Apparatus for growing silicon carbide single crystal by using liquid phase method, and growth method

Abstract

The present invention belongs to the technical field of silicon carbide single crystal production, and relates to an apparatus for growing a silicon carbide single crystal by using a liquid phase method, and a growth method. The growth apparatus comprises a growth crucible, a seed rod on which a seed crystal is fixed, a laser rangefinder for measuring the position of growth starting materials, a movable graphite block, a braking apparatus, and sealing graphite. A reserved hole is provided directly below a light-emitting hole of the corresponding laser rangefinder on a crucible lid of the growth crucible. A side wall of the growth crucible is provided with at least four rows of holes, each row of holes is evenly distributed from top to bottom, and a hole is provided at a bottom center position. The movable graphite block fills a hole, one end of the sealing graphite is embedded in a hole, and the other end is sleeved on an outer wall of the growth crucible. The center of the sealing graphite is provided with an opening through which the braking apparatus passes and connects to the movable graphite block. The braking apparatus is used to control the forward and backward movement of the movable graphite block relative to the growth starting materials. The apparatus of the present invention can achieve the determination and adjustment of a high-temperature line position before crystal growth, reduce self-circulating convection in growth solutions, and improve carbon utilization.

Description

A liquid-phase silicon carbide single crystal growth apparatus and growth method Technical Field

[0001] This invention belongs to the field of silicon carbide single crystal production technology, and particularly relates to a liquid-phase silicon carbide single crystal growth apparatus and growth method. Background Technology

[0002] Silicon carbide (SiC) is one of the most important third-generation semiconductor materials. Its unique characteristics, such as a large bandgap and high critical breakdown field strength, make it an ideal material for manufacturing high-frequency, high-power, radiation-resistant, and photoelectric integrated devices. It is currently widely used in many fields, including new energy vehicles, 5G communications, and aerospace. The high price of silicon carbide substrate wafers in the market is mainly due to the high production cost and low yield of silicon carbide single crystals, resulting in a supply shortage.

[0003] As one of the methods for growing silicon carbide single crystals, the liquid phase method places great importance on determining the high-temperature line and ensuring a stable supply of carbon source. However, in liquid phase silicon carbide single crystal growth, whether the high-temperature line is located at the intended position can only be determined experimentally by cutting open the growth crucible. This is because the melting rate is fastest at the high-temperature line. By observing the melting of the growth crucible after the experiment, the position of the high-temperature line can be determined. However, this discrepancy can lead to the current batch of experiments not proceeding as expected, resulting in wasted resources. Furthermore, the high-temperature line can shift over multiple batches of experiments. If the position of the high-temperature line is not confirmed before the start of each batch of crystal growth, misalignment of the high-temperature line can lead to experimental errors, resulting in a large product error rate.

[0004] In the liquid-phase growth of silicon carbide single crystals, the carbon source in the solution is transported by convection. However, existing technology shows (see: Minh-Tan Ha, et al. "Flow modification enhancing the growth rate in top seeded solution growth of SiC crystals." RSC Advances 9.) that a partial self-circulating convection region exists in the solution during the liquid-phase growth of silicon carbide single crystals. This region affects the carbon source supply, reduces the carbon utilization rate, and results in insufficient utilization of the carbon source.

[0005] Therefore, it is essential to provide a liquid-phase silicon carbide single crystal growth apparatus and method that can determine and adjust the position of the high-temperature line before crystal growth and reduce self-circulating convection in the crystal growth solution. Summary of the Invention

[0006] To address one or more technical problems existing in the prior art, this invention provides a liquid-phase silicon carbide single crystal growth apparatus and method. The growth apparatus and method of this invention can reduce the self-circulating convection region within the crucible, improve carbon source utilization, and ensure experimental accuracy by confirming and adjusting the relative positions of the high-temperature lines before crystal growth.

[0007] The present invention provides a liquid-phase silicon carbide single crystal growth apparatus in a first aspect. The apparatus includes a growth crucible for holding growth materials, a seed crystal rod with a seed crystal fixed thereon, a laser rangefinder for determining the position of the growth materials, a movable graphite block, a braking device, and sealing graphite. The growth crucible includes a crucible body and a crucible lid. A pre-drilled hole is provided on the crucible lid, located directly below the light-emitting aperture of the laser rangefinder. Multiple holes are provided on the sidewall of the growth crucible, and these holes are evenly spaced on the sidewall. The growth crucible is arranged in at least four columns from the ground, with holes evenly distributed from top to bottom in each column. A hole is opened at the center of the bottom of the growth crucible, and the movable graphite block is filled in the hole. One end of the sealing graphite is embedded in the hole, and the other end is sleeved on the outer wall of the growth crucible. An opening is opened in the center of the sealing graphite for the braking device to pass through. The braking device passes through the opening and is connected to the movable graphite block. The braking device is used to control the movable graphite block to move back and forth relative to the growth material.

[0008] Preferably, the sidewall of the growth crucible has multiple holes extending from near the surface of the growth raw material liquid to near the bottom of the growth crucible; each row contains at least two holes.

[0009] Preferably, a recessed hole is provided at the position where the movable graphite block is connected to the braking device, and one end of the braking device is engaged in the recessed hole; the other end of the braking device is connected to a servo motor.

[0010] Preferably, the crucible lid has an opening at its center, and the end of the seed crystal rod with the seed crystal fixed thereon extends into the interior of the crucible body through the opening; the end of the seed crystal rod without the seed crystal fixed thereon is connected to a transmission device, which is used to control the lifting and rotating of the seed crystal rod.

[0011] Preferably, the hole is a cylindrical hole with a diameter of 5 to 40 mm.

[0012] Preferably, the hole is a fan-shaped annular hole, and the angle of the fan-shaped annular hole is 30° to 90°.

[0013] Preferably, the sidewall thickness and / or bottom thickness of the growth crucible is 10-40 mm; and / or the movable graphite block is connected to the hole of the growth crucible by a threaded connection or a slot connection.

[0014] Preferably, the outer side of one end of the sealing graphite embedded in the hole is provided with a silicon carbide coating; and / or the growth raw material includes Si and a fluxing agent X, wherein the fluxing agent X is one or more of Al, B, Ti, Cr, Fe, Y, Yb, Pr, La, Cu, Ag, Nd, Ce, Sn, Ge, and Co.

