Silicon carbide crystal growth method and device and silicon carbide crystal

Abstract

The embodiment of the invention provides a silicon carbide crystal growth method and device and a silicon carbide crystal, and relates to the technical field of silicon carbide crystal growth. The technical problem that in the prior art, due to the fact that a crystal growth process lacks guidance on a gas phase in an ascending stage, the quality of silicon carbide crystals is affected is solved. The silicon carbide crystal growth method comprises the following steps: arranging seed crystals and silicon carbide powder in a crucible, and arranging a hyperbolic plate assembly in the crucible; pumping air from the crucible, filling inert gas, and heating the crucible to enable the silicon carbide crystals to enter a growth stage; and in the crystal growth stage, the flow direction of the gas phase in the rising stage in the crucible is guided through the hyperbolic plate assembly until the growth of the silicon carbide crystal is finished. Through the hyperbolic plate assembly arranged in the crucible, gas phase flow directions in different rising stages in the crucible are guided, so that the crystal growth rate is increased, the dislocation density is reduced, and the crystal yield is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide crystal growth, and more particularly, to a method and apparatus for growing silicon carbide crystals and a silicon carbide crystal. Background Art

[0002] As a representative of the third-generation semiconductor materials, silicon carbide has excellent properties such as a large bandgap, a high saturated electron mobility, a high breakdown electric field, and a high thermal conductivity, and is widely used in the fields of power electronics, radio frequency devices, optoelectronic devices, etc.

[0003] In the existing silicon carbide crystal growth apparatus and process, the porous graphite plate used in the crystal growth apparatus is usually a flat plate. Due to the lack of guidance for the gas phase in the rising stage, problems such as central accumulation of gas phase substances and large radial temperature differences are likely to occur, thereby affecting the quality of silicon carbide crystals. Summary of the Invention

[0004] The objectives of the present invention include providing a method and apparatus for growing silicon carbide crystals and a silicon carbide crystal to improve the technical problem in the existing crystal growth process that the quality of silicon carbide crystals is affected due to the lack of guidance for the gas phase in the rising stage.

[0005] Embodiments of the present invention may be implemented as follows: In a first aspect, the present invention provides a method for growing silicon carbide crystals, including: Setting a seed crystal and silicon carbide powder in a crucible, and arranging a hyperbolic plate assembly in the crucible; Evacuating the crucible and then filling it with an inert gas, and heating the crucible to enable the silicon carbide crystal to enter the growth stage; During the crystal growth stage, guiding the flow direction of the gas phase in the rising stage in the crucible through the hyperbolic plate assembly until the growth of the silicon carbide crystal ends.

[0006] In an optional embodiment, the rising stage includes: A first rising stage, where the gas phase diffuses from the lower chamber towards the upper chamber and contacts the second curved surface baffle; A second rising stage, where the gas phase passes through the second curved surface baffle and diffuses into the drum-shaped cavity; A third rising stage, where the gas phase diffuses in the drum-shaped cavity towards the upper crucible and contacts the first curved surface baffle; A fourth rising stage, where the gas phase passes through the first curved surface baffle and diffuses towards the upper chamber until it reaches the seed crystal.

[0007] In an optional embodiment, the method for guiding the flow direction of the gas phase in the rising stage in the crucible through the hyperbolic plate assembly includes: During the first ascending stage, the gas phase contacts the concave surface portion, and under the action of the concave surface portion, the gas phase diffuses radially outward; During the third ascending stage, the gas phase contacts the convex surface portion, and under the action of the convex surface portion, the gas phase diffuses radially inward; meanwhile, a controllable turbulence is formed at the central portion of the convex surface portion.

[0008] In a second aspect, the present invention provides a silicon carbide crystal growth apparatus, comprising: A crucible, the crucible comprising an upper crucible and a lower crucible, and a chamber is formed between the upper crucible and the lower crucible; A hyperbolic plate assembly, the hyperbolic plate assembly is disposed in the chamber and divides the chamber into an upper chamber for fixing a seed crystal and a lower chamber for accommodating silicon carbide powder.

