Growth device and growth method for silicon carbide single crystal

Abstract

The invention provides a growth device and method for silicon carbide single crystals, and belongs to the technical field of silicon carbide crystal growth. The growth device for the silicon carbide single crystals comprises a crucible, a seed crystal fixing assembly, a raw material area, a graphite cylinder and a heat preservation structure; the crucible is provided with a first cavity located in the center and a second cavity located on the periphery of the first cavity, and the top and the bottom of the crucible are sunken to form temperature measuring grooves; the seed crystal fixing assembly comprises an upper fixing piece arranged at the top in the first cavity and a lower fixing piece arranged at the bottom in the first cavity, and the upper fixing piece and the lower fixing piece are located in the space of the periphery of the seed crystal to define a growth cavity; the raw material area is arranged in the second cavity and deviates from a circle of the growth cavity; the graphite cylinder is arranged on the inner circumference of the raw material area, and an opening is formed in the graphite cylinder; the heat preservation structure is arranged on the periphery of the crucible and provided with a through hole corresponding to the temperature measuring groove.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicon carbide crystal growth, and in particular relates to a growth device and a growth method for a silicon carbide single crystal. Background Art

[0002] Silicon carbide has excellent material properties such as large bandgap, high thermal conductivity, and high carrier mobility. It is considered to be an ideal material for making high-temperature, high-frequency, high-power and high-voltage devices. Silicon carbide single crystal is the basic material for making silicon carbide-based devices. The methods for preparing silicon carbide single crystal ingots mainly include high-temperature vapor deposition, liquid phase method and physical vapor transport method (PVT method for short). The vast majority of single crystal substrates on the market are made by the PVT method. The PVT method grows high-quality crystals by sublimating the material at high temperature and then crystallizing it in a low-temperature area. During the growth of single crystals using this method, the dislocation lines of the threading dislocations (including screw dislocations and edge dislocations) in the seed crystal are basically parallel to the growth direction, causing the threading dislocations in the seed crystal to extend to the epitaxial layer, thereby increasing the threading dislocation defect density in the formed single crystal ingot and reducing the performance and reliability of power devices made using the ingot. Summary of the invention

[0003] The embodiments of the present invention provide a growth device and a growth method for a silicon carbide single crystal, aiming to solve the technical problem that the density of threading dislocation defects is high during the growth of existing silicon carbide single crystals using the PVT method, which reduces the performance and reliability of power devices made using the crystal ingot.

[0004] In a first aspect, an embodiment of the present invention provides a silicon carbide single crystal growth device, comprising: A crucible, comprising a first cavity located in the center and a second cavity located outside the first cavity, the first cavity and the second cavity are connected, the top surface of the second cavity is higher than the top surface of the first cavity, and the bottom surface is lower than the bottom surface of the first cavity, the top and bottom of the crucible are both recessed to form temperature measuring grooves, and the two temperature measuring grooves are located at the top and bottom of the first cavity; A seed crystal fixing assembly, comprising an upper fixing member disposed at the top of the first cavity and a lower fixing member disposed at the bottom of the first cavity, wherein the space around the seed crystal formed by the upper fixing member and the lower fixing member encloses a growth cavity, and the width of the growth cavity gradually increases in a direction approaching the second cavity; A raw material area, arranged in a circle in the second cavity away from the growth cavity; A graphite cylinder is arranged on the inner periphery of the raw material area, and the graphite cylinder is provided with an opening; The heat-insulating structure is arranged on the outer periphery of the crucible, and the heat-insulating structure has a through hole corresponding to the temperature measuring tank.

[0005] In combination with the first aspect, in a possible implementation manner, the upper fixing member and the lower fixing member both include: A graphite sheet is fixedly connected to the top wall or the bottom wall in the first cavity, the middle of the graphite sheet has a mounting hole, the top surface of the graphite sheet is recessed to form a cylindrical cavity coaxial with the mounting hole, and the diameter of the cavity is larger than the diameter of the mounting hole; An insertion rod, matched with the mounting hole; A fixed plate, fixedly connected to one end of the insertion rod facing the seed crystal; The diameters of the fixing plate and the cavity are both smaller than the diameter of the seed crystal, and the bottom surface of the graphite sheet in the upper fixing member and the top surface of the graphite sheet in the lower fixing member enclose the growth cavity.