[0015] In a second aspect, the present invention provides a method for growing silicon carbide single crystals using a liquid-phase method. The method employs the liquid-phase silicon carbide single crystal growth apparatus described in the first aspect of the present invention, and includes the following steps:

[0016] (1) The growth material is placed in the crucible body of the growth crucible and heated to melt the growth material into a liquid state;

[0017] (2) The movable graphite block filled in the hole at the center of the bottom of the growth crucible is pushed into the liquid growth material by the braking device. The pushing distance is 3 / 4 of the bottom thickness of the growth crucible. The difference in distance between the growth material and the laser rangefinder before and after the movable graphite block is pushed in is measured by the laser rangefinder as Δh. After measuring the distance difference Δh, the movable graphite block is pulled back to its original position.

[0018] (3) The movable graphite blocks filled in a row of holes on the side wall of the growth crucible are pushed into the liquid growth material from top to bottom through the braking device. The pushing distance is 3 / 4 of the thickness of the side wall of the growth crucible. The distance difference between the growth material and the laser rangefinder is measured before and after each movable graphite block is pushed in. After measuring the distance difference corresponding to each movable graphite block, the corresponding movable graphite block is pulled back to its original position before the next movable graphite block is pushed in.

[0019] (4) Compare the distance difference corresponding to each active graphite block with Δh. The position of the active graphite block with the smallest distance difference is the position of the high temperature line. If the determined high temperature line position is inconsistent with the set high temperature line position, adjust the high temperature line position to be consistent with the set high temperature line position by moving the growth crucible.

[0020] (5) After the operation in step (4) is completed, the seed crystal fixed on the seed crystal rod is lowered to contact the liquid growth material surface to grow silicon carbide single crystal and obtain silicon carbide single crystal; during the growth of silicon carbide single crystal, at least the movable graphite blocks on the side wall of the growth crucible near the liquid growth material surface and near the bottom of the growth crucible are moved back and forth relative to the growth material by the braking device.

[0021] Preferably, in step (5), the number of forward and backward movements is controlled to be 10 to 15 times / min.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] (1) This invention provides a growth apparatus for liquid-phase silicon carbide single crystals. By improving the growth crucible, setting movable graphite blocks in the growth crucible, sealing graphite, and adding a braking device, the high-temperature line position can be confirmed before the start of crystal growth, so as to ensure timely adjustment of the high-temperature line position. This helps to reduce experimental errors caused by high-temperature line misalignment and reduce the product error rate. It solves the problem that in the existing liquid-phase silicon carbide single crystal growth, whether the high-temperature line is in the set position can only be known after experimentation, which will lead to the current batch of experiments not being able to be carried out as expected, resulting in resource waste.

[0024] (2) The liquid phase silicon carbide single crystal growth device provided by the present invention can fully agitate the solution, reduce the self-circulation convection inside the solution, improve the carbon utilization rate, thereby helping to reduce the density of crystal inclusions, and solves the problem that in the existing liquid phase silicon carbide single crystal growth, there is partial self-circulation convection in the solution, which leads to insufficient utilization of carbon source.

[0025] (3) The present invention also proposes a growth method based on the liquid phase silicon carbide single crystal growth device. This growth method can realize the confirmation and adjustment of the high temperature line before crystal growth and can effectively reduce self-circulation convection and improve carbon utilization during crystal growth. In addition, the liquid phase silicon carbide single crystal growth method in the present invention can quantitatively judge the melting situation at the high temperature line and carry out emergency treatment of possible leakage. This solves the problem that the growth raw material may leak because the melting rate at the high temperature line is the fastest and the high temperature line position is not adjusted in time or the crystal is not pulled out for cooling in time. Attached Figure Description

[0026] The accompanying drawings are provided for illustrative purposes only, and the proportions, sizes, and quantities of the parts in the drawings may not necessarily match the actual product.

[0027] Figure 1 is a schematic diagram of the structure of the liquid phase silicon carbide single crystal growth apparatus provided in some specific embodiments of the present invention;

[0028] In the figure: 1: Growth crucible; 1-1: Crucible lid; 2: Seed crystal rod; 3: Laser rangefinder; 4: Movable graphite block; 5: Braking device; 6: Sealing graphite; 7: Pre-drilled hole; 8: Growth raw material. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments thereof. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0030] The present invention provides, in a first aspect, a liquid-phase silicon carbide single crystal growth apparatus (hereinafter referred to as a growth apparatus), for example, as shown in FIG1, the growth apparatus includes a growth crucible 1 for holding growth material 8, a seed crystal rod 2 with a seed crystal fixed thereon, a laser rangefinder 3 for measuring the position of the growth material, a movable graphite block 4, a braking device 5, and a sealing graphite 6; in the present invention, the laser rangefinder 3 can monitor the liquid level of the growth material in real time, thereby determining the degree of crucible erosion; the growth crucible 1 is a container for crystal growth, the growth crucible 1 includes a crucible body and a crucible lid 1-1, the crucible body and the crucible lid 1-1 being connected, for example, by a threaded connection, the growth material 8 being held inside the crucible body, and so on. A pre-drilled hole 7 is provided on the crucible lid 1-1. The pre-drilled hole 7 is located directly below the light output hole of the laser rangefinder 3, allowing the laser rangefinder 3 to penetrate vertically into the growth crucible 1 through the pre-drilled hole 7, accurately measuring the distance between the growth material and the laser rangefinder, thereby determining the position of the growth material liquid surface. Multiple holes are provided on the sidewall (circumferential direction) of the growth crucible 1. These holes are arranged in at least four rows at equal intervals along the sidewall (height direction), with each row containing holes evenly distributed from top to bottom. A hole is provided at the center of the bottom of the growth crucible 1. The movable graphite block 4 fills this hole, and one end of the sealing graphite 6 is embedded in the hole, while the other end is fitted onto the... On the outer wall of the growth crucible 1, the sealing graphite 6 is used to seal the movable graphite block 4 to the external pores, preventing the growth material 8 from flowing out. In this invention, the number of pores, the number of movable graphite blocks, the number of braking devices, and the number of sealing graphite are all the same, that is, one pore corresponds to one movable graphite block 4 and one sealing graphite 6, and one movable graphite block 4 corresponds to one braking device 5. The sealing graphite 6 has an opening in its center for the braking device 5 to pass through. The braking device 5 passes through the opening and is connected to the movable graphite block 4. The braking device 5 is used to control the movable graphite block 4 to move back and forth relative to the growth material 8, and the braking device provides the movable graphite block with a driving force. The force allows it to move back and forth; the invention does not specifically limit the structure of the braking device 5, as long as it can be used to control the movement of the movable graphite block relative to the growth material; in the invention, when assembling the liquid phase silicon carbide single crystal growth apparatus, the movable graphite block 4 is first screwed into the hole, then the sealing graphite 6 is embedded in the hole and fitted onto the outer wall of the growth crucible 1, and then the braking device 5 is connected to the movable graphite block 4 through the opening of the sealing graphite 6; in the invention, the movable graphite block fills the hole in the growth crucible, which can provide a carbon source for crystal growth, and the braking device can control its movement back and forth relative to the growth material to agitate the growth material solution and reduce convection self-circulation.

