Device for stably growing silicon carbide single crystal by liquid phase method and working method

Abstract

The invention belongs to the technical field of chemical metallurgy, and particularly relates to a device for stably growing silicon carbide single crystals by a liquid phase method and a working method.The device for stably growing the silicon carbide single crystals by the liquid phase method comprises an inner crucible, an outer crucible, a plurality of liquid discharging holes, a plurality of liquid discharging holes, a plurality of liquid discharging holes and a plurality of liquid discharging holes, the outer crucible is arranged on the periphery of the inner crucible in a sleeving mode, and an annular guide block used for stretching into the annular cavity and blocking the liquid drainage hole sets is arranged at the cavity bottom of the outer crucible; the driving shaft is connected with the outer crucible; the heater is positioned on the periphery of the outer crucible; the control module is electrically connected with the driving shaft; according to the device for stably growing the silicon carbide single crystals through the liquid phase method and the working method, the driving shaft rotates forwards to drive the outer crucible to descend, so that the annular guide block opens the liquid discharge hole group, and at the moment, the liquid level of a solution in the inner crucible is lowered to be away from a floating crystal.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of chemical metallurgy, and particularly relates to single crystal growth, and especially relates to a device for stably growing silicon carbide single crystals by a liquid phase method and a working method. BACKGROUND

[0002] Silicon carbide, as a representative of the third generation of semiconductor materials, has a wide range of applications in new energy vehicles, 5G communication, smart grids and other fields due to its excellent characteristics such as wide band gap, high breakdown field strength and high thermal conductivity.

[0003] In related technologies, in the process of crystal growth, the gradient in the solution is large, and the growth rate cannot be matched, which will crystallize at the edge of the crucible at the liquid surface, affecting the solution flow and crystal growth.

[0004] Therefore, how to solve the above problems is an urgent need for those skilled in the art.

[0005] It should be noted that the above information disclosed in the background section is only used to understand the background of the present application, and therefore, the above description is not considered to constitute prior art information. SUMMARY

[0006] The present application at least provides a device for stably growing silicon carbide single crystals by a liquid phase method and a working method.

[0007] In a first aspect, the present application provides a device for stably growing silicon carbide single crystals by a liquid phase method, comprising: an inner crucible, an annular chamber is opened in the side wall of the inner crucible, and the annular chamber is provided with a plurality of layer liquid outlet hole groups in communication with the inner crucible; an outer crucible, which is sleeved on the periphery of the inner crucible, and the cavity bottom is provided with an annular guide block for extending into the annular chamber and plugging each liquid outlet hole group; a drive shaft connected with the outer crucible; a heater located outside the outer crucible; a control module electrically connected with the drive shaft; wherein when floating crystals appear on the inner wall of the inner crucible, the control module is configured to control the drive shaft to drive the outer crucible to descend to open the liquid outlet hole group, so that the solution in the inner crucible is guided into the annular chamber through the liquid outlet hole group, and the liquid level of the solution in the inner crucible is lowered to move away from the floating crystal, and is also configured to control the drive shaft to drive the outer crucible to rise after the outer crucible is lowered, that is, part of the high-temperature solution in the annular chamber is injected back into the inner crucible to increase the temperature of the solution liquid surface in the inner crucible.

[0008] In an alternative embodiment, the device for stable growth of silicon carbide single crystal by liquid phase method further comprises a seed rod for extending into the inner graphite crucible to contact the solution surface; wherein the seed rod is connected with a driver; the control module is electrically connected with the driver and is configured to control the driver to rotate and pull the seed rod to grow silicon carbide single crystal thereon; when the floating crystal appears on the inner wall of the inner crucible, the control module is further configured to control the driver to stop rotating and pulling the seed rod and control the driver to lift the seed rod to follow the outer crucible so that the silicon carbide single crystal on the seed rod is always in contact with the solution surface.