[0006] In combination with the first aspect, in a possible implementation manner, both the top wall and the bottom of the first cavity are provided with limiting rings, and the graphite sheet is snap-fitted to the inner ring of the limiting ring.

[0007] In combination with the first aspect, in a possible implementation manner, a diameter of the fixing plate is smaller than a diameter of the cavity.

[0008] In combination with the first aspect, in a possible implementation manner, the heat preservation structure includes: An outer insulation layer is wrapped around the outer circumference of the crucible, the outer insulation layer corresponds to the second cavity of the crucible, and the top and bottom of the outer insulation layer are respectively provided with temperature measuring holes corresponding to the temperature measuring tank; The inner thermal insulation layer is respectively arranged on the side walls of the two temperature measuring grooves, and the inner diameter of the inner thermal insulation layer is smaller than the diameter of the temperature measuring hole.

[0009] In combination with the first aspect, in a possible implementation, the thickness of the inner insulation layer is greater than 10 mm.

[0010] In combination with the first aspect, in a possible implementation, the wall thickness of the outer insulation layer at the top and bottom of the crucible is equal, and the ratio of the wall thickness of the insulation layer at the top of the crucible to the wall thickness of the outer periphery of the crucible is greater than 3:1.

[0011] In combination with the first aspect, in a possible implementation manner, a height ratio of the second cavity to the first cavity is 3:2-4:1.

[0012] The scheme shown in the embodiment of the present application is compared with the prior art. The cross-section of the first cavity and the second cavity of the crucible in the growth device for silicon carbide single crystal of the present invention is H-shaped. The heating area of ​​the entire growth device or the area directly receiving the heat radiation of the heater is the outer peripheral side wall of the crucible. The second cavity corresponding to the outer peripheral side wall has a larger electromagnetic induction or heat radiation receiving area, which is convenient for efficient heating to meet the sublimation of silicon carbide powder (raw material); and the second cavity can ensure a larger loading space, avoid the temperature increase of the cost of insulation materials caused by the expansion of the outer diameter of the crucible, and also avoid the problem of crystallization of the material surface caused by the larger radial thickness of the raw material; the top and bottom of the crucible are set The temperature measuring groove can ensure that the temperature measurement position is closer to the first cavity, so that the temperature measurement value can accurately reflect the axial temperature gradient of the growth cavity, which is convenient for controlling the axial temperature gradient of the growth cavity and reducing the risk of polycrystalline deposition in the growth cavity; the width of the growth cavity in the direction close to the second cavity gradually increases, and the isotherm of the growth cavity can be modulated to present a convex shape in the middle, thereby reducing the risk of adhesion between the seed crystal and the upper fixing member or the lower fixing member during the growth process; the traditional growth mainly relies on the axial temperature gradient. The seed crystal in the growth device of the present invention grows sideways, and the growth direction is perpendicular to the dislocation line of the threading dislocation in the seed crystal, which can effectively prevent the threading dislocation from extending into the growing single crystal.

[0013] In a second aspect, an embodiment of the present invention further provides a method for growing a silicon carbide single crystal, using the above-mentioned silicon carbide single crystal growth device, comprising the following steps: S10: taking an initial seed crystal, wherein the initial seed crystal is a columnar structure, and fixing the initial seed crystal between the upper fixing member and the lower fixing member; S20: Waiting for the initial seed crystal to grow for a preset time, and forming an annular growth zone on the periphery of the initial seed crystal; S30: removing the initial seed crystal with the growth zone, and digging out the columnar growth seed crystal in the growth zone; S40: Fixing the growth seed crystal between the upper fixture and the lower fixture until a whole ingot of silicon carbide single crystal is grown.

[0014] Compared with the prior art, the solution shown in the embodiment of the present application is to form a growth zone on the periphery of the initial seed crystal through growth, and then dig out a columnar growth seed crystal in the growth zone, and then use the growth seed crystal to grow in the same way to form a whole ingot of silicon carbide single crystal. The whole ingot of silicon carbide single crystal can be used as a production material for power devices, which can improve the performance and reliability of the power devices.

[0015] In conjunction with the second aspect, in a possible implementation manner, before step S10, the step further includes: A corrosion-resistant coating is applied to the upper and lower end surfaces of the initial seed crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic cross-sectional structure diagram of a silicon carbide single crystal growth device provided in an embodiment of the present invention; Figure 2 For along Figure 1 Schematic diagram of the cross-sectional structure of the CC line; Figure 3 A schematic diagram of the regional distribution of a silicon carbide single crystal growth device provided in an embodiment of the present invention; Figure 4 This is a relationship diagram between the initial seed crystal and the growth seed crystal used in the embodiment of the present invention.