[0031] The liquid-phase silicon carbide single crystal growth apparatus of this invention improves the growth crucible by incorporating movable graphite blocks, sealing graphite, and adding a braking device. This allows for confirmation of the high-temperature line position before crystal growth begins, ensuring timely adjustment and reducing experimental errors caused by high-temperature line misalignment. It also lowers the product error rate and solves the problem in existing liquid-phase silicon carbide single crystal growth methods where the position of the high-temperature line can only be determined experimentally, leading to unintended experiments and wasted resources. Furthermore, the liquid-phase silicon carbide single crystal growth apparatus provided by this invention can fully agitate the solution, reducing internal self-circulation convection and improving carbon utilization. This helps reduce the inclusion density in the crystal, addressing the problem of insufficient carbon source utilization caused by partial self-circulation convection in existing liquid-phase silicon carbide single crystal growth methods.

[0032] According to some preferred embodiments, the sidewall of the growth crucible 1 is provided with multiple holes from near the surface of the growth raw material liquid to near the bottom of the growth crucible 1, that is, multiple holes are provided from near the surface of the growth raw material liquid of the growth crucible 1 downwards; each row contains at least two holes.

[0033] According to some preferred embodiments, a recess is provided at the position where the movable graphite block 4 is connected to the braking device 5, and one end of the braking device 5 is engaged in the recess; the other end of the braking device 5 is connected to a servo motor (not shown in the figure).

[0034] According to some preferred embodiments, the liquid-phase silicon carbide single crystal growth apparatus further includes an induction heating device for heating. The induction heating device includes an induction coil (also referred to as a heating coil), which is coaxially arranged with the seed crystal rod 2. The induction heating device heats the growth crucible through electromagnetic induction. In this invention, when the induction heating device is also included, the other end of the braking device can, for example, pass through the induction coil of the induction heating device and be connected to the servo motor.

[0035] According to some preferred embodiments, the liquid-phase silicon carbide single crystal growth apparatus further includes a heat insulation layer (not shown in the figure) disposed on the outside of the growth crucible 1. An induction heating device (not shown in the figure) for heating is disposed on the outside of the heat insulation layer. The induction heating device includes an induction coil (also referred to as a heating coil), which is coaxially arranged with the seed crystal rod 2. The induction heating device heats the growth crucible 1 through electromagnetic induction. In this invention, when the liquid-phase silicon carbide single crystal growth apparatus further includes the induction heating device and the heat insulation layer, a braking device connected to the movable graphite block filled in the holes in the side wall of the growth crucible is included. The other end of the braking device passes through the insulation layer located on the outer sidewall and the outer bottom of the growth crucible and is connected to the servo motor. The distance the braking device passes through in the insulation layer located on the outer sidewall of the growth crucible and the width of the area it passes through in the insulation layer located on the outer bottom of the growth crucible are both greater than the distance the movable graphite block moves back and forth relative to the growth material. The other end of the braking device connected to the movable graphite block filled in the hole at the center of the bottom of the growth crucible passes through the insulation layer located on the outer bottom of the growth crucible and is connected to the servo motor. In this invention, the insulation layer can be spliced ​​and laid on the outer side of the growth crucible in a layered manner, for example.

[0036] According to some preferred embodiments, the crucible cover 1-1 has an opening at its center, and the end of the seed crystal rod 2 with the seed crystal fixed thereon extends into the interior of the crucible body through the opening. In this invention, the reserved hole 7 on the crucible cover 1-1 can be located at any position on the crucible cover except for the opening. The end of the seed crystal rod 2 without the seed crystal fixed thereon is connected to a transmission device (not shown in the figure). The transmission device is used to control the lifting and rotation of the seed crystal rod 2, and provides power for the lifting and rotation of the seed crystal. This invention does not specifically limit the transmission device; it is a conventional design in the art, and it can be used to control the lifting and rotation of the seed crystal rod. In this invention, the liquid phase silicon carbide growth apparatus may also include, for example, a crucible transmission device (not shown in the figure) for rotating and lifting the growth crucible 1. This invention also does not specifically limit the setting of the crucible transmission device; it can adopt a conventional setting in the art.

[0037] According to some specific embodiments, the seed crystal is fixed to the seed crystal rod 2 by a seed crystal holder. The upper end of the seed crystal rod 2 is connected to a transmission device, which can drive the seed crystal rod to rise, fall, and rotate. The lower end of the seed crystal rod is connected to the seed crystal holder that bonds the seed crystal. The seed crystal is located at the bottom. As the seed crystal rod descends, the seed crystal first contacts the surface of the growth raw material liquid. In this invention, preferably, the seed crystal holder is made of high-purity graphite material (graphite content, for example, ≥99.9995wt%) or high-purity silicon carbide material (silicon carbide content, for example, ≥99.995wt%). The seed crystal is pasted to the front of the seed crystal holder with an adhesive.

[0038] According to some preferred embodiments, the holes are cylindrical holes with a diameter of 5–40 mm (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40 mm); on the sidewall of the growth crucible of the present invention, the number of holes in each row is at least two, and in each row of holes… The distance between two adjacent holes can be selected as needed, preferably 5 to 20 mm. That is, on the side wall of the growth crucible, in each row of movable graphite blocks, the distance between two adjacent movable graphite blocks is preferably 5 to 20 mm. The distance between two adjacent movable graphite blocks in each row on the side wall of the growth crucible determines the density of the movable graphite blocks in the row. The accuracy of the high temperature line determination can be determined by the density of the movable graphite blocks in the row. The diameter of the cylindrical holes can be selected based on the accuracy of the high temperature line determination.

[0039] According to some preferred embodiments, the hole is a fan-shaped annular hole, and the angle of the fan-shaped annular hole is 30° to 90° (e.g., 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85° or 90°).