[0009] In an alternative embodiment, the driving shaft passes through the outer crucible from bottom to top and extends into the inner crucible; wherein the driving shaft is threadedly connected with the outer crucible; the inner wall of the outer crucible is provided with an anti-rotation block; the driving shaft is adapted to lift the outer crucible by rotating.

[0010] In an alternative embodiment, the periphery of the heater is provided with a graphite shielding cylinder; wherein the inner crucible is connected with the graphite shielding cylinder through a graphite fixing piece.

[0011] In an alternative embodiment, the driving shaft is rotationally connected with the inner crucible; the extending end of the driving shaft is provided with a "T" type stirring head; when the floating crystal appears on the inner wall of the inner crucible, the control module is configured to control the driving shaft to rotate, i.e. the "T" type stirring head generates convection of the solution in the inner crucible by rotating.

[0012] In an alternative embodiment, the periphery of the graphite shielding cylinder is provided with graphite insulation felt.

[0013] In a second aspect, the embodiments of the present disclosure further provide a working method of a device for stable growth of silicon carbide single crystal by liquid phase method, comprising: extending a seed rod into a graphite inner crucible to contact the solution surface; controlling a heater to heat the solution in the inner crucible; controlling the seed rod to rotate and pull to grow silicon carbide single crystal thereon; when the floating crystal appears on the inner wall of the inner crucible, controlling the driving shaft to rotate to lift the outer crucible to separate the solution surface from the floating crystal.

[0014] In an alternative embodiment, the method of controlling the driving shaft to rotate to lift the outer crucible to separate the solution surface from the floating crystal when the floating crystal appears on the inner wall of the inner crucible comprises: when the floating crystal appears on the inner wall of the inner crucible, controlling the driving shaft to rotate forward to lower the outer crucible, and opening the group of liquid discharge holes through the annular guide block to separate the solution surface from the floating crystal; controlling the driving shaft to rotate reversely to lift the outer crucible to inject part of the high-temperature solution in the annular chamber back into the inner crucible through the annular guide block.

[0015] In an optional embodiment, when floating crystals appear on the inner wall of the inner crucible, the method of controlling the drive shaft to rotate and drive the outer crucible to rise and fall so that the solution surface is separated from the floating crystals further includes: during the raising and lowering of the outer crucible, controlling the seed crystal rod to stop rotating and pulling, and controlling the seed crystal rod to follow the raising and lowering of the outer crucible so that the silicon carbide single crystal on the seed crystal rod comes into contact with the solution surface.

[0016] In an optional embodiment, the method of controlling the rotation of the drive shaft to drive the outer crucible to rise and fall when floating crystals appear on the inner wall of the inner crucible so that the solution surface is separated from the floating crystals further includes: during the rotation of the drive shaft, the solution in the inner crucible is convected by a "T"-shaped stirring head on the extension end of the drive shaft.

[0017] In one alternative embodiment, in the method of controlling the drive shaft to reverse and drive the outer crucible to rise so that the annular guide block injects part of the high-temperature solution in the annular cavity back into the inner crucible, the amount of solution injected back into the inner crucible is less than the amount of solution discharged into the annular cavity through the drain hole group.

[0018] The beneficial effects of this invention are as follows: When floating crystals appear on the inner wall of the inner crucible, the control module controls the drive shaft to lower the outer crucible, causing the annular guide block to open the drain hole group. At this time, the solution enters the annular chamber through the drain hole group, lowering the liquid level of the solution in the inner crucible away from the floating crystals, thereby avoiding the presence of crystals affecting solution flow and crystal growth. Furthermore, after the solution enters the annular chamber, the solution inside the annular chamber heats up rapidly due to its proximity to the heater. At this time, the drive shaft raises the outer crucible to inject some of the high-temperature solution from the annular chamber back into the inner crucible (after injection, the liquid level of the solution in the inner crucible remains away from the floating crystals), thereby increasing the temperature at the solution surface and reducing the probability of recrystallization. Also, during the raising and lowering of the outer crucible, the seed crystal rod stops rotating and instead follows the raising and lowering of the outer crucible to ensure that the silicon carbide single crystal is always in contact with the solution, preventing loss of contact and thus affecting the growth of the silicon carbide single crystal.

