Apparatus and method for growing cylindrical silicon carbide single crystal by liquid phase method
By designing a heat dissipation control device with six-fold symmetry to adjust the heat dissipation rate, the problem of easy formation of hexagonal shapes in the liquid phase growth of silicon carbide single crystals was solved, realizing the efficient growth of cylindrical silicon carbide crystals and reducing processing difficulty and cost.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- BEIJING LATTICE SEMICONDUCTOR CO LTD
- Filing Date
- 2025-09-19
- Publication Date
- 2026-06-25
AI Technical Summary
When growing silicon carbide single crystals using the liquid phase method, the crystals tend to develop into hexagonal shapes, which leads to high processing difficulty, high cost, and easy cracking. Existing equipment is difficult to grow cylindrical silicon carbide crystals.
A heat dissipation control device with six-fold symmetry is adopted. By adjusting the heat dissipation rate in different crystal orientations, the crystal orientation with a fast growth rate is suppressed and the crystal orientation with a slow growth rate is promoted, so as to ensure that the crystal is cylindrical.
High-quality cylindrical silicon carbide crystal growth was achieved, reducing processing difficulty and cost, and improving crystal integrity and uniformity.
Smart Images
Figure CN2025122443_25062026_PF_FP_ABST
Abstract
Description
An apparatus and method for growing cylindrical silicon carbide single crystals by liquid phase method Technical Field
[0001] This invention relates to the field of silicon carbide single crystal preparation technology, and particularly to an apparatus and method for growing cylindrical silicon carbide single crystals by liquid phase method. Background Technology
[0002] Silicon carbide, as a typical representative of wide bandgap semiconductors, has excellent properties such as large bandgap, high breakdown field strength, high saturated electron mobility, high thermal conductivity, and good thermal and chemical stability. It is an ideal substrate material for fabricating high-frequency, high-voltage, high-efficiency, radiation-resistant, and high-temperature-resistant high-power devices and blue light-emitting diodes. This makes it a promising material for applications in new energy vehicles, high-speed rail, aerospace, high-voltage smart grids, and clean energy, and has therefore attracted widespread attention from the academic community and governments around the world.
[0003] Liquid-phase growth is an important method for preparing silicon carbide single crystals. It requires low growth temperatures, provides a relatively stable growth environment, and allows for near-equilibrium crystal growth. This not only results in relatively low growth costs but also theoretically enables higher crystal quality. Furthermore, the liquid-phase method shows promising applications in obtaining P-type substrates and crystal diameter expansion. Therefore, the liquid-phase method has received increasing attention in recent years, and related technologies have made significant breakthroughs. In the liquid-phase growth of silicon carbide single crystals, the strong anisotropy of the solid-liquid interface energy between the silicon carbide crystal and the high-temperature solution is a crucial factor. The solid-liquid interfacial energy between crystal planes and high-temperature solutions is much lower than The solid-liquid interface energy between the crystal plane family and the high-temperature solution. Therefore, when the crystal grows in the liquid phase, along... The growth rate in the direction of growth is much greater than that along the direction of growth. The directional growth rate ultimately leads to the crystal easily developing into a hexagonal shape. Hexagonal crystals are difficult and costly to process into wafers, and are prone to cracking, which can cause crystal breakage. Therefore, developing a device that can grow cylindrical SiC crystals through liquid phase is of great significance. Summary of the Invention
[0004] This invention provides an apparatus and method for growing cylindrical silicon carbide single crystals using a liquid-phase method, which can prepare cylindrical silicon carbide crystals.
[0005] In a first aspect, embodiments of the present invention provide an apparatus for growing cylindrical silicon carbide crystals using a liquid-phase method, including a heat dissipation control device mounted above a silicon carbide seed crystal.
[0006] The heat dissipation control device is thick in the middle and thin around the edges, and has an anisotropic structure with six-fold symmetry. It includes six edges with an included angle of 60° and equal length. The endpoints of each edge away from the center are connected by a concave arc towards the center, and different edges are connected by a downward concave curved surface. This makes the part where the edge is located at the same distance from the center of the heat dissipation control device have the greatest thickness and the smallest heat dissipation rate. The part where the angle bisector of two adjacent edges is located has the smallest thickness and the largest heat dissipation rate.
[0007] The heat dissipation control device is installed with a fixed correspondence to the crystal orientation of the silicon carbide seed crystal. The crystal orientation and edge direction are consistent, and the silicon carbide seed crystal has the same direction. The crystal orientation coincides with the angle bisector of the two adjacent edges.
[0008] In one possible design, the vertical projection of the arc is tangent to the vertical projection of the seed crystal.