[0040] According to some preferred embodiments, the sidewall thickness and / or bottom thickness of the growth crucible 1 is 10-40 mm. In this invention, the sidewall thickness and bottom thickness of the growth crucible 1 can be the same or different; and / or the movable graphite block 4 is connected to the hole of the growth crucible 1 by a threaded connection or a slot connection. In this invention, when a threaded connection is used, it is preferred that the pitch is M2 fine thread pitch, so as to ensure that the gap of the threaded connection is as small as possible. When a slot connection is used, it is necessary to minimize the error in matching the movable graphite block with the hole of the growth crucible. In this invention, when a slot connection is used, it is preferred that the movable graphite block is connected to the hole of the growth crucible by a threaded connection. Applying a silicon carbide coating to the joint helps reduce the wear and tear from graphite friction. This invention does not specifically limit the speed at which the braking device moves the movable graphite block. When the movable graphite block is connected to the hole in the growth crucible via a threaded connection, the speed at which the braking device moves the movable graphite block can be selected within a rotational speed range of 0.1 to 300 rpm. When the movable graphite block is connected to the hole in the growth crucible via a slotted connection, the speed at which the braking device moves the movable graphite block can be selected within a lifting speed range of 0.1 to 50 mm / min, but preferably, the number of forward and backward movements is controlled to be 10 to 15 times / min.

[0041] According to some preferred embodiments, the thickness of the movable graphite block 4 located on the side wall of the growth crucible 1 is not less than 9 / 10 of the side wall thickness of the growth crucible 1, but less than the side wall thickness of the growth crucible 1.

[0042] According to some preferred embodiments, the thickness of the movable graphite block 4 located at the center of the bottom of the growth crucible 1 is not less than 9 / 10 of the bottom thickness of the growth crucible 1, but less than the bottom thickness of the growth crucible 1.

[0043] According to some preferred embodiments, the diameter of one end of the sealing graphite 6 embedded in the hole matches the diameter of the hole, with an error of, for example, no more than 0.02 mm. This helps to ensure that the sealing graphite is perfectly fitted into the hole and sleeved on the outer wall of the growth crucible, so as to effectively prevent the growth raw material from flowing out.

[0044] According to some preferred embodiments, the braking device 5 includes a braking device connecting rod, which passes through the opening and connects to the movable graphite block. Preferably, the braking device connecting rod is made of high-temperature resistant insulating ceramic material. The present invention does not specifically limit the high-temperature resistant insulating material, as long as it can prevent the braking device connecting rod from being melted and heated by induction. In the present invention, for example, the braking device connecting rod passes through the opening and is engaged in the recess of the movable graphite block.

[0045] According to some preferred embodiments, the diameter of the braking device connecting rod is 1 to 10 mm.

[0046] According to some preferred embodiments, the movable graphite block 4, the sealing graphite 6, and the growth crucible 1 are made of the same material.

[0047] According to some preferred embodiments, the portion of the movable graphite block 4 near the inner wall of the growth crucible 1 is made of the same material as the growth crucible 1 (the density of the graphite used in the growth crucible is, for example, 1.8 g / cm³). 3 Similarly, the portion of the movable graphite block 4 away from the inner wall of the growth crucible 1 is made of, for example, high-density graphite (e.g., with a density of not less than 1.85 g / cm³). 3 The high-density graphite is used, which is more conducive to ensuring that the movable graphite block is not melted through. In this invention, the movable graphite block can be spliced ​​together, for example, from graphite blocks of different densities. Specifically, for example, it can be spliced ​​together from two or three graphite blocks of different densities. When three graphite blocks of different densities are spliced ​​together, the density of the three graphite blocks from the inner wall to the outer wall of the growth crucible can be, for example, 1.8 g / cm³. 3 1.85g / cm 3 and 1.91 g / cm 3 The thickness ratio of graphite blocks of the three densities can be, for example, 5:3:1.

[0048] According to some preferred embodiments, a silicon carbide coating is provided on the outer side of one end of the sealing graphite 6 embedded in the hole, which helps to prevent the sealing graphite from being melted by the growth raw material solution.

[0049] According to some preferred embodiments, the growth raw material 8 comprises Si and a fluxing material X, wherein the fluxing material X is one or more of Al, B, Ti, Cr, Fe, Y, Yb, Pr, La, Cu, Ag, Nd, Ce, Sn, Ge, and Co.

[0050] According to some preferred embodiments, the ranging accuracy of the laser rangefinder 3 is 0.01 mm.

[0051] In a second aspect, the present invention provides a method for growing silicon carbide single crystals using a liquid-phase method. The method employs the liquid-phase silicon carbide single crystal growth apparatus described in the first aspect of the present invention, and includes the following steps:

[0052] (1) The growth material 8 is placed in the crucible body of the growth crucible 1 and heated to melt the growth material 8 into a liquid state. In this invention, it is preferable to first perform a vacuum operation on the growth crucible containing the growth material and then heat it. The heating temperature is 30-50°C higher than the melting point of the growth material, so that the growth material melts into a liquid state. When performing silicon carbide single crystal growth, the growth crucible is located in the single crystal growth furnace.

[0053] (2) The movable graphite block 4, which is filled in the hole at the bottom center of the growth crucible 1, is pushed into the liquid growth material 8 (also referred to as the growth material solution) by the braking device 5. The pushing distance is 3 / 4 of the bottom thickness of the growth crucible 1. The distance difference between the growth material 8 and the laser rangefinder 3 before and after the movable graphite block 4 is pushed in is measured by the laser rangefinder 3 as Δh. After measuring the distance difference Δh, the movable graphite block 4 is pulled back to its original position. Specifically, the distances between the growth material and the laser rangefinder at the bottom center of the growth crucible are recorded as h1 and h2 before and after the movable graphite block is pushed in, respectively, and the distance difference Δh = h1 - h2 is obtained. In this invention, during the crystal growth process, the bottom center region of the growth crucible 1 is the lowest temperature point of growth. The melting of the growth crucible is minimal at this point. In this invention, it can be considered that this point is insoluble, and the distance difference Δh measured at this point can be used as a reference point.

