A device and method for growing cylindrical silicon carbide single crystal by liquid phase method

Abstract

The present invention relates to the technical field of preparation of silicon carbide single crystals, and in particular to a device and method for growing cylindrical silicon carbide single crystals by a liquid phase method. The device includes a heat dissipation control device installed above a silicon carbide seed crystal, including six edges with an angle of 60° and equal length, the endpoints of each edge away from the center are connected by a circular arc concave toward the center, and different edges are connected by a downwardly concave curved surface. The thickness of the portion where the edge is located is the largest, and the heat dissipation is the slowest. The thickness of the position of the bisector of the angle formed by two adjacent edges is the smallest, and the heat dissipation is the fastest; the crystal direction of the seed crystal is controlled to be consistent with the direction of the edge, and the crystal direction of the seed crystal is consistent with the angle bisector of two adjacent edges. The present invention provides a device and method for growing cylindrical silicon carbide single crystals by a liquid phase method, which can effectively suppress the anisotropy of the growth rate of silicon carbide crystals in liquid phase growth, and prepare cylindrical silicon carbide crystals to reduce the difficulty and cost of wafer processing.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of silicon carbide single crystals, and in particular to a device and method for growing cylindrical silicon carbide single crystals by a liquid phase method. Background Art

[0002] As one of the typical representatives of wide bandgap semiconductors, silicon carbide has excellent properties such as large bandgap width, high breakdown field strength, high saturated electron mobility, high thermal conductivity, good thermal stability and chemical stability. It is an ideal substrate material for making high-frequency, high-voltage, high-efficiency, radiation-resistant, high-temperature resistant high-power devices and blue light-emitting diodes, which makes it have huge application prospects in new energy vehicles, high-speed rail transit, aerospace, high-voltage smart grids and clean energy. Therefore, it has received widespread attention from academia and governments of various countries.

[0003] Liquid phase growth is an important method for preparing silicon carbide single crystals. It requires a low growth temperature and a relatively stable growth environment, and can achieve crystal growth in a near-equilibrium state. Not only is the growth cost relatively low, but in theory, it can also achieve higher crystal quality. In addition, the liquid phase method also has good application prospects in obtaining P-type substrates and expanding crystal diameters. Therefore, in recent years, the liquid phase method has received more and more attention, and related technologies have also made breakthrough progress. In the liquid phase growth of silicon carbide single crystals, due to the strong anisotropy of the solid-liquid interface energy between the silicon carbide crystal and the high-temperature solution, the crystal The solid-liquid interface energy between the crystal face family and the high-temperature solution is much lower than The solid-liquid interface energy between the crystal face family and the high-temperature solution. Therefore, when the crystal grows in the liquid phase, The growth rate along The growth rate in the direction of the crystal is very fast, which eventually leads to the crystal developing into a hexagonal shape. Hexagonal crystals are difficult to process wafers, with high costs, and are prone to inducing cracks that lead to crystal cracking. It is of great significance to develop a device that can grow cylindrical SiC crystals through liquid phase. Summary of the invention

[0004] The embodiment of the present invention provides a device and method for growing a cylindrical silicon carbide single crystal by a liquid phase method, which can prepare a cylindrical silicon carbide crystal.

[0005] In a first aspect, an embodiment of the present invention provides a device for growing cylindrical silicon carbide crystals by a liquid phase method, comprising a heat dissipation control device installed above a silicon carbide seed crystal,

[0006] The heat dissipation control device is thick in the middle and thin around, and has an anisotropic structure with six-fold symmetry, including six edges with an angle of 60° and equal length, the endpoints of each edge away from the center are connected by a circular arc concave toward the center, and different edges are connected by a downwardly concave curved surface, so that the thickness of the part where the edge is located at the same distance from the center of the heat dissipation control device is the largest, the heat dissipation rate is the smallest, and the thickness of the position of the bisector of the angle formed by two adjacent edges is the smallest, and the heat dissipation rate is the largest;

[0007] The heat dissipation control device maintains a fixed corresponding relationship with the crystal orientation of the silicon carbide seed crystal when installed. The crystal direction is consistent with the edge direction, and the silicon carbide seed crystal The crystal direction is consistent with the angle bisector of two adjacent edges.

[0008] In a possible design, a vertical projection of the arc is tangent to a vertical projection of the seed crystal.