[0009] In one possible design, a reference circle is drawn 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 the portion of 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 to 10:1. Outside the range of the reference circle, the thickness decreases to 1 to 5 mm in the direction away from the edge and away from the center of the reference circle.
[0010] In one 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 seed crystal holder is connected to the seed crystal at its lower part, and a connecting shaft is provided at the upper part of the seed crystal holder. The connecting shaft passes through a through hole at the center 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 rotate and rise synchronously under the drive of the rotating lifting rod.
[0011] In one possible design, the connecting shaft passes through a through hole in the middle of the heat dissipation control device and is snapped together with the first rotating lifting shaft. The locking sleeve is sleeved on the first rotating lifting shaft and is used to lock the snap-connection between the connecting shaft and the first rotating lifting shaft.
[0012] In one possible design, the furnace is further included and a growth crucible located inside the furnace. The furnace is equipped with an induction coil for heating. The growth crucible contains a high-temperature melt and is wrapped with insulation material. A growth crucible support plate is provided at the bottom of the crucible support plate, and a second rotating lifting shaft for lifting and rotating is provided at the bottom of the support plate.
[0013] In one possible design, the growth crucible is a graphite crucible, and the composition and ratio of the high-temperature melt inside the growth crucible are: Si:Cr:Cu:Al = 70:20:5:5.
[0014] Secondly, embodiments of the present invention also provide a method for growing cylindrical silicon carbide crystals using a liquid-phase method, based on any of the above-described apparatus, the method comprising:
[0015] The heat dissipation control device is disposed above the seed crystal;
[0016] Adjusting the positional relationship between the heat dissipation control device and the seed crystal, so that the silicon carbide seed crystal... The crystal orientation and edge direction are consistent, and the silicon carbide seed crystal has the same direction. The crystal orientation coincides with the angle bisector of two adjacent edges;
[0017] The liquid phase method was used to grow silicon carbide crystals.
[0018] In one possible design, the growth temperature of liquid-phase silicon carbide crystals 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 its growth rate varies significantly along different crystal orientations during liquid-phase growth, exhibiting significant anisotropy. This is the fundamental reason why SiC crystals readily develop into hexagonal shapes during liquid-phase growth. Based on the basic principles of crystal growth, this invention provides a heat dissipation control device with a six-fold symmetry structure. The main structural feature of the device is that it is designed with a large thickness and large size along six equivalent first characteristic directions (i.e., six edges) where the angle between them is 60 degrees. This can suppress heat dissipation. By adjusting the position of the heat dissipation control device to align it with the crystal orientation of the seed crystal in the growth rate block, the heat dissipation of SiC crystals during rapid growth can be suppressed. To suppress the heat dissipation rate of SiC crystals in the crystal direction. The growth rate in the crystal direction; in the other six second characteristic directions, which are at an angle of 30 degrees to the above six directions respectively, i.e., on the angle bisectors of adjacent edges, a structure with small thickness and small size is set. In this way, it can accelerate heat dissipation. Adjust the position of the heat dissipation control device to keep it consistent with the crystal orientation of the seed crystal with a slow growth rate, thereby accelerating the growth of SiC crystal in the slow growth direction. To accelerate the heat dissipation rate of SiC crystals in the crystal direction. The growth rate in the crystal direction. In summary, by suppressing the direction with a fast growth rate and promoting the direction with a slow growth rate, the resulting silicon carbide crystal is cylindrical. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 is a schematic diagram of the structure of an apparatus for vapor-phase growth of silicon carbide single crystals provided in an embodiment of the present invention;
[0023] Figure 2 is a schematic diagram of the installation process of a connecting column and a first rotating lifting shaft according to an embodiment of the present invention;
[0024] Figure 3 is a schematic diagram of a heat dissipation control device and the crystal orientation relationship of a seed crystal provided in an embodiment of the present invention;
[0025] Figure 4 shows the silicon carbide crystal prepared in Example 1 of the present invention;
[0026] Figure 5 shows the silicon carbide crystal prepared in Comparative Example 1 of the present invention;
[0027] Figure 6 shows the silicon carbide crystal prepared in Comparative Example 2 of this invention.
[0028] In the figure: 1-First rotating lifting shaft; 2-Growth furnace; 3-Insulation 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 shaft; 11-Heat dissipation control device; 12-Locking sleeve. Detailed Implementation
[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0030] In the description of the embodiments of the present invention, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; unless otherwise specified or stated, the term "multiple" refers to two or more; the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.