[0054] (3) Movable graphite blocks 4, which are filled in a row of holes on the side wall of the growth crucible 1, are pushed into the liquid growth material 8 from top to bottom by a braking device 5. The pushing distance is 3 / 4 of the side wall thickness of the growth crucible 1. The distance difference between the growth material 8 and the laser rangefinder 3 before and after each movable graphite block 4 is pushed in is measured by a laser rangefinder 3. In step (3), after measuring the distance difference corresponding to each movable graphite block 4, the corresponding movable graphite block 4 is pulled back to its original position before the next movable graphite block 4 is pushed in. In this invention, when the number of holes in a row of holes on the side wall of the growth crucible is n (n≥2), each movable graphite block filled in the row of holes is pushed into the liquid growth material from top to bottom. The distance difference between the growth material and the laser rangefinder before and after each movable graphite block is pushed in is measured by a laser rangefinder and can be recorded as Δh1 until Δh is reached. n ;

[0055] (4) Compare the distance difference corresponding to each movable graphite block 4 with Δh. The position of the movable graphite block 4 with the smallest distance difference is the location of the high-temperature line. If the determined high-temperature line position is inconsistent with the set high-temperature line position, adjust the high-temperature line position to be consistent with the set high-temperature line position by moving the growth crucible 1 (by moving the growth crucible 1 in the height direction) to ensure the accuracy of the experiment. If the determined high-temperature line position is consistent with the set high-temperature line position, there is no need to adjust the position of the growth crucible 1. In step (4), for example, Δh1 up to Δh n All are compared with △h to obtain the minimum distance difference. Because the smaller the distance difference, the greater the erosion of the crucible wall. Therefore, the location of the high temperature line can be determined by finding the position of the movable graphite block corresponding to the minimum distance difference.

[0056] (5) After the operation in step (4) is completed, the seed crystal fixed on the seed crystal rod 2 is lowered to contact the liquid surface of the liquid growth material 8 to grow silicon carbide single crystal, thereby obtaining silicon carbide single crystal; during the growth of silicon carbide single crystal, at least the movable graphite blocks 4 on the side wall (circumferential direction) of the growth crucible 1 near the liquid surface of the growth material 8 and near the bottom of the growth crucible 1 are moved back and forth relative to the growth material 8 by the braking device 5, so as to ensure that the self-circulating convection at these two places is broken and the carbon utilization rate during the crystal growth process is improved; in this invention, at least the growth crucible side wall (circumferential direction) is moved back and forth relative to the growth material 8 by the braking device 5, thereby ensuring that the self-circulating convection at these two places is broken and the carbon utilization rate during the crystal growth process is improved; The movable graphite blocks on the wall near the surface of the growth material liquid and near the bottom of the growth crucible are moved back and forth relative to the growth material by a braking device. This is because during the crystal growth process, there is self-circulating convection mainly at the surface of the growth material liquid and the bottom of the growth crucible. Of course, in this invention, movable graphite blocks located at other positions around the side wall of the growth crucible can also be moved back and forth relative to the growth material by a braking device. In this invention, after the crystal growth is completed, the growth material is cooled with the furnace, the connection between the braking device and the movable graphite blocks is removed, and the growth crucible is taken out.

[0057] The growth method of the present invention can realize the confirmation and adjustment of the high-temperature line before crystal growth and can effectively reduce self-circulation convection and improve carbon utilization during crystal growth. In addition, the liquid phase silicon carbide single crystal growth method of the present invention can quantitatively judge the melting and corrosion situation at the high-temperature line, and carry out emergency treatment of possible leakage. It solves the problem that the growth raw material leakage may occur due to the fastest melting rate at the high-temperature line, the failure to adjust the position of the high-temperature line in time, or the failure to pull out the crystal for cooling in time.

[0058] According to some preferred embodiments, in step (5), the number of forward and backward movements is controlled to be 10 to 15 times / min (e.g., 10, 11, 12, 13, 14 or 15 times / min).

[0059] The present invention will be further described below by way of examples, but the scope of protection of the present invention is not limited to these embodiments.

[0060] Example 1

[0061] This embodiment provides a liquid-phase silicon carbide single crystal growth apparatus. The growth apparatus includes a growth crucible for holding growth raw materials, a seed crystal rod with a fixed seed crystal, a laser rangefinder for determining the position of the growth raw materials, a movable graphite block, a braking device, and sealing graphite. The growth crucible includes a crucible body and a crucible lid, which are connected by a threaded connection. The growth raw materials are contained in the crucible body. The crucible lid has an opening in the center. One end (lower end) of the seed crystal rod with the seed crystal fixed to it extends into the interior of the crucible body through the opening. The lower end of the seed crystal rod is connected to a seed crystal holder for bonding the seed crystal. The seed crystal is located at the bottom, and the seed crystal rod is not fixed. A transmission device is connected to one end (upper end) where the seed crystal is attached. This transmission device controls the lifting and rotation of the seed crystal rod. A pre-drilled hole is provided on the crucible cover. This hole is located directly below the light-emitting hole of the laser rangefinder, allowing the laser rangefinder to penetrate vertically into the growth crucible through the pre-drilled hole. This allows for accurate measurement of the distance between the growth material and the laser rangefinder, thus determining the position of the growth material liquid surface. Multiple holes are formed on the side wall of the growth crucible from near the growth material liquid surface to near the bottom of the crucible. These holes are arranged in eight equally spaced columns on the side wall of the growth crucible. Each column contains holes evenly distributed from top to bottom. In each column, adjacent holes... The distance between the centers of the two holes is 12mm. A hole is formed at the center of the bottom of the growth crucible. The movable graphite block fills the hole. One end of the sealing graphite is embedded in the hole, and the other end is fitted onto the outer wall of the growth crucible. The sealing graphite is used to seal the movable graphite block from the external pores, preventing the growth material from flowing out. The number of holes, the number of movable graphite blocks, the number of braking devices, and the number of sealing graphite blocks are all the same. An opening is formed in the center of the sealing graphite block for the braking device to pass through. The braking device passes through the opening and connects to the movable graphite block. The braking device is used to control the movable graphite block. The graphite block moves back and forth relative to the growth material. A recess is provided at the position where the movable graphite block is connected to the braking device. One end of the braking device is engaged in the recess, and the other end of the braking device is connected to a servo motor. The liquid-phase silicon carbide single crystal growth apparatus also includes a heat insulation layer disposed on the outside of the growth crucible. An induction heating device for heating is disposed on the outside of the heat insulation layer. The induction heating device includes an induction coil, which is coaxially disposed with the seed crystal rod. The induction heating device heats the growth crucible through electromagnetic induction. The liquid-phase silicon carbide growth apparatus also includes a crucible transmission device for rotating and lifting the growth crucible.

[0062] In this embodiment, the inner diameter of the growth crucible is 150 mm, and the thickness of the side wall and the bottom of the growth crucible are both 20 mm. The holes opened in the side wall and the bottom of the growth crucible are cylindrical holes. The movable graphite block filled in is a cylindrical graphite column with a diameter of 10 mm and a thickness (height) of 18 mm. The braking device includes a braking device connecting rod, which passes through the opening and is engaged in the concave hole of the movable graphite block. The braking device connecting rod is a high-temperature resistant insulating ceramic column with a diameter of 2 mm.