[0017] Description of reference numerals: 10-crucible; 11-first cavity; 12-second cavity; 13-temperature measuring tank; 14-limiting ring; 20-upper fixing member; 21-lower fixing member; 22-graphite sheet; 23-insertion rod; 24-fixing plate; 25-growth chamber; 30-Raw material area; 40-graphite cylinder; 50-insulation structure; 51-through hole; 52-outer insulation layer; 53-inner insulation layer; 60-initial seed crystal; 70-Growing seed crystal. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] In the claims, description and the above-mentioned drawings of the present invention, unless otherwise clearly defined, the use of terms such as "first", "second" or "third" etc. are for distinguishing different objects rather than for describing a specific order.

[0020] Unless otherwise expressly defined, the directional words in the claims, specification and the above-mentioned drawings of the present invention, such as the use of terms such as "upper", "lower", "top", "bottom", "front", "back", "inside", "outside", "center", "lateral", "longitudinal", "horizontal", "vertical", "left", "right", "clockwise", "counterclockwise", "high", "low", etc., indicating directions or positional relationships are based on the directions and positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the specific protection scope of the present invention.

[0021] In the claims, specification and the above drawings of the present invention, unless otherwise clearly defined, if the term "fixed connection" or "fixed connection" is used, it should be understood in a broad sense, that is, any connection method without a displacement relationship and relative rotation relationship between the two, that is to say, including non-detachable fixed connection, detachable fixed connection, integrated connection and fixed connection through other devices or elements.

[0022] In the claims, description and drawings of the present invention, if the terms "include", "have" and their variations are used, they are intended to mean "including but not limited to".

[0023] Please also read Figures 1 to 3 , the silicon carbide single crystal growth device provided by the present invention is now described. The silicon carbide single crystal growth device includes a crucible 10, a seed crystal fixing assembly, a raw material area 30, a graphite cylinder 40 and a heat preservation structure 50. The crucible 10 has a first cavity 11 located in the center and a second cavity 12 located on the periphery of the first cavity 11. The first cavity 11 and the second cavity 12 are connected. The top surface of the second cavity 12 is higher than the top surface of the first cavity 11, and the bottom surface is lower than the bottom surface of the first cavity 11. The top and bottom of the crucible 10 are both recessed to form temperature measuring grooves 13. The two temperature measuring grooves 13 are located at the top and bottom of the first cavity 11; the seed crystal fixing assembly It includes an upper fixing member 20 arranged at the top of the first cavity 11 and a lower fixing member 21 arranged at the bottom of the first cavity 11. The upper fixing member 20 and the lower fixing member 21 are located in the space around the seed crystal to enclose a growth cavity 25, and the width of the growth cavity 25 gradually increases along the direction approaching the second cavity 12; the raw material area 30 is arranged in a circle away from the growth cavity 25 in the second cavity 12; the graphite cylinder 40 is arranged on the inner periphery of the raw material area 30, and the graphite cylinder 40 is provided with an opening; the heat preservation structure 50 is arranged on the outer periphery of the crucible 10, and the heat preservation structure 50 has a through hole 51 corresponding to the temperature measuring tank 13.

[0024] The specific growth process of the silicon carbide single crystal growth device provided in this embodiment is: the seed crystal is fixed between the upper fixing member 20 and the lower fixing member 21, and the crucible 10 is heated by arranging a heater on the periphery of the growth device of this embodiment. During the heating process, the raw material sublimates to produce gaseous substances including Si, Si2C, SiC2, etc. These gaseous substances are transmitted to the seed crystal with lower temperature under the drive of the temperature gradient after passing through the graphite cylinder 40, and grow into a silicon carbide single crystal through a solid-gas-solid reaction.

[0025] It should be noted that the crucible 10 can be heated by induction or resistance heating.