[0031] In this specification, it should be understood that the directional terms such as "upper" and "lower" used in the description of the embodiments of the present invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of the present invention. Furthermore, in the context, it should also be understood that when it is mentioned that one element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.
[0032] As shown in Figures 1 to 3, embodiments of the present invention provide an apparatus for growing cylindrical silicon carbide crystals using a liquid-phase method.
[0033] The device 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 the edges, and has an anisotropic structure with six-fold symmetry. It includes six edges with an included angle of 60° and equal length. The endpoints of each edge away from the center are connected by a concave arc towards the center. The radius of the arc is the same as the radius of the silicon carbide seed crystal 7. Different edges are connected by a downward concave curved surface. The thickness of the part where the edge is located is the largest at the same distance from the center of the heat dissipation control device 11, and the heat dissipation rate is the smallest. The thickness of the part where the angle formed by two adjacent edges is the smallest is the thinnest, and the heat dissipation rate is the largest.
[0034] The heat dissipation control device is installed with a fixed correspondence to the crystal orientation of the silicon carbide seed crystal. The crystal orientation and edge direction are consistent, and the silicon carbide seed crystal has the same direction. The crystal orientation coincides with the angle bisectors of two adjacent edges.
[0035] The crystal structure of SiC determines that its growth rate varies significantly along different crystal orientations during liquid-phase growth, exhibiting significant anisotropy. This is the fundamental reason why SiC crystals easily develop into hexagonal shapes during liquid-phase growth. Based on the basic principles of crystal growth, this invention provides a heat dissipation control device 11 with a six-fold symmetry structure. The main structural feature of the device is that it is designed with a large thickness and large size along the six equivalent first characteristic directions, i.e., the six edges, where the included angle is 60 degrees. This can suppress heat dissipation. Adjusting the position of the heat dissipation control device 11 allows it to be positioned relative to the seed crystal of the growth rate block. Maintaining consistent crystal orientation helps suppress the rapid growth of SiC crystals. To suppress the heat dissipation rate of SiC crystals in the crystal direction. The growth rate in the crystal direction; in the other six second characteristic directions, which are at an angle of 30 degrees to the above six directions respectively, i.e., on the angle bisectors of adjacent edges, a structure with small thickness and small size is set, which can accelerate heat dissipation. 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, thereby accelerating the growth of SiC crystal in the slow growth direction. To accelerate the heat dissipation rate of SiC crystals in the crystal direction. The growth rate in the crystal direction. In summary, by suppressing the direction with a fast growth rate and promoting the direction with a slow growth rate, the resulting silicon carbide crystal is cylindrical.
[0036] Specifically, the heat dissipation control device 11, which is thicker in the middle and thinner around the edges, makes the resulting silicon carbide crystal thickness more uniform. In the circumferential direction, the heat dissipation control device 11 is thicker in directions with faster growth rates, slowing down growth, while it is thinner in directions with slower growth rates, accelerating growth. To obtain silicon carbide crystals with high sphericity and uniform thickness, the thickness variation is gradual. Since the thickness in the first characteristic direction is greater than that in the second characteristic direction, it becomes thinner closer to the edge of the second characteristic direction, eventually reducing to 0, meaning the final length of the second characteristic direction is shorter than that of the first characteristic direction. It should be noted that because the circumferential thickness is gradual, the portion between the first and second characteristic directions is also gradual; that is, the length in 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 shortens. The final vertical projection of the heat dissipation control device 11 consists of six arcs.
[0037] 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 ensures that the heat dissipation rate does not change abruptly, making the change in the heat dissipation rate smoother, and can completely cover the entire seed crystal.
[0038] In some embodiments of the present invention, a reference circle is drawn 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 of 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.
[0039] In this embodiment, by setting the above parameters, the heat dissipation rate of different parts can be adjusted, ultimately resulting in a spherical silicon carbide crystal.
[0040] 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 seed crystal holder 5 is connected to a seed crystal 7 at its lower part and a connecting shaft is provided at the upper part of the seed crystal holder 5. The connecting shaft passes through a through hole at the center 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 rotate and rise synchronously under the drive of the rotating lifting rod.
[0041] In this embodiment, the detachable connecting shaft and the first rotating lifting shaft 1 can remove the seed crystal holder 5 and the silicon carbide crystal grown below it after growth is completed, so as to realize the reuse of the heat dissipation control device 11.
[0042] In some embodiments of the present invention, the connecting shaft passes through the through hole in the middle of the heat dissipation control device 11 and is snapped together with the first rotating lifting shaft 1. The locking sleeve 12 is sleeved on the first rotating lifting shaft 1 and is used to lock the snap-connection between the connecting shaft and the first rotating lifting shaft 1.