[0009] In an optional embodiment, the hyperbolic plate assembly comprises a first curved surface baffle and a second curved surface baffle for guiding the gas flow direction; A drum-shaped cavity for the gas phase to flow is formed between the first curved surface baffle and the second curved surface baffle.

[0010] In an optional embodiment, the outer edge of the first curved surface baffle is connected to the inner wall of the crucible, and protrudes toward the side close to the upper chamber to form a convex surface portion; a plurality of first through holes for the gas phase to pass through are formed on the convex surface portion; The outer edge of the second curved surface baffle is connected to the inner wall of the crucible, and protrudes toward the side close to the lower chamber to form a concave surface portion; a plurality of second through holes for the gas phase to pass through are formed on the concave surface portion.

[0011] In an optional embodiment, both the convex surface portion and the concave surface portion are spherical surfaces, and the radius of curvature of the convex surface portion is And the radius of curvature of the concave surface portion Are respectively:

[0012]

[0013] Wherein, Is the radius of curvature of the inner wall of the crucible.

[0014] In an optional embodiment, the distance between the outer edge of the first curved surface baffle and the outer edge of the second curved surface baffle Is:

[0015] Wherein, Is the loading height of the silicon carbide powder.

[0016] In an optional embodiment, both the first through holes and the second through holes are arranged in an annular array.

[0017] In a third aspect, the present invention provides a silicon carbide crystal, which is prepared by using the silicon carbide crystal growth method described in any one of the foregoing embodiments or the silicon carbide crystal growth apparatus described in any one of the foregoing embodiments.

[0018] The beneficial effects of the silicon carbide crystal growth method, apparatus and silicon carbide crystal provided by the embodiments of the present invention include: The silicon carbide crystal growth apparatus and growth method provided by the present invention guide the gas flow in different rising stages in the crucible through a hyperbolic plate assembly, thereby improving the quality of the silicon carbide crystal. Specifically, in terms of thermal field control, by guiding the gas phase, the radial temperature difference can be reduced and the retention of the gas phase in the hot zone can be avoided; in terms of hydrodynamics, by guiding the gas phase, the central accumulation of the gas phase can be avoided, and at the same time, controllable turbulence can be generated during the rising process of the gas phase to improve the mass transfer efficiency; in terms of stress elimination, the lattice distortion caused by the sudden drop in the edge temperature can be eliminated, and the interfacial laminar flow can be suppressed to avoid the dendritic growth caused by constitutional supercooling; in terms of defect suppression, the thermal stress can be homogenized to reduce the microtube density, and at the same time, the formation of large-sized vacancy clusters can be suppressed by the controllable turbulence perturbation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 is a flowchart of the silicon carbide crystal growth method provided by the present invention; Figure 2 is a schematic structural diagram of the silicon carbide crystal growth apparatus provided by the present invention.

[0021] Reference numerals: 100 - crucible; 110 - upper crucible; 120 - lower crucible; 130 - chamber; 131 - upper chamber; 132 - lower chamber; 140 - seed crystal; 150 - silicon carbide powder. 200 - hyperbolic plate assembly; 210 - first curved surface baffle; 211 - convex portion; 212 - first through hole; 220 - second curved surface baffle; 221 - concave portion; 222 - second through hole; 230 - drum cavity. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Components of the embodiments of the present invention usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0024] It should be noted that like reference numerals and letters denote like 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 subsequent drawings.

[0025] In the description of the present invention, it should be noted that if terms such as "upper", "lower", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the products of the present invention are usually placed during use, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0026] In addition, terms such as "first", "second", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0027] It should be noted that, without conflict, the features in the embodiments of the present invention can be combined with each other.

[0028] The following details the steps, implementation principles, and achieved technical effects of the silicon carbide crystal growth method provided by the present invention through examples in combination with the accompanying drawings, as well as the overall structure, working principle, and achieved technical effects of the supporting silicon carbide crystal growth device.