[0026] Compared with the prior art, the cross-sections of the first cavity 11 and the second cavity 12 of the crucible 10 in the growth device for silicon carbide single crystal of the present invention are H-shaped, and the heating area of ​​the entire growth device or the area directly receiving the heat radiation of the heater is the outer peripheral side wall of the crucible 10, and the second cavity 12 corresponding to the outer peripheral side wall has a larger local electromagnetic induction or heat radiation receiving area, which is convenient for efficient heating to meet the sublimation of silicon carbide powder (raw material); and the second cavity 12 can ensure a larger loading space, avoid the temperature increase of the cost of insulation materials caused by the expansion of the outer diameter of the crucible 10, and also avoid the problem of crystallization of the material surface caused by the larger radial thickness of the raw material; the top and bottom of the crucible 10 are provided with temperature measuring grooves 13, which can ensure the position of temperature measurement The device is placed closer to the first cavity 11, so that the temperature measurement value can accurately reflect the axial temperature gradient of the growth cavity 25, which is convenient for controlling the axial temperature gradient of the growth cavity 25 and reducing the risk of polycrystalline deposition in the growth cavity 25; the width of the growth cavity 25 in the direction close to the second cavity 12 gradually increases, and the isotherms of the growth cavity 25 can be modulated to have a convex shape in the middle, thereby reducing the risk of adhesion between the seed crystal and the upper fixture 20 or the lower fixture 21 during the growth process; the traditional growth mainly relies on the axial temperature gradient. The seed crystal in the growth device of the present invention grows sideways, and the growth direction is perpendicular to the dislocation line of the threading dislocation in the seed crystal, so as to avoid the replication of the threading dislocation and effectively avoid the threading dislocation from extending into the growing single crystal.

[0027] In some embodiments, a specific implementation of the upper fixing member 20 and the lower fixing member 21 can be as follows: Figure 1 and Figure 3 See the structure shown. Figure 1 and Figure 3 The upper fixing member 20 and the lower fixing member 21 each include a graphite sheet 22, an insertion rod 23 and a fixing plate 24. The graphite sheet 22 is fixedly connected to the top wall or the bottom wall in the first cavity 11. The middle of the graphite sheet 22 has a mounting hole. The top surface of the graphite sheet 22 is recessed to form a cylindrical cavity coaxial with the mounting hole. The diameter of the cavity is larger than the diameter of the mounting hole. The insertion rod 23 is matched with the mounting hole. The fixing plate 24 is fixedly connected to one end of the insertion rod 23 facing the seed crystal. The diameters of the fixing plate 24 and the cavity are both smaller than the diameter of the seed crystal, and the bottom surface of the graphite sheet 22 in the upper fixing member 20 and the top surface of the graphite sheet 22 in the lower fixing member 21 enclose a growth cavity 25 .

[0028] The mounting hole in the upper fixing member 20 is located between the top wall of the first cavity 11 and the cavity, and the mounting hole in the lower fixing member 21 is located between the bottom wall of the first cavity 11 and the cavity. Since the mounting holes have a certain depth, by inserting the insertion rod 23 into the mounting hole, when the seed crystal is loaded between the two fixing disks 24, the interval between the two fixing disks 24 can be adjusted, thereby ensuring that the error of the axial size of the seed crystal is adapted.

[0029] In a specific implementation, the fixed disk 24 and the insertion rod 23 are an integrated structure, and the fixed disk 24, the insertion rod 23, and the graphite sheet 22 are all made of isostatic graphite. The fixed disk 24 is used to install the seed crystal, and the upper and lower end faces of the seed crystal after installation are fixed on the fixed disk 24, which can prevent the upper and lower end faces of the seed crystal from growing.

[0030] In some embodiments, an improved implementation of the first cavity 11 can be as follows: Figures 1 to 3 See the structure shown. Figures 1 to 3 The top wall and the bottom of the first cavity 11 are both provided with a limiting ring 14, and the graphite sheet 22 is snap-fitted to the inner ring of the limiting ring 14. After the graphite sheet 22 is installed, it is limited by the limiting ring 14 to prevent the installed graphite sheet 22 from sliding and changing its position, ensuring that the graphite sheet 22 is located at the center of the first cavity 11, and also ensuring that the position of the seed crystal is located at the center of the first cavity 11, so that the distance between the outer peripheral surface of the seed crystal and the raw material area 30 is consistent, thereby improving the growth quality of the seed crystal.

[0031] In some embodiments, an improved implementation of the upper fixing member 20 and the lower fixing member 21 can be as follows: Figure 1 and Figure 3 See the structure shown. Figure 1 and Figure 3 , the diameter of the fixed disk 24 is smaller than the diameter of the cavity. A gap is formed between the outer circumference of the fixed disk 24 and the inner circumference of the cavity to ensure that the cavity is connected to the growth cavity 25 to form an escape channel. During the growth of the seed crystal, the growth material on the outer circumference of the seed crystal will not only grow along the radial direction of the seed crystal, but also partially enter the escape channel, which can ensure the growth quality of the outer circumference of the seed crystal near the top edge and the bottom edge.

