotated and raised and lowered, and a seed crystal can be attached to a lower end of the support shaft; A predetermined member is disposed in a direction intersecting the support shaft and has a circular shape centered on a central axis of the support shaft; A partition wall disposed on an inner wall of the crucible, the partition wall having a circular opening centered on a central axis of the crucible; Equipped with the partition has a first constant thickness in a direction of a central axis of the crucible; The inner diameter of the opening is larger than the outer diameter of the predetermined member, The central axis of the crucible coincides with the central axis of the support shaft, At least one of a thickness of the predetermined member in a direction of a central axis of the support shaft, a gap between an inner diameter of the opening and an outer diameter of the predetermined member, and a diameter of the predetermined member is determined using a regression model based on machine learning; the regression model is a model derived by the machine learning using training data including a temperature distribution inside the raw material melt and an evaporation amount of the raw material melt obtained by a simulation, A crystal growth apparatus, wherein during crystal growth, the specified member is located below an upper end of the crucible, and at least a portion of the specified member is located within the first thickness range.

4. 4. The crystal growth apparatus according to claim 1, wherein the predetermined member protrudes laterally from the support shaft and has a shape extending from the center of a central axis of the support shaft.

5. 5. The crystal growth apparatus according to claim 1, wherein an outer dimension of the predetermined member is smaller than an inner dimension of the crucible.

6. The thickness of the predetermined member in a direction of a central axis of the support shaft is a constant second thickness, 4. A crystal growing apparatus as claimed in claim 2 or 3, wherein the second thickness is less than the first thickness.

7. 4. The crystal growing apparatus according to claim 2, wherein a gap between an inner diameter of the opening and an outer diameter of the predetermined member is 0.1 mm or more.

8. 8. The crystal growth apparatus according to claim 1, wherein the predetermined member is perpendicular to a central axis of the support shaft.

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