[0019] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0021] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings also belong to the protection scope of the present application.

[0022] Figure 1 A structure schematic diagram of an inner and outer crucible provided by the embodiment of the present application is provided. Figure 2 A structure schematic diagram of an inner and outer crucible provided by the embodiment of the present application is provided. Figure 3 A structure schematic diagram after liquid surface falling provided by the embodiment of the present application is provided. Figure 4 A structure schematic diagram of a device for growing silicon carbide single crystal provided by the embodiment of the present application is provided.

[0023] In the drawings: 1, inner crucible; 11, annular chamber; 12, liquid discharge hole group; 13, graphite fixing piece; 14, anti-rotation notch; 2, outer crucible; 21, annular guide block; 22, anti-rotation block; 3, driving shaft; 31, "T" type stirring head; 4, seed rod; 5, heater; 6, graphite shielding cylinder; 7, graphite insulation felt; 8, floating crystal. Specific embodiments

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the present application will be described clearly and completely below by combining with the drawings. Obviously, the described embodiments are some embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0025] In the process of crystal growth, the gradient in the solution is large, and the growth speed cannot be matched, which will crystallize at the edge of the crucible of the liquid surface, affecting the solution flow and crystal growth.

[0026] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, in the drawings, in order to effectively describe the technical content, the thickness of the components can be exaggerated or reduced.

[0027] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0028] like Figures 1 to 3 As shown, at least one embodiment provides an apparatus for the stable growth of silicon carbide single crystals by liquid phase method, including: an inner crucible 1, an outer crucible 2, a drive shaft 3, a seed crystal rod 4, a heater 5, and a control module.

[0029] Specifically, an annular chamber 11 is provided in the side wall of the inner crucible 1, and the bottom of the annular chamber 11 is open. Several layers of drainage hole groups 12 are provided in the inner wall of the annular chamber 11, and the drainage hole groups 12 are connected to the chamber of the inner crucible 1 used to hold the solution.

[0030] Specifically, the outer crucible 2 is fitted around the inner crucible 1, and an annular guide block 21 is provided at the bottom of the outer crucible 2. The annular guide block 21 extends into the annular chamber 11 to block each drain hole group 12.

[0031] Specifically, the drive shaft 3 is connected to the outer crucible 2 and is used to drive the outer crucible 2 to rise and fall.

[0032] Specifically, the seed crystal rod 4 is used to extend into the inner crucible 1 and contact the liquid surface of the solution. The seed crystal rod 4 is connected to a driver, which drives the seed crystal rod 4 to rotate and pull so that silicon carbide single crystals are grown on the seed crystal rod 4. Optionally, the driver consists of a turntable and a lifting shaft. The turntable is set on the lifting shaft, and the seed crystal rod 4 is connected to the turntable.

[0033] Specifically, the heater 5 is located around the outer crucible 2 and is used to heat the solution; wherein, the annular chamber 11 is closer to the heater 5 than the accommodating cavity at the axis of the inner crucible 1.

[0034] Specifically, the control module may be, but is not limited to, using a PLC; the control module is electrically connected to drive shaft 3 and the driver.