[0032] In some embodiments, a specific implementation of the above-mentioned thermal insulation structure 50 can be as follows: Figure 1 See the structure shown. Figure 1 The insulation structure 50 includes an outer insulation layer 52 and an inner insulation layer 53. The outer insulation layer 52 is wrapped around the outer periphery of the crucible 10. The outer insulation layer 52 corresponds to the second cavity 12 of the crucible 10. The top and bottom of the outer insulation layer 52 are respectively provided with temperature measuring holes corresponding to the temperature measuring grooves 13; the inner insulation layer 53 is respectively provided on the side walls of the two temperature measuring grooves 13, and the inner diameter of the inner insulation layer 53 is smaller than the diameter of the temperature measuring hole. By dividing the insulation structure 50 into the outer insulation layer 52 and the inner insulation layer 53, the temperature gradient of the raw material area 30 and the growth cavity 25 can be optimized by adjusting the thickness of the inner insulation layer 53. For details, see Figure 2 By adjusting the thickness of the inner insulation layer 53, the radial temperature gradient in region A can be reduced, thereby reducing the crystallization risk in region a; the axial temperature gradient in region B can also be reduced, thereby reducing the crystallization risk in region b; the radial temperature gradient in the growth chamber 25 is increased, thereby increasing the growth momentum of the seed crystal in the growth chamber 25.

[0033] By controlling the temperature gradient in the A region, the B region and the growth chamber 25, unnecessary polycrystalline deposition can be avoided, and effective transport of components and normal growth of seed crystals can be achieved.

[0034] Optionally, both the outer insulation layer 52 and the inner insulation layer 53 may be made of insulation carbon felt.

[0035] Specifically, the greater the thickness of the inner thermal insulation layer 53 is, the greater the temperature gradient in the axial direction of the growth chamber 25 is. Therefore, the thickness of the inner thermal insulation layer 53 is controlled to be above 10 mm.

[0036] In some embodiments, a specific design standard of the above-mentioned insulation structure 50 is that the wall thickness of the outer insulation layer 52 located at the top and bottom of the crucible 10 is equal, and the ratio of the wall thickness of the insulation layer located at the top of the crucible 10 to the wall thickness of the outer periphery of the crucible 10 is greater than 3:1.

[0037] By adjusting the thickness of the outer insulation layer 52 at the top and bottom of the crucible 10, and combining the adjustment of the thickness of the inner insulation layer 53, the axial temperature gradient in the crucible 10 can be adjusted, thereby controlling the probability of the seed crystal adhering to the side wall of the growth chamber 25. The axial temperature gradient in the center area of ​​the seed crystal is as close to 0 as possible, in order to ensure the axial symmetry of the crystal growth process and to reduce the adhesion between the well body and the inner wall of the growth chamber 25. The axial temperature gradient adjustment method of the seed crystal area is to control the deviation of the measured temperature in the upper and lower temperature measuring tanks 13 to be less than 10°C, and the temperature range is between 1800°C and 2150°C. At the same time, the axial temperature gradient of the growth chamber 25 is also related to the opening angle of the growth chamber 25. The top surface of the growth chamber 25 (i.e., the bottom surface of the graphite sheet 22 in the upper fixing member 20) gradually tilts upward in the direction close to the second cavity 12, and the bottom surface of the growth chamber 25 (i.e., the top surface of the graphite sheet 22 in the lower fixing member 21) gradually tilts downward in the direction close to the second cavity 12. The angle between the top surface and the bottom surface of the growth chamber 25 is the opening angle. An opening angle that is too large or too small is not conducive to suppressing the occurrence of polycrystalline adhesion, so the opening angle should be controlled between 5° and 20°.

[0038] By adjusting the thickness of the outer insulation layer 52 located at the outer peripheral part of the crucible 10, the radial temperature gradient in the crucible 10 can be adjusted, thereby controlling the growth of the seed crystal in the radial direction. The radial temperature gradient in the crucible 10 involves the radial temperature gradient of the growth chamber 25 and the raw material area 30. The radial temperature gradient is the driving force for the growth of the seed crystal. The temperature difference between the outer peripheral surface of the seed crystal and the surface of the raw material is between 20°C and 60°C.