[0029] Please refer to Figure 1 , this embodiment provides a silicon carbide crystal growth method, including the following steps: S1. Set a seed crystal 140 and silicon carbide powder 150 in the crucible 100, and set a hyperbolic plate assembly 200 in the crucible 100; S2. After evacuating the crucible 100, fill it with an inert gas, and heat the crucible 100 to make the silicon carbide crystal enter the growth stage; S3. During the crystal growth stage, the hyperbolic plate assembly 200 is used to guide the gas flow in the ascending stage in the crucible 100 until the growth of the silicon carbide crystal is completed.

[0030] The methods for setting the above seed crystal 140, the silicon carbide powder 150, and the heating method of the crucible 100 are similar to those in the prior art. The difference lies in that in the present invention, during the diffusion process of the gaseous substance towards the seed crystal 140, the flow direction is guided by the hyperbolic plate assembly 200, thereby avoiding the problem of affecting the quality of the silicon carbide crystal due to the accumulation of gaseous substances or a large radial temperature difference.

[0031] Specifically, the silicon carbide powder 150 is heated and sublimated to generate gaseous substances. During the diffusion process of the gaseous substances towards the seed crystal 140, according to the different positions relative to the hyperbolic plate assembly 200, it is divided into the following ascending stages: In the first ascending stage, the gas diffuses from the lower chamber 132 towards the upper chamber 131 and contacts the second curved surface baffle 220; at this time, the gas contacts the concave surface portion 221, so that the gas accumulated in the middle of the second curved surface baffle 220 diffuses radially outwards under the action of the concave surface portion 221, that is, towards the inner wall of the crucible 100.

[0032] In the second ascending stage, the gas passes through the second curved surface baffle 220 and diffuses into the drum-shaped cavity 230. In the third ascending stage, the gas diffuses in the drum-shaped cavity 230 towards the upper crucible 110 and contacts the first curved surface baffle 210; at this time, the gas contacts the convex surface portion 211. After the gas flow impacts the convex surface, a low-frequency Karman vortex street is generated on the leeward side, and the vortex slowly diffuses to the edge through tangential migration; microscopic vortices are generated on the convex surface to assist diffusion, so that the gas diffuses radially inwards and outwards under the action of the convex surface portion.

[0033] At the same time, the gas located at the center of the convex surface portion 211 has an accelerated flow rate under the convergence effect at the center of the convex surface portion 211 and forms a controllable turbulent flow. The formation of the controllable turbulent flow strengthens the rate of transportation of the gaseous substance to the growth interface and improves the mass transfer efficiency at the same time.

[0034] In the fourth ascending stage, the gas passes through the first curved surface baffle 210 and diffuses towards the upper chamber 131 until it reaches the seed crystal 140.

[0035] Furthermore, during the first ascending stage of the gaseous substance, under the action of the concave surface portion 221, the gas accumulated in the middle diffuses towards the inner wall of the crucible 100, which can avoid the accumulation of gas in the center while compensating for the heat loss at the edge and reducing the radial temperature difference.

[0036] In the third ascending stage, under the action of the convex surface portion 211, the gas phase at the center of the convex surface portion 211 accelerates upward, thereby forming a controllable turbulence, which can improve the mass transfer efficiency while suppressing the formation of large-sized vacancy clusters in the crystal.

[0037] The silicon carbide crystal growth method provided in this embodiment can at least produce the following technical effects: The silicon carbide crystal growth method provided in this embodiment can guide the gas phase flow directions at different ascending stages in the crucible 100, and can have beneficial effects on the crystal growth process and crystal quality in terms of thermal field control, hydrodynamics, stress elimination, and defect suppression; including that when the gas phase substance is in the first ascending stage, it can avoid the gas phase from accumulating in the center and reduce the radial temperature difference; when in the second ascending stage, it can make the gas phase substance form a controllable turbulence, thereby improving the mass transfer efficiency and suppressing the formation of large-sized vacancy clusters in the crystal.