[0043] In some embodiments of the present invention, a growth furnace 2 and a growth crucible 4 located inside the growth furnace 2 are also included. An induction coil 6 for heating is provided inside the growth furnace 2. The growth crucible 4 contains a high-temperature melt 8. The growth crucible 4 is wrapped with a heat-insulating material 3. 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.
[0044] 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 inside the growth crucible 4 are: Si:Cr:Cu:Al = 70:20:5:5.
[0045] This invention also provides a method for growing cylindrical silicon carbide crystals using a liquid phase method, based on any of the above-described apparatus, the method comprising:
[0046] A heat dissipation control device 11 is installed above the seed crystal 7;
[0047] Adjusting 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 and edge direction are consistent, silicon carbide seed crystal 7 The direction is consistent with the angle bisectors of the two adjacent edges;
[0048] The liquid phase method was used to grow silicon carbide crystals.
[0049] In some embodiments of the present invention, the growth temperature of liquid-phase silicon carbide crystals is 1700–1900 °C.
[0050] This invention also provides a more specific method for growing silicon carbide crystals using a liquid-phase method:
[0051] The co-solvent raw materials are loaded into the graphite crucible according to the specified ratio;
[0052] The silicon carbide seed crystal is bonded to the seed crystal holder 5 according to specific orientation requirements, and the heat dissipation control device 11 is installed on the seed crystal holder 5. Here, it is necessary to ensure the silicon carbide seed crystal... The crystal orientation is consistent with the first characteristic direction of the heat dissipation control device 11.
[0053] Connect the seed crystal rod to the seed crystal holder 5, and then install the locking sleeve 12;
[0054] Place the 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;
[0055] Fix the seed crystal rod on the rotating lifting device of the equipment, while ensuring that the seed crystal position is higher than the raw material surface;
[0056] Close the furnace chamber and perform a vacuum process. When the furnace chamber pressure is less than or equal to 10... -4 After Pa, protective gas is introduced into the furnace cavity;
[0057] Heat the crucible to completely liquefy the fluxing agent in it, and let it stand for a period of time.
[0058] Slowly push the seed crystal down until it is in complete contact with the liquid surface, and crystal growth begins;
[0059] After crystal growth begins, the crystal growth furnace is controlled to cause the seed crystal to rotate periodically in both forward and reverse directions and be slowly pulled upwards under the drive of the seed crystal rotation and pulling shaft; the crucible is also caused to rotate periodically in both forward and reverse directions and be slowly moved upwards under the drive of the crucible rotation and pulling shaft; the rotation period of the crucible and the seed crystal are consistent and their rotation directions are always opposite.
[0060] After growth is complete, the crystals are slowly pulled off the liquid surface and then slowly cooled.
[0061] 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, heat dissipation control device 11, and seed crystal holder 5. After removing the crystal from the seed crystal holder 5, the seed crystal holder 5, heat dissipation control device 11, seed crystal rod, and locking sleeve 12 can be reused.
[0062] To more clearly illustrate the technical solution and advantages of the present invention, several embodiments are described in detail below.
[0063] Example 1
[0064] This embodiment uses the apparatus and method provided by the present invention to perform liquid-phase growth of silicon carbide single crystals. The main steps are as follows:
[0065] The growth raw materials were loaded into a graphite crucible according to the following ratio: Si:Cr:Cu:Al = 70:20:5:5, the total mass of the raw materials was 12kg, and the diameter of the crucible was 170mm.
[0066] A 6-inch diameter silicon carbide seed crystal is bonded to the seed crystal holder 5 according to specific orientation requirements, and a heat dissipation control device 11 is installed on the seed crystal holder 5, while ensuring the silicon carbide seed crystal's... The crystal orientation is consistent with the first characteristic direction of the heat dissipation control device 11.
[0067] Connect the seed crystal rod to the seed crystal holder 5, and then install the locking sleeve 12;
[0068] Place the 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;
[0069] Fix the seed crystal rod on the rotating lifting device of the equipment, while ensuring that the seed crystal position is higher than the raw material surface;
[0070] Close the furnace chamber and perform a vacuum process. When the furnace chamber pressure is less than or equal to 10... -4 After Pa, Ar protective gas is introduced into the furnace cavity;
[0071] Heating the crucible completely liquefies the fluxing agent in it, maintaining the temperature at 1900℃ and allowing it to stand for a period of time.