[0039] In some embodiments, a specific design standard of the crucible 10 is that the height ratio of the second cavity 12 to the first cavity 11 is 3:2 to 4:1. The outer shape and the internal cavity shape of the crucible 10 are both H-shaped, and the height ratio of the second cavity 12 to the first cavity 11 is conducive to the control of system heat dissipation, raw material loading and temperature gradient, and is conducive to the normal growth of single crystals.

[0040] Based on the same inventive concept, see Figure 4 The present application also provides a silicon carbide single crystal growth device, which uses the silicon carbide single crystal growth device and includes the following steps: S10: Take an initial seed crystal 60, which is a columnar structure, and fix the initial seed crystal 60 between the upper fixing member 20 and the lower fixing member 21; S20: Waiting for the initial seed crystal 60 to grow for a preset time, and forming an annular growth zone on the periphery of the initial seed crystal 60; S30: removing the initial seed crystal 60 with the growth zone, and digging out the columnar growth seed crystal 70 in the growth zone; S40: Fixing the growth seed crystal 70 between the upper fixture 20 and the lower fixture 21 until a whole ingot of silicon carbide single crystal is grown.

[0041] Compared with the prior art, the silicon carbide single crystal growth method provided in the present embodiment is that an initial seed crystal 60 is grown on its periphery to form a growth zone, and then a columnar growth seed crystal 70 is dug out in the growth zone. The growth seed crystal 70 is then used to grow a whole ingot of silicon carbide single crystal in the same manner. The whole ingot of silicon carbide single crystal can be used as a production material for power devices, thereby improving the performance and reliability of the power devices.

[0042] It should be noted that the initial seed crystal 60 selected in this invention is a short cylindrical seed crystal having two upper and lower flat end faces and a cylindrical surface on the outer periphery. The upper and lower end faces are the installation and fixing surfaces of the seed crystal, and the cylindrical surface is a polished surface, which is used for the subsequent growth process of the crystal to grow along the radial direction of the short cylindrical seed crystal.

[0043] A too low seed crystal height will cause the growth chamber 25 to be too flat, which is not conducive to maintaining a stable growth interface. When growing crystals of the same diameter, a too large seed crystal height will require too much raw material loading. The height of the short cylindrical seed crystal in this embodiment is between 5-15 mm.

[0044] In some embodiments, an improved implementation of the above-mentioned silicon carbide single crystal growth method is: Before step S10, it also includes: The upper and lower end surfaces of the initial seed crystal 60 are coated with a corrosion-resistant coating.

[0045] Since the upper and lower end surfaces of the initial seed crystal 60 are installation and fixing surfaces, after being coated with a dense corrosion-resistant coating, sublimation negative growth can be prevented from occurring on the two end surfaces of the initial seed crystal 60 .

[0046] As an example, a specific step of the silicon carbide single crystal growth method provided in the embodiment of the present application is: It is mainly used in the field of growing 4-H silicon carbide crystals not less than 6 inches.

[0047] (1) In the first step of non-carbon surface growth, the height ratio between the second cavity 12 and the first cavity 11 of the selected H-type isostatic graphite crucible 10 is 2. Silicon carbide powder is placed in the raw material area 30 of the H-type isostatic graphite crucible 10, with a loading amount of 2000 g.

[0048] (2) A seed crystal is placed between the upper fixing member 20 and the lower fixing member 21 of an H-type isostatic graphite crucible 10. The seed crystal has a thickness of 7 mm and a diameter of 30 mm. The opening angle of the growth chamber 25 is 10°.

[0049] (3) The thickness of the inner insulation layer 53 is selected to be 20 mm, and the ratio of the thickness of the outer insulation layer 52 located at the top of the crucible 10 to the thickness located at the outer peripheral surface of the crucible 10 is 4:1. The thermal field assembly is completed.

[0050] (4) In the crystal growth stage, the process gas is purified argon with a pressure of 2000 Pa; the upper and lower temperature measurements are controlled at around 2100°C, with a difference of less than 10°C.

[0051] (5) After the first step of non-carbon surface growth is completed, a 30 mm diameter area is taken from the non-carbon surface growth area of ​​the obtained crystal ingot and processed into a seed crystal for the second step of non-carbon surface growth. The seed crystal has a thickness of 7 mm.