[0063] This embodiment also provides a method for growing silicon carbide single crystals using a liquid phase method, which is performed using the liquid phase silicon carbide single crystal growth apparatus described in this embodiment, and includes the following steps:

[0064] ① Heating stage: The growth material is placed in the crucible body of the growth crucible, the furnace is evacuated, and then argon gas is introduced as a protective gas. Then the power is turned on to raise the temperature to 40°C above the melting point of the growth material, so that the growth material in the growth crucible melts into a liquid state. The growth material used in this embodiment is a mixture of Si, Cr and Al. In the growth material, the mass percentage of these three components is Si: 50%, Cr: 48%, and Al: 2%.

[0065] ② Crystal growth stage: The seed crystal fixed on the seed crystal rod is lowered to contact the liquid growth material surface to grow silicon carbide single crystals. During the crystal growth stage, the rotation of the seed crystal and the growth crucible is controlled to ensure uniform composition of the growth material solution. At the same time, the rise or fall of the seed crystal and the growth crucible is controlled to ensure a stable liquid level height for the crystal and a suitable growth environment. In addition, during the crystal growth stage, the movable graphite blocks on the side wall of the growth crucible near the growth material surface and near the bottom of the growth crucible are moved back and forth relative to the growth material by a braking device. The number of times the movable graphite blocks move back and forth is controlled to be 12 times / min, thereby reducing self-circulation convection and improving carbon utilization.

[0066] ③ Cooling and crystal removal stage: After growth is completed, the seed crystal is pulled out of the growth raw material solution. Then the power is reduced to 0kW to stop the seed crystal and the growth crucible from rotating and the moving graphite block from moving back and forth. After the growth raw material is cooled with the furnace, the growth crucible is taken out from the single crystal growth furnace and the obtained silicon carbide single crystal is taken out to obtain silicon carbide single crystal.

[0067] The liquid-phase silicon carbide single crystal growth apparatus described in this embodiment is used for silicon carbide single crystal growth. This reduces self-circulation convection during crystal growth, improves carbon utilization, and thus enhances crystal quality, resulting in an inclusion density of as low as 7 inclusions / cm³. 3 the following.

[0068] Example 2

[0069] This embodiment provides a liquid-phase silicon carbide single crystal growth apparatus, the structure of which is the same as that in Embodiment 1.

[0070] This embodiment also provides a method for growing silicon carbide single crystals using a liquid phase method, which is performed using the liquid phase silicon carbide single crystal growth apparatus described in this embodiment, and includes the following steps:

[0071] ① Heating stage: The growth material is placed in the crucible body of the growth crucible, the furnace is evacuated, and then argon gas is introduced as a protective gas. Then the power is turned on to raise the temperature to 40°C above the melting point of the growth material, so that the growth material in the growth crucible melts into a liquid state. The growth material used in this embodiment is a mixture of Si, Cr and Al. In the growth material, the mass percentage of these three components is Si: 50%, Cr: 48%, and Al: 2%.

[0072] ② High-Temperature Adjustment Stage: The movable graphite block, filling the hole at the center of the bottom of the growth crucible, is pushed into the liquid growth material using a braking device. The distance the movable graphite block moves into the growth material solution (push-in distance) is 15mm. The distances between the growth material and the laser rangefinder before and after the movable graphite block is pushed in are recorded as h1 (523.67mm) and h2 (523.61mm), respectively. The distance difference Δh = h1 - h2 is obtained. After measuring this distance difference Δh, the movable graphite block is pulled back to its original position. Then, the movable graphite blocks in a row of holes filling the side wall of the growth crucible are pushed into the liquid growth material sequentially from top to bottom using the braking device. The distance between each movable graphite block and the growth material solution is 15mm. The distance difference between the growth material and the laser rangefinder is measured before and after each movable graphite block is pushed in. After measuring the distance difference for each movable graphite block, the corresponding movable graphite block is pulled back to its original position before the next movable graphite block is pushed in. The distance difference for each movable graphite block is compared with Δh. The minimum distance difference is generated when the second movable graphite block at the bottom of the liquid surface on the side wall of the growth crucible is pushed into the growth material solution, causing the high temperature line to shift (the set high temperature line is at the liquid surface of the growth material). Since the distance between the centers of the two movable graphite blocks is 12mm, the growth crucible is moved down by 12mm. At this time, the high temperature line of the growth crucible returns to the liquid surface, and the high temperature line adjustment is completed.

[0073] ③ Crystal growth stage: The seed crystal fixed on the seed crystal rod is lowered to contact the liquid growth material surface to grow silicon carbide single crystals. During the crystal growth stage, the rotation of the seed crystal and the growth crucible is controlled to ensure uniform composition of the growth material solution. At the same time, the rise or fall of the seed crystal and the growth crucible is controlled to ensure a stable liquid level height for the crystal and a suitable growth environment. In addition, during the crystal growth stage, the movable graphite blocks near the growth material liquid surface and near the bottom of the growth crucible are moved back and forth relative to the growth material by a braking device. The number of times the movable graphite blocks move back and forth is controlled to be 12 times / min, thereby reducing self-circulation convection and improving carbon utilization.

[0074] ④ Cooling and crystal removal stage: After growth is completed, the seed crystal is pulled out of the solution, and then the power is reduced to 0kW to stop the seed crystal and the growth crucible from rotating. The moving graphite block stops moving back and forth. After the growth material cools down with the furnace, the growth crucible is taken out from the single crystal growth furnace, and the obtained silicon carbide single crystal is taken out to obtain silicon carbide single crystal.

[0075] The liquid-phase silicon carbide single crystal growth apparatus described in this embodiment enables the confirmation and adjustment of high-temperature lines before crystal growth, significantly reducing experimental errors caused by high-temperature line misalignment. In multi-furnace silicon carbide single crystal growth, the product error rate caused by high-temperature line misalignment can be reduced to below 5%. Furthermore, the reduction of self-circulation convection during crystal growth improves carbon utilization, thereby enhancing crystal quality and resulting in an inclusion density of silicon carbide single crystals as low as 7 inclusions / cm³. 3 the following.

[0076] Example 3

[0077] This embodiment provides a liquid-phase silicon carbide single crystal growth apparatus, the structure of which is the same as that in Embodiment 1.