[0009] In a possible design, a reference circle is made with the center of the heat dissipation control device as the center and the distance between the axis of the heat dissipation control device and the midpoint of the arc as the radius. Within the range of the reference circle, in a portion with the same length from the axis of the heat dissipation control device, the ratio of the thickness of the edge to the thickness of the bisector of the adjacent edge is 2:1~10:1. Outside the range of the reference circle, the thickness decreases to 1~5 mm in the direction away from the edge and away from the center of the reference circle.

[0010] In a possible design, it also includes a first rotating lifting shaft, a seed crystal holder and a locking sleeve. The first rotating lifting shaft is used to transmit the driving force required for lifting and rotation. The lower part of the seed crystal holder is connected to the seed crystal. The upper part of the seed crystal holder is provided with a connecting shaft. The connecting shaft passes through a through hole at the center position of the heat dissipation control device and is detachably connected to the first rotating lifting shaft. The heat dissipation control device and the seed crystal holder are driven by the rotating lifting rod to rotate and lift synchronously.

[0011] In a possible design, the connecting shaft passes through a through hole in the middle position of the heat dissipation control device and is snap-connected with the first rotating lifting shaft. The locking sleeve is sleeved on the first rotating lifting shaft, and the locking sleeve is used to lock the snap-connection between the connecting shaft and the first rotating lifting shaft.

[0012] In a possible design, it also includes a growth furnace and a growth crucible located in the growth furnace, the growth furnace is provided with an induction coil for heating, the growth crucible is filled with a high-temperature melt, the outside of the growth crucible is wrapped with a heat-insulating material, a growth crucible support plate is provided at the bottom, and a second rotating pulling axis for pulling and rotating is provided at the bottom of the growth crucible support plate.

[0013] In a possible design, the growth crucible is a graphite crucible, and the composition and ratio of the high-temperature melt in the growth crucible are: Si:Cr:Cu:Al=70:20:5:5.

[0014] In a second aspect, an embodiment of the present invention further provides a method for growing cylindrical silicon carbide crystals by a liquid phase method, based on any of the above-mentioned devices, the method comprising:

[0015] The heat dissipation control device is arranged above the seed crystal;

[0016] Adjust the positional relationship between the heat dissipation control device and the seed crystal so that the silicon carbide seed crystal The crystal direction is consistent with the edge direction, and the silicon carbide seed crystal The crystal direction is consistent with the angle bisector of two adjacent edges;

[0017] Start growing silicon carbide crystals by liquid phase method.

[0018] In one possible design, the growth temperature of the liquid phase silicon carbide crystal is 1700~1900℃.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] The crystal structure of SiC determines that there are obvious differences in its growth rate along different crystal directions during liquid phase growth, that is, there is obvious anisotropy in the growth rate, which is the fundamental reason why SiC crystals are very easy to develop into hexagons when growing in liquid phase. Based on the basic principle of crystal growth, the present invention provides a heat dissipation control device with a six-fold symmetric structure. The main structural features of the device are: in the six equivalent first characteristic directions with an angle of 60 degrees to each other, that is, on the six edges, it is designed to be a structure with large thickness and large size. In this way, it can play a role in suppressing heat dissipation, and adjust the position of the heat dissipation control device to keep it consistent with the crystal direction of the seed crystal of the growth rate block, by suppressing the SiC crystal from growing at a fast rate. The heat dissipation rate in the crystal direction is used to suppress the SiC crystal The growth rate of the crystal direction; in the other six second characteristic directions, which are 30 degrees apart from the above six directions, that is, the angle bisectors of the adjacent edges, a structure with a small thickness and a small size is set, so that the heat dissipation can be accelerated, and the position of the heat dissipation control device is adjusted to be consistent with the crystal direction of the seed crystal with a slow growth rate, by accelerating the SiC crystal in the slow growth rate The heat dissipation rate in the crystal direction is used to accelerate the SiC crystal In summary, by suppressing the direction with fast growth rate and promoting the direction with slow growth rate, the obtained silicon carbide crystal is made cylindrical. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 1 is a schematic structural diagram of a device for vapor phase growth of silicon carbide single crystals provided in an embodiment of the present invention;

[0023] Figure 2 It is a schematic diagram of the installation process of a connecting column and a first rotating lifting shaft provided by an embodiment of the present invention;

[0024] Figure 3 It is a schematic diagram of the relationship between a heat dissipation control device and a seed crystal orientation provided by an embodiment of the present invention;

[0025] Figure 4 The silicon carbide crystal prepared in Example 1 of the present invention;

[0026] Figure 5 The silicon carbide crystal prepared in Comparative Example 1 of the present invention;

[0027] Figure 6 This is the silicon carbide crystal prepared in Comparative Example 2 of the present invention.