[0035] In the embodiment, when the operator observes the float crystal on the inner wall of the inner crucible 1, the operator performs corresponding operation through the touch panel, that is, the control module controls the driving shaft 3 to drive the outer crucible 2 to descend to a height so that the annular guide block 21 opens the drainage hole group 12, at this time, the solution enters the annular chamber 11 through the drainage hole group 12, so that the liquid level of the solution in the inner crucible 1 is lowered to be far away from the float crystal 8, thereby avoiding the influence of the crystal on the solution flow and the crystal growth; and after the solution enters the annular chamber 11, the solution in the annular chamber 11 is rapidly heated because it is closer to the heater 5, at this time, the driving shaft 3 drives the outer crucible 2 to ascend to a part of the height to inject part of the high-temperature solution in the annular chamber 11 back to the inner crucible 1 (after the injection, the solution in the inner crucible 1 is still far away from the float crystal 8), thereby increasing the temperature at the solution liquid level and reducing the probability of the solution re-crystallization; and in the process of the outer crucible 2 ascending and descending, the seed rod 4 stops rotating and pulling and instead follows the outer crucible 2 to ascend and descend, so that the silicon carbide single crystal is always in contact with the solution, thereby avoiding the influence on the growth of the silicon carbide single crystal caused by the disconnection.

[0036] In some embodiments, the inner crucible 1, the outer crucible 2 and the seed rod 4 are all made of graphite.

[0037] In some embodiments, the drainage hole group 12 has multiple layers, and the spacing between adjacent layers is the same.

[0038] As shown in FIG. 1, Figure 4 In some embodiments, the driving shaft 3 penetrates the outer crucible 2 from bottom to top and extends into the inner crucible 1; the driving shaft 3 is threadedly connected with the outer crucible 2; the inner wall of the outer crucible 2 is provided with an anti-rotation block 22; and the driving shaft 3 is adapted to drive the outer crucible 2 to ascend and descend by rotating.

[0039] Specifically, the driving shaft 3 rotates forward to drive the outer crucible 2 to descend, and the driving shaft 3 rotates reversely to drive the outer crucible 2 to ascend.

[0040] In the embodiment, the sidewall of the inner crucible 1 is provided with an anti-rotation notch 14, and the anti-rotation block 22 is located in the anti-rotation notch 14, so that the driving shaft 3 rotates to drive the outer crucible 2 to ascend and descend along the axial direction.

[0041] As shown in FIG. 1, Figure 4 In some embodiments, the periphery of the heater 5 is provided with a graphite shielding cylinder 6, and the periphery of the graphite shielding cylinder 6 is provided with a graphite heat insulation felt 7; and the inner crucible 1 is connected with the graphite shielding cylinder 6 through a graphite fixing piece 13.

[0042] In the embodiment, the inner crucible 1 is connected with the graphite shielding cylinder 6 through the graphite fixing piece 13, that is, the position of the inner crucible 1 is fixed, and in the working process, the outer crucible 2 ascends and descends relative to the inner crucible 1.

[0043] As shown in FIG. 1, Figure 4As shown, in some embodiments, the driving shaft 3 is rotationally connected with the inner crucible 1; the extending end of the driving shaft 3 is provided with a "T" type stirring head 31; the "T" type stirring head 31 is located in the inner crucible 1; when the float crystal appears on the inner wall of the inner crucible 1, the control module is configured to control the rotation of the driving shaft 3, that is, the "T" type stirring head 31 causes the convection of the solution in the inner crucible 1 by rotation.

[0044] In the present embodiment, the driving shaft 3 drives the "T" type stirring head 31 to rotate synchronously during rotation, and the rotation of the "T" type stirring head 31 causes the convection of the solution in the inner crucible 1, thereby ensuring the uniformity of the carbon concentration in the solution.

[0045] At least one embodiment also provides a method for the operation of the device for the stable growth of silicon carbide single crystals by the liquid phase method, comprising: extending the seed rod 4 into the graphite inner crucible 1 to contact the solution surface; controlling the heater 5 to heat the solution in the inner crucible 1; controlling the rotation and pulling of the seed rod 4 to grow silicon carbide single crystals thereon; when the float crystal appears on the inner wall of the inner crucible 1, controlling the rotation of the driving shaft 3 to drive the outer crucible 2 to ascend and descend to separate the solution surface from the float crystal.