[0052] (6) Repeat steps (1) to (4) to obtain a silicon carbide single crystal grown on the non-carbon surface of the entire ingot.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A silicon carbide single crystal growth device, characterized in that: include: A crucible, comprising a first cavity located in the center and a second cavity located outside the first cavity, the first cavity and the second cavity are connected, the top surface of the second cavity is higher than the top surface of the first cavity, and the bottom surface is lower than the bottom surface of the first cavity, the top and bottom of the crucible are both recessed to form temperature measuring grooves, and the two temperature measuring grooves are located at the top and bottom of the first cavity; A seed crystal fixing assembly, comprising an upper fixing member disposed at the top of the first cavity and a lower fixing member disposed at the bottom of the first cavity, wherein the space around the seed crystal formed by the upper fixing member and the lower fixing member encloses a growth cavity, and the width of the growth cavity gradually increases in a direction approaching the second cavity; A raw material area, arranged in a circle in the second cavity away from the growth cavity; A graphite cylinder is arranged on the inner periphery of the raw material area, and the graphite cylinder is provided with an opening; The heat-insulating structure is arranged on the outer periphery of the crucible, and the heat-insulating structure has a through hole corresponding to the temperature measuring tank.

2. The silicon carbide single crystal growth apparatus according to claim 1, wherein: The upper fixing member and the lower fixing member both include: A graphite sheet is fixedly connected to the top wall or the bottom wall in the first cavity, the middle of the graphite sheet has a mounting hole, the top surface of the graphite sheet is recessed to form a cylindrical cavity coaxial with the mounting hole, and the diameter of the cavity is larger than the diameter of the mounting hole; An insertion rod, matched with the mounting hole; A fixed plate, fixedly connected to one end of the insertion rod facing the seed crystal; The diameters of the fixing plate and the cavity are both smaller than the diameter of the seed crystal, and the bottom surface of the graphite sheet in the upper fixing member and the top surface of the graphite sheet in the lower fixing member enclose the growth cavity.

3. The silicon carbide single crystal growth apparatus according to claim 2, wherein: The top wall and the bottom of the first cavity are both provided with limiting rings, and the graphite sheet is snap-fitted to the inner ring of the limiting ring.

4. The silicon carbide single crystal growth apparatus according to claim 2, wherein: The diameter of the fixing disk is smaller than the diameter of the cavity.

5. The silicon carbide single crystal growth apparatus according to claim 1, wherein: The thermal insulation structure comprises: An outer insulation layer is wrapped around the outer circumference of the crucible, the outer insulation layer corresponds to the second cavity of the crucible, and the top and bottom of the outer insulation layer are respectively provided with temperature measuring holes corresponding to the temperature measuring tank; The inner thermal insulation layer is respectively arranged on the side walls of the two temperature measuring grooves, and the inner diameter of the inner thermal insulation layer is smaller than the diameter of the temperature measuring hole.

6. The silicon carbide single crystal growth apparatus according to claim 5, wherein: The thickness of the inner thermal insulation layer is greater than 10 mm.

7. The silicon carbide single crystal growth apparatus according to claim 5, wherein: The wall thickness of the outer insulation layer at the top and bottom of the crucible is equal, and the ratio of the wall thickness of the insulation layer at the top of the crucible to the wall thickness of the insulation layer at the periphery of the crucible is greater than 3:

1.

8. The silicon carbide single crystal growth apparatus according to claim 1, wherein: The height ratio of the second cavity to the first cavity is 3:2-4:

1.

9. A method for growing a silicon carbide single crystal, characterized in that: The silicon carbide single crystal growth device according to any one of claims 1 to 8 comprises the following steps: S10: taking an initial seed crystal, wherein the initial seed crystal is a columnar structure, and fixing the initial seed crystal between the upper fixing member and the lower fixing member; S20: Waiting for the initial seed crystal to grow for a preset time, and forming an annular growth zone on the periphery of the initial seed crystal; S30: removing the initial seed crystal with the growth zone, and digging out the columnar growth seed crystal in the growth zone; S40: Fixing the growth seed crystal between the upper fixture and the lower fixture until a whole ingot of silicon carbide single crystal is grown.

10. The method for growing a silicon carbide single crystal according to claim 9, wherein: Before the step S10, the following steps are also included: A corrosion-resistant coating is applied to the upper and lower end surfaces of the initial seed crystal.

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