[0028] In the figure:

[0029] 1-first rotating lifting axis; 2-growth furnace; 3-insulating material; 4-growth crucible; 5-seed crystal holder; 6-induction coil; 7-silicon carbide seed crystal; 8-high temperature melt; 9-crucible support plate; 10-second rotating lifting axis; 11-heat dissipation control device; 12-locking sleeve. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple" refers to two or more; the terms "connected" and "fixed" should be understood in a broad sense, for example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] In the description of this specification, it should be understood that the directional words such as "upper" and "lower" described in the embodiments of the present invention are described at the angles shown in the drawings and should not be understood as limiting the embodiments of the present invention. In addition, in the context, it should also be understood that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0033] like Figures 1 to 3 As shown, an embodiment of the present invention provides a device for growing cylindrical silicon carbide crystals by a liquid phase method.

[0034] It includes a heat dissipation control device 11 installed above the silicon carbide seed crystal 7, the heat dissipation control device 11 is thick in the middle and thin around, and has a six-fold symmetric anisotropic structure, including six edges with an angle of 60° and equal length, and the endpoints of each edge away from the center are connected by a circular arc concave toward the center, and the radius of the circular arc is the same as the radius of the silicon carbide seed crystal 7, and different edges are connected by downwardly concave curved surfaces, so that the thickness of the part where the edge is located at the same distance from the center of the heat dissipation control device 11 is the largest, and the heat dissipation rate is the smallest, and the thickness of the position of the bisector of the angle formed by two adjacent edges is the smallest and thinnest, and the heat dissipation rate is the largest;

[0035] The heat dissipation control device maintains a fixed corresponding relationship with the crystal orientation of the silicon carbide seed crystal when installed. The crystal direction is consistent with the edge direction, and the silicon carbide seed crystal The crystal direction is consistent with the angle bisector of two adjacent edges.

[0036] The crystal structure of SiC determines that there are obvious differences in its growth rate along different crystal directions during liquid phase growth, that is, there is obvious anisotropy in the growth rate, which is the fundamental reason why SiC crystals are very easy to develop into hexagons when growing in liquid phase. Based on the basic principle of crystal growth, the present invention provides a heat dissipation control device 11 with a six-fold symmetric structure. The main structural features of the device are: in the six equivalent first characteristic directions with an angle of 60 degrees to each other, that is, on the six edges, it is designed to be a structure with large thickness and large size, so that it can play a role in suppressing heat dissipation, and adjust the position of the heat dissipation control device 11 to make it consistent with the seed crystal of the growth rate block. The crystal orientation is kept consistent, by suppressing the SiC crystal growth rate The heat dissipation rate in the crystal direction is used to suppress the SiC crystal The growth rate of the crystal direction; in the other six second characteristic directions, which are 30 degrees apart from the above six directions, that is, the angle bisectors of the adjacent edges, a structure with a small thickness and a small size is set, so that the heat dissipation can be accelerated, and the position of the heat dissipation control device 11 is adjusted to be consistent with the crystal direction of the seed crystal with a slow growth rate, by accelerating the SiC crystal in the slow growth rate The heat dissipation rate in the crystal direction is used to accelerate the SiC crystal In summary, by suppressing the direction with fast growth rate and promoting the direction with slow growth rate, the obtained silicon carbide crystal is made cylindrical.

[0037] Specifically, the heat dissipation control device 11 that is thick in the middle and thin around can make the thickness of the obtained silicon carbide crystal more uniform. In the circumferential direction, the thickness of the heat dissipation control device 11 is thick in the direction of fast growth, slowing down the growth, and the thickness of the heat dissipation control device 11 is thin in the direction of slow growth, accelerating the growth. In order to obtain silicon carbide crystals with high circularity and uniform thickness, the thickness change is gradual. Since the first characteristic direction is thicker than the thickness in the second characteristic direction, the closer to the edge of the second characteristic direction, the thinner it is, and finally the thickness in this direction first drops to 0, that is, the final length of the second characteristic direction is shorter than the first characteristic direction. It should be noted that since the thickness in the circumferential direction is gradual, the part between the first characteristic direction and the second characteristic direction is also gradual, that is, the length of the first characteristic direction is the longest, and as the angle gradually approaches the second characteristic direction, the length from the center to the edge gradually becomes shorter, and the vertical projection of the heat dissipation control device 11 finally obtained is composed of six arcs.