[0072] Slowly push the seed crystal down until it is in complete contact with the liquid surface, and crystal growth begins;
[0073] After crystal growth begins, the crystal growth furnace is controlled to cause the seed crystal to rotate periodically in both forward and reverse directions and be slowly pulled upwards under the drive of the seed crystal rotation and pulling shaft; the crucible is also caused to rotate periodically in both forward and reverse directions and be slowly moved upwards under the drive of the crucible rotation and pulling shaft; the rotation period of the crucible and the seed crystal are consistent and their rotation directions are always opposite.
[0074] After growth is complete, the crystals are slowly pulled off the liquid surface and then slowly cooled.
[0075] After the crystal has cooled to room temperature, open the furnace lid and remove the grown crystal.
[0076] Figure 4 shows a 6-inch silicon carbide crystal grown by the apparatus and method provided by the present invention. The crystal is round and the crystal growth surface is very bright, reflecting high crystal quality. This indicates that the method effectively suppresses the development of the crystal into a hexagonal shape.
[0077] Comparative Example 1
[0078] The heat dissipation control device 11 is not used; otherwise, it is the same as in Example 1.
[0079] As shown in Figure 5, the silicon carbide crystal obtained in Comparative Example 1 has a hexagonal shape with very obvious edges and corners.
[0080] Comparative Example 2
[0081] When installing the heat dissipation control device 11, the silicon carbide seed crystal is... The crystal orientation is consistent with the second characteristic direction of the heat dissipation control device 11, which is exactly the opposite of the installation method required by the present invention, while other processes remain unchanged.
[0082] As shown in Figure 6, the six corners of the crystal obtained in Comparative Example 2 are still very obvious. In addition, the six sides show obvious signs of shrinking inward. Therefore, not following the assembly method provided by the present invention will not only fail to eliminate the hexagons, but will also lead to a reduction in the crystal diameter. The reduction in diameter will make it impossible to process wafers of standard size.
[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. An apparatus for growing cylindrical silicon carbide crystals by liquid phase method, characterized in that, The device 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 the edges, and has an anisotropic structure with six-fold symmetry. It includes six edges with an included angle of 60° and equal length. The endpoints of each edge away from the center are connected by a concave arc towards the center. Different edges are connected by a downward concave curved surface. The thickness of the part where the edge is located is the largest and the heat dissipation rate is the smallest at the same distance from the center of the heat dissipation control device (11). The thickness of the part where the angle 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 is installed with a fixed correspondence to the crystal orientation of the silicon carbide seed crystal. The crystal orientation and edge direction are consistent, and the silicon carbide seed crystal has the same direction. The crystal orientation coincides with the angle bisector of the two adjacent edges.
2. The apparatus according to claim 1, characterized in that, The vertical projection of the arc is tangent to the vertical projection of the seed crystal (7).
3. The apparatus according to claim 1, characterized in that, A reference circle is drawn 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 of the same length from the axis of the heat dissipation control device (11), the thickness ratio 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 the direction away from the edge and away from the center of the reference circle.
4. The apparatus 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). The first rotating lifting shaft (1) is used for lifting and rotating. The seed crystal holder (5) is connected to the seed crystal (7) at its lower part. A connecting shaft is provided on the upper part of the seed crystal holder (5). The connecting shaft passes through the through hole at the center 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 rotate and lift synchronously under the drive of the rotating lifting rod.
5. The apparatus according to claim 4, characterized in that, The connecting shaft passes through the through hole in the middle of the heat dissipation control device (11) and is snapped together with the first rotating lifting shaft (1). The locking sleeve (12) is sleeved on the first rotating lifting shaft (1) and is used to lock the snap-connection between the connecting shaft and the first rotating lifting shaft (1).
6. The apparatus according to claim 1, characterized in that, It also includes a growth furnace (2) and a growth crucible (4) located inside the growth furnace (2). The growth furnace (2) is equipped with an induction coil (6) for heating. The growth crucible (4) is filled with high-temperature melt (8). The growth crucible (4) is wrapped with 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).
7. The apparatus according to claim 6, characterized in that, 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.
8. A method for growing cylindrical silicon carbide crystals using a liquid-phase method, characterized in that, Based on the apparatus of any one of claims 1-7, the method comprises: The heat dissipation control device (11) is provided above the seed crystal (7); Adjust the positional relationship between the heat dissipation control device (11) and the seed crystal (7) so that the silicon carbide seed crystal... The crystal orientation and edge direction are consistent, and the silicon carbide seed crystal has the same direction. The crystal orientation coincides with the angle bisector of two adjacent edges; The liquid phase method was used to grow silicon carbide crystals.
9. The method according to claim 8, characterized in that, The growth temperature of silicon carbide crystals by liquid phase method is 1700-1900℃.