[0046] For the specific structure and implementation process of the device for the stable growth of silicon carbide single crystals by the liquid phase method, see the relevant discussion in the above embodiments, which will not be repeated here.

[0047] In the present embodiment, when the float crystal appears on the inner wall of the inner crucible 1, the driving shaft 3 drives the outer crucible 2 to descend by forward rotation to open the drainage hole group 12 through the annular guide block 21, and at this time the solution enters the annular chamber 11 to lower the solution surface height in the inner crucible 1 to be far away from the float crystal, thereby avoiding the influence of the existence of the crystal on the solution flow and the crystal growth.

[0048] In some embodiments, when the float crystal appears on the inner wall of the inner crucible 1, the method for controlling the rotation of the driving shaft 3 to drive the outer crucible 2 to ascend and descend to separate the solution surface from the float crystal comprises: when the float crystal appears on the inner wall of the inner crucible 1, controlling the forward rotation of the driving shaft 3 to drive the outer crucible 2 to descend, and opening the drainage hole group 12 through the annular guide block 21 to separate the solution surface from the float crystal; controlling the reverse rotation of the driving shaft 3 to drive the outer crucible 2 to ascend, so that the annular guide block 21 injects part of the high-temperature solution in the annular chamber 11 back into the inner crucible 1.

[0049] In the present embodiment, after the solution enters the annular chamber 11, the solution in the annular chamber 11 is rapidly heated due to being closer to the heater 5, and at this time the driving shaft 3 drives part of the high-temperature solution in the annular chamber 11 back into the inner crucible 1 by reverse rotation (after back injection, the solution surface in the inner crucible 1 is still far away from the float crystal), thereby increasing the temperature at the solution surface and reducing the probability of re-crystallization of the solution.

[0050] In some embodiments, when floating crystals appear on the inner wall of the inner crucible 1, the method of controlling the drive shaft 3 to rotate and drive the outer crucible 2 to rise and fall so that the solution surface is separated from the floating crystals further includes: during the rising and falling of the outer crucible 2, controlling the seed crystal rod 4 to stop rotating and pulling, and controlling the seed crystal rod 4 to follow the rising and falling of the outer crucible 2 so that the silicon carbide single crystal on the seed crystal rod 4 comes into contact with the solution surface.

[0051] In this embodiment, during the forward and reverse rotation of the drive shaft 3, the seed crystal rod 4 stops rotating and is pulled up and down with the outer crucible 2 to ensure that the silicon carbide single crystal is always in contact with the solution, thus avoiding the loss of contact and affecting the growth of the silicon carbide single crystal.

[0052] In some embodiments, when floating crystals appear on the inner wall of the inner crucible 1, the method of controlling the rotation of the drive shaft 3 to drive the outer crucible 2 to rise and fall so that the solution surface is separated from the floating crystals further includes: during the rotation of the drive shaft 3, the solution in the inner crucible 1 is made to convect by the "T"-shaped stirring head 31 on the extension end of the drive shaft 3.

[0053] In this embodiment, during the rotation of the drive shaft 3, the "T"-shaped stirring head 31 will rotate accordingly. At this time, the rotation of the "T"-shaped stirring head 31 will cause convection in the solution in the inner crucible 1, thereby ensuring the uniformity of carbon concentration in the solution.

[0054] In some embodiments, in the method of controlling the drive shaft 3 to reverse and drive the outer crucible 2 to rise so that the annular guide block 21 injects part of the high-temperature solution in the annular chamber 11 back into the inner crucible 1, the amount of solution injected back into the inner crucible 1 is less than the amount of solution discharged into the annular chamber 11 through the drain hole group 12.

[0055] In this embodiment, the amount of solution refilled into the inner crucible 1 is less than the amount of solution discharged into the annular chamber 11 through the drainage hole group 12, ensuring that the solution level in the inner crucible 1 remains far away from the floating crystal after refilling.