[0038] In some embodiments of the present invention, the vertical projection of the arc is tangent to the vertical projection of the seed crystal 7. This arrangement can ensure that the heat dissipation rate does not change suddenly, make the change of the heat dissipation rate smoother, and fully cover the entire seed crystal.

[0039] In some embodiments of the present invention, a reference circle is made with the center of the heat dissipation control device 11 as the center and the distance between the axis of the heat dissipation control device 11 and the midpoint of the arc as the radius. Within the range of the reference circle, in the portion with the same length from the axis of the heat dissipation control device 11, the ratio of the thickness of the edge to the thickness of the bisector of the adjacent edge is 10:1. Outside the range of the reference circle, the thickness decreases to 1 mm in the direction away from the edge and away from the center of the reference circle.

[0040] In this embodiment, by setting the above parameters, the heat dissipation rate of different parts can be adjusted, and finally the obtained silicon carbide crystal is round.

[0041] In some embodiments of the present invention, a first rotating lifting shaft 1, a seed crystal holder 5 and a locking sleeve 12 are also included. The first rotating lifting shaft 1 is used for lifting and rotating. The lower part of the seed crystal holder 5 is connected to the seed crystal 7. A connecting shaft is provided on the upper part of the seed crystal holder 5. The connecting shaft passes through a through hole at the center position of the heat dissipation control device 11 and is detachably connected to the first rotating lifting shaft 1. The heat dissipation control device and the seed crystal holder are driven by the rotating lifting rod to rotate and lift synchronously.

[0042] In this embodiment, the detachably connected connecting shaft and the first rotating lifting shaft 1 can remove the seed crystal holder 5 and the silicon carbide crystal grown thereunder after the growth is completed, thereby realizing the reuse of the heat dissipation control device 11 .

[0043] In some embodiments of the present invention, the connecting shaft passes through the through hole in the middle position of the heat dissipation control device 11 and is snap-connected with the first rotating lifting shaft 1. The locking sleeve 12 is sleeved on the first rotating lifting shaft 1, and the locking sleeve 12 is used to lock the snap-connection between the connecting shaft and the first rotating lifting shaft 1.

[0044] In some embodiments of the present invention, a growth furnace 2 and a growth crucible 4 located in the growth furnace 2 are further included. The growth furnace 2 is provided with an induction coil 6 for heating. The growth crucible 4 is filled with a high-temperature melt 8. The growth crucible 4 is wrapped with a heat-insulating material 3 on the outside. A crucible support plate 9 is provided at the bottom. A second rotating lifting shaft 10 for lifting and rotating is provided at the bottom of the crucible support plate 9.

[0045] In some embodiments of the present invention, the growth crucible 4 is a graphite crucible, and the composition and ratio of the high-temperature melt 8 in the growth crucible 4 are: Si:Cr:Cu:Al=70:20:5:5.

[0046] The embodiment of the present invention further provides a method for growing cylindrical silicon carbide crystals by a liquid phase method, based on any of the above-mentioned devices, the method comprising:

[0047] A heat dissipation control device 11 is provided above the seed crystal 7;

[0048] Adjust the positional relationship between the heat dissipation control device 11 and the seed crystal 7 so that the silicon carbide seed crystal 7 The direction is consistent with the edge direction, and the silicon carbide seed crystal 7 The direction is consistent with the angle bisector of two adjacent edges;

[0049] Start growing silicon carbide crystals by liquid phase method.

[0050] In some embodiments of the present invention, the growth temperature of the liquid phase silicon carbide crystal is 1700-1900°C.

[0051] The embodiment of the present invention also provides a more specific method for growing silicon carbide crystals by liquid phase method:

[0052] The co-solvent raw materials are loaded into the graphite crucible according to the proportion;

[0053] The silicon carbide seed crystal is bonded to the seed crystal holder 5 according to the specific orientation requirements, and the heat dissipation control device 11 is installed on the seed crystal holder 5. Here, it is necessary to ensure that the silicon carbide seed crystal The crystal direction is consistent with the first characteristic direction of the heat dissipation control device 11 .