[0078] This embodiment also provides a method for growing silicon carbide single crystals using a liquid phase method, which is performed using the liquid phase silicon carbide single crystal growth apparatus described in this embodiment, and includes the following steps:

[0079] ① Heating stage: The growth material is placed in the crucible body of the growth crucible, the furnace is evacuated, and then argon gas is introduced as a protective gas. Then the power is turned on to raise the temperature to 40°C above the melting point of the growth material, so that the growth material in the growth crucible melts into a liquid state. The growth material used in this embodiment is a mixture of Si, Cr and Al. In the growth material, the mass percentage of these three components is Si: 50%, Cr: 48%, and Al: 2%.

[0080] ② High-Temperature Line Confirmation Stage: A movable graphite block, filling the hole at the center of the bottom of the growth crucible, is pushed into the liquid growth material using a braking device. The distance the movable graphite block moves into the growth material solution (push-in distance) is 15mm. The distances between the growth material and the laser rangefinder before and after the movable graphite block is pushed in are recorded using a laser rangefinder: h1 (523.67mm) and h2 (523.61mm), respectively. The distance difference Δh = h1 - h2 is obtained. After measuring this distance difference Δh, the movable graphite block is pulled back to its original position. Then, the movable graphite blocks filling a row of holes on the side wall of the growth crucible are... The movable graphite blocks are pushed into the liquid growth material solution sequentially from top to bottom via a braking device. The distance between each movable graphite block and the growth material solution is 15mm. The distance difference between the growth material and the laser rangefinder is measured before and after each movable graphite block is pushed in. After measuring the distance difference for each movable graphite block, the corresponding movable graphite block is pulled back to its original position before the next movable graphite block is pushed in. The distance difference for each movable graphite block is compared with Δh. The minimum distance difference is generated when the movable graphite block at the liquid surface on the side wall of the growth crucible is pushed into the growth material solution. The high temperature line is accurate (the set high temperature line is at the liquid surface of the growth material) and no adjustment is required.

[0081] ③ Crystal Growth Stage and Judgment of Growth Crucible Erosion Damage: The seed crystal fixed on the seed crystal rod is lowered to contact the liquid growth material surface for silicon carbide single crystal growth. During the crystal growth stage, the rotation of the seed crystal and the growth crucible is controlled to ensure uniform composition of the growth material solution. Simultaneously, the rise and fall of the seed crystal and the growth crucible are controlled to ensure a stable meniscus height and a suitable growth environment. Furthermore, during the crystal growth stage, movable graphite blocks near the growth material surface and near the bottom of the growth crucible are moved back and forth relative to the growth material using a braking device. The number of back-and-forth movements of the movable graphite blocks is controlled at 12 times / min to reduce self-circulation convection and improve carbon utilization. Additionally, after a period of crystal growth, during the crystal growth process, movable graphite blocks filled in a row of holes on the sidewall of the growth crucible are pushed sequentially from top to bottom into the liquid growth material using a braking device. The distance the movable graphite blocks are pushed into the growth material solution is 15mm, and this is measured using laser ranging. The instrument measures the distance differences between the growth material and the laser rangefinder before and after each movable graphite block is pushed in sequentially. If the distance difference measured by the laser rangefinder before and after a certain movable graphite block is pushed in is less than 0.01 mm, it indicates that the movable graphite block at that point has melted through or is about to melt through (in this embodiment, the liquid volume after a 10 mm diameter movable graphite block is pushed forward 15 mm can raise the height of the growth material liquid level by 0.06 mm. When the difference is less than 0.01 mm, it indicates that the thickness of the movable graphite block pushed into the growth material solution at a distance of 15 mm is less than 2.5 mm, which indicates that the movable graphite block has melted through or is about to melt through). If the high temperature line is maintained at that point, the growth solution will be in contact with the sealing graphite for a long time, and there is a possibility of leakage. At this time, it is necessary to adjust the high temperature line in time or pull out the crystal to enter the next stage of cooling and crystal removal. In this process, after measuring the distance difference corresponding to the movable graphite block, the corresponding movable graphite block is first pulled back to its original position before the next movable graphite block is pushed in.

[0082] ④ Cooling and crystal removal stage: After growth is completed, the seed crystal is pulled out of the solution, and then the power is reduced to 0kW to stop the seed crystal and the growth crucible from rotating. The moving graphite block stops moving back and forth. After the growth material cools down with the furnace, the growth crucible is taken out from the single crystal growth furnace, and the obtained silicon carbide single crystal is taken out to obtain silicon carbide single crystal.

[0083] The liquid-phase silicon carbide single crystal growth apparatus described in this embodiment enables the determination of whether the growth crucible has melted or been damaged during crystal growth, and allows for adjustments to the high-temperature line based on actual conditions. It also allows for quantitative assessment of melting at the high-temperature line, facilitating emergency handling of potential leaks. Furthermore, it reduces self-circulation convection during crystal growth, improving carbon utilization and thus enhancing crystal quality, resulting in an inclusion density of as low as 7 inclusions / cm³ in the silicon carbide single crystal. 3 the following.

[0084] Comparative Example 1

[0085] Liquid-phase silicon carbide single crystal growth is performed in a traditional liquid-phase silicon carbide single crystal growth apparatus. This apparatus includes a growth crucible for holding the growth material and a seed crystal rod with a seed crystal fixed to it. The growth crucible comprises a crucible body and a crucible lid, which are connected by a threaded connection. The growth material is contained within the crucible body. The crucible lid has an opening at its center. The lower end of the seed crystal rod, with the seed crystal fixed to it, extends into the interior of the crucible body through the opening. The lower end of the seed crystal rod is connected to a seed crystal holder for bonding the seed crystal. The seed crystal is located... At the bottom, the end of the seed crystal rod without the seed crystal fixed (the upper end) is connected to a transmission device, which is used to control the lifting and rotation of the seed crystal rod; the liquid phase silicon carbide single crystal growth apparatus also includes a heat insulation layer disposed on the outside of the growth crucible, and an induction heating device for heating is disposed on the outside of the heat insulation layer. The induction heating device includes an induction coil, which is coaxially disposed with the seed crystal rod, and the induction heating device heats the growth crucible through electromagnetic induction; the liquid phase silicon carbide growth apparatus also includes a crucible transmission device for rotating and lifting the growth crucible.

[0086] In this comparative example, the inner diameter of the growth crucible is 150 mm, and the thickness of the side wall and the bottom of the growth crucible are both 20 mm.