[0056] In summary, the device and working method for stably growing silicon carbide single crystal by liquid phase method can achieve the following effects: when the floating crystal appears on the inner wall of the inner crucible 1, the driving shaft 3 drives the outer crucible 2 to descend by positive rotation, so that the annular guide block 21 opens the liquid discharge hole group 12, at this time, the solution enters the annular chamber 11, so that the solution liquid level in the inner crucible 1 is lowered to be far away from the floating crystal, thereby avoiding the existence of the crystal to affect the solution flow and the crystal growth; and after the solution enters the annular chamber 11, the solution in the annular chamber 11 is rapidly heated because it is closer to the heater 5, at this time, the driving shaft 3 reverses to inject part of the high-temperature solution in the annular chamber 11 back to the inner crucible 1 (after the injection, the solution liquid level in the inner crucible 1 is still far away from the floating crystal), thereby increasing the temperature at the solution liquid level and reducing the probability of re-crystallization of the solution; and during the positive and reverse rotation of the driving shaft 3, the seed rod 4 stops rotating and pulling up, and instead follows the outer crucible 2 to ascend and descend, so that the silicon carbide single crystal is always in contact with the solution, thereby avoiding the separation of the silicon carbide single crystal from the solution to affect the growth of the silicon carbide single crystal.

[0057] In this document, when a first component is referred to as being on a second component, this can mean that the first component can be directly formed on the second component, or a third component can be interposed between the first component and the second component.

[0058] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the terms “mount”, “connect”, “connection” should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be direct connection, can also be indirect connection through intervening medium, can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0059] In addition, terms such as “first”, “second” and other numerical terms are used herein without implying a sequential or chronological order, unless explicitly indicated above. Therefore, the first element, component, region, layer or section discussed above can be referred to as the second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0060] Spatially relative terms, such as “inner”, “outer”, “below”, “below”, “lower”, “upper”, “above”, and the like, can be used herein to facilitate description of the relationship of one element or feature to another element or feature as illustrated in the drawings.

[0061] In the above discussion, unless otherwise stated, the terms “about”, “approximately”, “substantially” and the like mean a + / - 10% variation of the value when used to describe a numerical value.

[0062] With the above ideal embodiments according to the present application as the inspiration, through the above description, relevant staff can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. An apparatus for stable growth of a silicon carbide single crystal by a liquid phase method, characterized by comprising: The device comprises: an inner crucible (1) with a side wall in which an annular chamber (11) is formed, the annular chamber (11) being provided with a plurality of groups (12) of liquid discharge holes in communication with the inner crucible (1); an outer crucible (2) sleeved on the periphery of the inner crucible (1), the cavity bottom of the outer crucible (2) being provided with an annular guide block (21) for extending into the annular chamber (11) and plugging the groups (12) of liquid discharge holes; a drive shaft (3) connected with the outer crucible (2); a heater (5) located on the periphery of the outer crucible (2); a control module electrically connected with the drive shaft (3); wherein when floating crystals appear on the inner wall of the inner crucible (1), the control module is configured to control the drive shaft (3) to drive the outer crucible (2) to descend so as to open the groups (12) of liquid discharge holes by the annular guide block (21), so as to guide the solution in the inner crucible (1) into the annular chamber (11) through the groups (12) of liquid discharge holes, and to lower the liquid level of the solution in the inner crucible (1) to move away from the floating crystals, and is further configured to control the drive shaft (3) to drive the outer crucible (2) to ascend after the outer crucible (2) stops descending, so as to inject part of the high-temperature solution in the annular chamber (11) back into the inner crucible (1) to increase the temperature of the solution in the inner crucible (1).