[0054] Connect the seed crystal rod to the seed crystal holder 5, and then install the locking sleeve 12;

[0055] Place the above crucible and the installed seed crystal related components into the single crystal growth furnace 2, and place the heat insulation material 3 around the crucible;

[0056] Fix the seed crystal rod on the rotating lifting device of the equipment, and ensure that the seed crystal position is higher than the raw material surface;

[0057] Close the furnace chamber and evacuate the chamber. When the chamber pressure is less than or equal to 10 -4 After Pa, protective gas is filled into the furnace chamber;

[0058] The crucible is heated to completely liquefy the co-solvent raw material in the crucible, and then allowed to stand for a period of time;

[0059] Slowly push the seed crystal down until it is in complete contact with the liquid surface, and crystal growth begins;

[0060] After the crystal growth starts, the crystal growth furnace is controlled so that the seed crystal is driven by the seed crystal rotating and pulling shaft to periodically rotate forward and reverse and slowly pull upward; the crucible is driven by the crucible rotating shaft and pulling shaft to periodically rotate forward and reverse and slowly move upward; wherein the rotation period of the crucible and the seed crystal is consistent and the rotation directions of the two are always opposite;

[0061] After the growth is completed, the crystal is slowly pulled away from the liquid surface and then slowly cooled;

[0062] After the crystal cools to room temperature, open the furnace chamber, remove the seed crystal rod, and remove the locking sleeve 12 to separate the seed crystal rod, the heat dissipation control device 11, and the seed crystal holder 5; after the crystal is removed from the seed crystal holder 5, the seed crystal holder 5, the heat dissipation control device 11, the seed crystal rod, and the locking sleeve 12 can be reused.

[0063] In order to more clearly illustrate the technical solutions and advantages of the present invention, several embodiments are described in detail below.

[0064] Example 1

[0065] This embodiment adopts the device and method provided by the present invention to carry out liquid phase growth of silicon carbide single crystal, and the main steps are as follows:

[0066] The growth raw materials are loaded into a graphite crucible according to the ratio, wherein the composition and ratio of the raw materials are: Si:Cr:Cu:Al=70:20:5:5, the total mass of the raw materials is 12 kg, and the diameter of the crucible is 170 mm;

[0067] According to the specific orientation requirements, a 6-inch diameter silicon carbide seed crystal is bonded to the seed crystal holder 5, and a heat dissipation control device 11 is installed on the seed crystal holder 5, while ensuring that the silicon carbide seed crystal The crystal direction is consistent with the first characteristic direction of the heat dissipation control device 11 .

[0068] Connect the seed crystal rod to the seed crystal holder 5, and then install the locking sleeve 12;

[0069] Place the above crucible and the installed seed crystal related components into the single crystal growth furnace 2, and place the heat insulation material 3 around the crucible;

[0070] Fix the seed crystal rod on the rotating lifting device of the equipment, and ensure that the seed crystal position is higher than the raw material surface;

[0071] Close the furnace chamber and evacuate the chamber. When the chamber pressure is less than or equal to 10 -4 After Pa, Ar protective gas is filled into the furnace chamber;

[0072] The crucible is heated to completely liquefy the solvent raw material in the crucible, and the temperature is maintained at 1900°C and allowed to stand for a period of time;

[0073] Slowly push the seed crystal down until it is in complete contact with the liquid surface, and crystal growth begins;

[0074] After the crystal growth starts, the crystal growth furnace is controlled so that the seed crystal is driven by the seed crystal rotating and pulling shaft to periodically rotate forward and reverse and slowly pull upward; the crucible is driven by the crucible rotating shaft and pulling shaft to periodically rotate forward and reverse and slowly move upward; wherein the rotation period of the crucible and the seed crystal is consistent and the rotation directions of the two are always opposite;

[0075] After the growth is completed, the crystal is slowly pulled away from the liquid surface and then slowly cooled;

[0076] After the crystals have cooled to room temperature, open the furnace cover and take out the grown crystals.

[0077] Figure 4 The 6-inch silicon carbide crystal grown by the device and method provided by the present invention has a round shape and a very bright surface, reflecting a high crystal quality, indicating that the method effectively suppresses the development of the crystal into a hexagon.

[0078] Comparative Example 1

[0079] The heat dissipation control device 11 is not used, and the rest is the same as that of the first embodiment.

[0080] like Figure 5 As shown, the silicon carbide crystal obtained in Comparative Example 1 has a hexagonal shape with obvious edges and corners.

[0081] Comparative Example 2

[0082] When installing the heat dissipation control device 11, the silicon carbide seed crystal The crystal direction is consistent with the second characteristic direction of the heat dissipation control device 11, that is, it is exactly opposite to the installation method required by the present invention, and other processes remain unchanged.