[0087] This comparative example uses a traditional liquid-phase silicon carbide single crystal growth apparatus to grow silicon carbide single crystals, including the following steps:

[0088] ① Heating stage: The growth material is placed in the crucible body of the growth crucible, the furnace is evacuated, and then argon gas is introduced as a protective gas. Then the power is turned on to raise the temperature to 40°C above the melting point of the growth material, so that the growth material in the growth crucible melts into a liquid state. The growth material used in this comparative example is a mixture of Si, Cr and Al. In the growth material, the mass percentage of these three components is Si: 50%, Cr: 48%, and Al: 2%.

[0089] ② Crystal growth stage: The seed crystal fixed on the seed crystal rod is lowered to contact the liquid growth material surface to grow silicon carbide single crystals; during the crystal growth stage, the rotation of the seed crystal and the growth crucible is controlled to make the composition of the growth material solution uniform, and the rise or fall of the seed crystal and the growth crucible is controlled to ensure a stable liquid bend height of the crystal and to ensure a suitable growth environment.

[0090] ③ Cooling and crystal removal stage: After growth is completed, the seed crystal is pulled out of the solution, and then the power is reduced to 0kW to stop the rotation of the seed crystal and the growth crucible. After the growth material is cooled with the furnace, the growth crucible is taken out from the single crystal growth furnace, and the obtained silicon carbide single crystal is taken out to obtain silicon carbide single crystal.

[0091] This comparative example uses a traditional liquid-phase silicon carbide growth apparatus. However, this apparatus results in a high experimental error rate due to high-temperature wire misalignment during silicon carbide single crystal growth. In multi-batch silicon carbide single crystal growth, the product error rate caused by high-temperature wire misalignment is 10–15%, and the inclusion density of the silicon carbide single crystal is 20–40 inclusions / cm³. 3 .

[0092] In the description of this invention, it should be noted that the terms "below", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in Figure 1, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0093] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a direct connection or an indirect connection through an intermediate medium, etc. Those skilled in the art can understand the specific meaning of this term in this invention depending on the specific circumstances.

[0094] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0095] 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. A liquid-phase silicon carbide single crystal growth apparatus, characterized in that: The growth apparatus includes a growth crucible for holding growth raw materials, a seed crystal rod with a seed crystal fixed thereon, a laser rangefinder for determining the position of the growth raw materials, a movable graphite block, a braking device, and a sealing graphite. The growth crucible includes a crucible body and a crucible lid. The crucible lid has a reserved hole located directly below the light output hole of the laser rangefinder. The growth crucible has multiple holes on its sidewall. The multiple holes are arranged in at least four rows at equal intervals on the sidewall of the growth crucible. The holes in each row are evenly distributed from top to bottom. A hole is opened at the center of the bottom of the growth crucible. The movable graphite block is filled in the hole. One end of the sealing graphite is embedded in the hole, and the other end is sleeved on the outer wall of the growth crucible. The sealing graphite has an opening in the center for the braking device to pass through. The braking device passes through the opening and is connected to the movable graphite block. The braking device is used to control the movable graphite block to move back and forth relative to the growth material.

2. The growth apparatus according to claim 1, characterized in that: The sidewall of the growth crucible has multiple holes extending from near the surface of the growth raw material liquid to near the bottom of the growth crucible. Each column contains at least two holes.

3. The growth apparatus according to claim 1, characterized in that: A recessed hole is provided at the position where the movable graphite block is connected to the braking device, and one end of the braking device is engaged in the recessed hole; The other end of the braking device is connected to a servo motor.

4. The growth apparatus according to claim 1, characterized in that: The crucible lid has an opening in the center, and the end of the seed crystal rod with the seed crystal fixed thereon extends into the interior of the crucible body through the opening. The end of the seed crystal rod without the seed crystal fixed is connected to a transmission device, which is used to control the lifting and rotation of the seed crystal rod.

5. The growth apparatus according to claim 1, characterized in that: The hole is cylindrical and has a diameter of 5–40 mm.

6. The growth apparatus according to claim 1, characterized in that: The hole is a fan-shaped annular hole, and the angle of the fan-shaped annulus is 30° to 90°.

7. The growth apparatus according to claim 1, characterized in that: The sidewall thickness and / or bottom thickness of the growth crucible is 10–40 mm; and / or The movable graphite block is connected to the hole in the growth crucible by a threaded connection or a slot connection.

8. The growth apparatus according to claim 1, characterized in that: The outer side of one end of the sealing graphite embedded in the hole is provided with a silicon carbide coating; and / or The growth raw material includes Si and a fluxing agent X, wherein the fluxing agent X is one or more of Al, B, Ti, Cr, Fe, Y, Yb, Pr, La, Cu, Ag, Nd, Ce, Sn, Ge, and Co.

9. A method for growing silicon carbide single crystals using a liquid-phase method, characterized in that, The growth method is performed using the liquid-phase silicon carbide single crystal growth apparatus as described in any one of claims 1 to 8, and the growth method includes the following steps: (1) The growth material is placed in the crucible body of the growth crucible and heated to melt the growth material into a liquid state; (2) The movable graphite block filled in the hole at the center of the bottom of the growth crucible is pushed into the liquid growth material by the braking device. The pushing distance is 3 / 4 of the bottom thickness of the growth crucible. The difference in distance between the growth material and the laser rangefinder before and after the movable graphite block is pushed in is measured by the laser rangefinder as Δh. After measuring the distance difference Δh, the movable graphite block is pulled back to its original position. (3) The movable graphite blocks filled in a row of holes on the side wall of the growth crucible are pushed into the liquid growth material from top to bottom through the braking device. The pushing distance is 3 / 4 of the thickness of the side wall of the growth crucible. The distance difference between the growth material and the laser rangefinder is measured before and after each movable graphite block is pushed in. After measuring the distance difference corresponding to each movable graphite block, the corresponding movable graphite block is pulled back to its original position before the next movable graphite block is pushed in. (4) Compare the distance difference corresponding to each active graphite block with Δh. The position of the active graphite block with the smallest distance difference is the position of the high temperature line. If the determined high temperature line position is inconsistent with the set high temperature line position, adjust the high temperature line position to be consistent with the set high temperature line position by moving the growth crucible. (5) After the operation in step (4) is completed, the seed crystal fixed on the seed crystal rod is lowered to contact the liquid growth material surface to grow silicon carbide single crystal and obtain silicon carbide single crystal; during the growth of silicon carbide single crystal, at least the movable graphite blocks on the side wall of the growth crucible near the liquid growth material surface and near the bottom of the growth crucible are moved back and forth relative to the growth material by the braking device.

10. The growth method according to claim 9, characterized in that: In step (5), the number of forward and backward movements is controlled to be 10 to 15 times / min.

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