2. The apparatus for stable growth of a silicon carbide single crystal by a liquid phase method according to claim 1, wherein Further comprising: a seed rod (4) for extending into the inner crucible (1) to contact the liquid surface of the solution; wherein the seed rod (4) is connected with a driver; the control module is electrically connected with the driver and is configured to control the driver to drive the seed rod (4) to rotate and pull up, so as to grow silicon carbide single crystals on the seed rod (4); when floating crystals appear on the inner wall of the inner crucible (1), the control module is further configured to control the driver to stop the rotation and pulling up of the seed rod (4), and to control the driver to drive the seed rod (4) to ascend and descend along with the outer crucible (2), so as to keep the silicon carbide single crystals on the seed rod (4) in contact with the liquid surface of the solution.

3. The device for stable growth of silicon carbide single crystals by liquid phase method according to claim 2, wherein the drive shaft (3) extends into the inner crucible (1) from bottom to top through the outer crucible (2); wherein the drive shaft (3) is threadedly connected with the outer crucible (2); the inner wall of the outer crucible (2) is provided with an anti-rotation block (22); the drive shaft (3) is adapted to drive the outer crucible (2) to ascend and descend by rotating.

4. The device for stable growth of silicon carbide single crystals by liquid phase method according to claim 3, wherein the periphery of the heater (5) is provided with a graphite shielding cylinder (6); wherein the inner crucible (1) is connected with the graphite shielding cylinder (6) through a graphite fixing member (13).

5. The device for stable growth of silicon carbide single crystals by liquid phase method according to claim 4, wherein the drive shaft (3) is rotationally connected with the inner crucible (1); the extending end of the drive shaft (3) is provided with a "T"-shaped stirring head (31); when floating crystals appear on the inner wall of the inner crucible (1), the control module is configured to control the drive shaft (3) to rotate, i.e. the "T"-shaped stirring head (31) generates convection of the solution in the inner crucible (1) by rotating.

6. The device for stable growth of silicon carbide single crystals by liquid phase method according to claim 5, wherein The graphite shielding cylinder (6) is provided with a graphite heat insulation felt (7) on the periphery.

7. A method of operating an apparatus for stable growth of a silicon carbide single crystal by the liquid phase method according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: The seed rod (4) is inserted into the graphite inner crucible (1) to contact the solution surface; The heater (5) is controlled to heat the solution in the inner crucible (1); The seed rod (4) is controlled to rotate and pull to grow silicon carbide single crystal thereon; When the floating crystal appears on the inner wall of the inner crucible (1), the driving shaft (3) is controlled to rotate to drive the outer crucible (2) to ascend and descend to separate the solution surface from the floating crystal.

8. The working method of the device for stably growing silicon carbide single crystal by liquid phase method according to claim 7, wherein The method of controlling the driving shaft (3) to rotate to drive the outer crucible (2) to ascend and descend to separate the solution surface from the floating crystal when the floating crystal appears on the inner wall of the inner crucible (1) comprises: When the floating crystal appears on the inner wall of the inner crucible (1), the driving shaft (3) is controlled to rotate forward to drive the outer crucible (2) to descend, and the ring-shaped guide block (21) is controlled to open the liquid discharge hole group (12) to separate the solution surface from the floating crystal; The driving shaft (3) is controlled to rotate reversely to drive the outer crucible (2) to ascend, so that the ring-shaped guide block (21) injects part of the high-temperature solution in the ring-shaped chamber (11) back into the inner crucible (1).

9. The working method of the device for stably growing silicon carbide single crystal by liquid phase method according to claim 8, wherein During the ascending and descending of the outer crucible (2), the rotation and pulling of the seed rod (4) are stopped, and the seed rod (4) is controlled to ascend and descend with the outer crucible (2) to make the silicon carbide single crystal on the seed rod (4) contact the solution surface; During the rotation of the driving shaft (3), the "T"-shaped stirring head (31) on the extending end of the driving shaft (3) is controlled to make the solution in the inner crucible (1) produce convection.

10. The working method of the device for stably growing silicon carbide single crystal by liquid phase method according to claim 8, wherein The amount of the solution injected back into the inner crucible (1) is less than the amount of the solution discharged into the ring-shaped chamber (11) through the liquid discharge hole group (12).

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