[0083] like Figure 6 As shown, the six corners of the crystal obtained in Comparative Example 2 are still very obvious, and the six sides also show obvious signs of shrinking inwards. Therefore, not assembling in accordance with the method provided by the present invention will not only fail to eliminate the hexagonal corners, but will also cause the crystal diameter to shrink. The diameter reduction will make it impossible to process wafers of standard size.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for growing cylindrical silicon carbide crystals by liquid phase method, characterized in that: The heat dissipation control device (11) is installed above the silicon carbide seed crystal (7), the heat dissipation control device (11) is thick in the middle and thin around the edges, and has a six-fold symmetric anisotropic structure, including six edges with an angle of 60° and equal length, the endpoints of each edge away from the center are connected by a circular arc concave toward the center, and different edges are connected by a curved surface concave downward, so that the thickness of the part where the edge is located at the same distance from the center of the heat dissipation control device (11) is the largest and the heat dissipation rate is the smallest, and the thickness of the position of the bisector of the angle formed by two adjacent edges is the smallest and the heat dissipation rate is the largest; The heat dissipation control device maintains a fixed corresponding relationship with the crystal orientation of the silicon carbide seed crystal when installed. The crystal direction is consistent with the edge direction, and the silicon carbide seed crystal The crystal direction is consistent with the angle bisector of two adjacent edges.

2. The device according to claim 1, characterized in that The vertical projection of the circular arc is tangent to the vertical projection of the silicon carbide seed crystal (7).

3. The device according to claim 1, characterized in that A reference circle is made with the center of the heat dissipation control device (11) as the center of the circle and the distance between the axis of the heat dissipation control device (11) and the midpoint of the arc as the radius. Within the range of the reference circle, in a portion with the same length from the axis of the heat dissipation control device (11), the ratio of the thickness of the edge to the thickness at the bisector of the adjacent edge is 2:1 to 10:

1. Outside the range of the reference circle, the thickness decreases to 1 to 5 mm in a direction away from the edge and away from the center of the reference circle.

4. The device according to claim 1, characterized in that It also includes a first rotating lifting shaft (1), a seed crystal holder (5) and a locking sleeve (12), wherein the first rotating lifting shaft (1) is used for lifting and rotating, the lower part of the seed crystal holder (5) is connected to the silicon carbide seed crystal (7), and the upper part of the seed crystal holder (5) is provided with a connecting shaft, the connecting shaft passes through a through hole at the center position of the heat dissipation control device (11) and is detachably connected to the first rotating lifting shaft (1), and the heat dissipation control device and the seed crystal holder are driven by the rotating lifting rod to rotate and lift synchronously.

5. The device according to claim 4, characterized in that The connecting shaft passes through a through hole in the middle of the heat dissipation control device (11) and is snap-connected with the first rotating lifting shaft (1); the locking sleeve (12) is sleeved on the first rotating lifting shaft (1); the locking sleeve (12) is used to lock the snap-connected connection between the connecting shaft and the first rotating lifting shaft (1).

6. The device according to claim 1, characterized in that It also includes a growth furnace (2) and a growth crucible (4) located in the growth furnace (2), wherein an induction coil (6) for heating is arranged in the growth furnace (2), a high-temperature melt (8) is contained in the growth crucible (4), the growth crucible (4) is wrapped with a heat-insulating material (3) on the outside, a crucible support plate (9) is arranged at the bottom, and a second rotating lifting shaft (10) for lifting and rotating is arranged at the bottom of the crucible support plate (9).

7. The device according to claim 6, characterized in that The growth crucible (4) is a graphite crucible, and the composition and proportion of the high-temperature melt (8) in the growth crucible (4) are: Si:Cr:Cu:Al=70:20:5:

5.

8. A method for growing cylindrical silicon carbide crystals by a liquid phase method, characterized in that: Based on the device according to any one of claims 1 to 7, the method comprises: The heat dissipation control device (11) is arranged above the seed crystal (7); The positional relationship between the heat dissipation control device (11) and the seed crystal (7) is adjusted so that the silicon carbide seed crystal The crystal direction is consistent with the edge direction, and the silicon carbide seed crystal The crystal direction is consistent with the angle bisector of two adjacent edges; Start growing silicon carbide crystals by liquid phase method.

9. The method according to claim 8, characterized in that The growth temperature of liquid phase silicon carbide crystals is 1700~1900℃.

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