[0038] Correspondingly, this embodiment provides a silicon carbide crystal growth device, which is based on the silicon carbide crystal growth method provided in Embodiment 1 and is mainly applied to the preparation of silicon carbide single crystal substrates based on the physical vapor transport method.

[0039] Please refer to Figure 2 , the silicon carbide crystal growth device provided in this embodiment includes a crucible 100 and a hyperbolic plate assembly 200 disposed in the crucible 100. Among them, the structure of the crucible 100 is similar to that of the prior art, including a separable upper crucible 110 and a lower crucible 120, and a chamber 130 is formed between the upper crucible 110 and the lower crucible 120.

[0040] Specifically, a hyperbolic plate assembly 200 is disposed in the chamber 130, and the hyperbolic plate assembly 200 divides the chamber 130 into an upper chamber 131 for fixing the seed crystal 140 and a lower chamber 132 for accommodating the silicon carbide powder 150.

[0041] The hyperbolic plate assembly 200 includes a first curved surface baffle 210 and a second curved surface baffle 220 for guiding the gas phase flow direction, and a drum-shaped cavity 230 for the gas phase to flow is formed between the first curved surface baffle 210 and the second curved surface baffle 220.

[0042] It should be noted that the first curved surface baffle 210 and the second curved surface baffle 220 exist independently of each other. In this embodiment, the first curved surface baffle 210 is disposed in the upper chamber 131 and connected to the upper crucible 110, and the second curved surface baffle 220 is disposed in the lower chamber 132 and connected to the lower crucible 120.

[0043] In multiple other embodiments, the first curved surface baffle 210 and the second curved surface baffle 220 can also be both disposed in the upper chamber 131 or both disposed in the lower chamber 132.

[0044] Further, the outer edge of the first curved surface baffle 210 is connected to the inner wall of the upper crucible 110, protrudes toward the side close to the upper chamber 131, and forms a convex surface portion 211; a plurality of first through holes 212 for allowing gas phase to pass through are annularly arrayed on the convex surface portion 211; the outer edge of the second curved surface baffle 220 is connected to the inner wall of the lower crucible 120, protrudes toward the side close to the lower chamber 132, and forms a concave surface portion 221; a plurality of second through holes 222 for allowing gas phase to pass through are annularly arrayed on the concave surface portion 221.

[0045] Further, the gas phase substance first contacts the concave surface portion 221 in the second curved surface baffle 220, passes through the concave surface portion 221 and the drum cavity 230, then contacts the convex surface portion 211 in the first curved surface baffle 210, and finally passes through the first curved surface baffle 210.

[0046] Please refer to Figure 2 , Figure 2 The arrow directions in [reference] indicate the flow directions of some gas phases; specifically, the concave surface portion 221 is a spherical surface. When the gas phase contacts the lower surface of the concave surface portion 221, part of the gas phase passes through the second through holes 222 and passes through the second curved surface baffle 220 into the drum cavity 230, and the other part of the gas phase diffuses along the radial direction toward the inner wall of the lower crucible 120 under the action of the concave surface portion 221, thus avoiding the accumulation of the gas phase at the center of the lower surface of the second curved surface baffle 220.

[0047] Similar to the concave surface portion 221, when the gas phase contacts the lower surface of the convex surface portion 211, part of the gas phase passes through the first through holes 212 and passes through the first curved surface baffle 210 into the upper chamber 131, and the other part of the gas phase generates low-frequency Karman vortex streets on the leeward side after hitting the lower surface of the convex surface portion 211, and the vortices slowly diffuse to the edge through tangential migration, so that the gas phase also diffuses along the radial direction toward the inner wall of the upper crucible 110 under the action of the convex surface portion 211. For the gas located at the center of the convex surface portion 211, under the action of the convex surface portion 211, the gas flow rate is increased, and finally a controllable turbulent flow is formed at the center position of the first curved surface baffle 210, thereby improving the mass transfer efficiency and suppressing the formation of large-size vacancy clusters in the crystal.

[0048] Further, the distance between the outer edge of the first curved surface baffle 210 and the outer edge of the second curved surface baffle 220 is:

[0049] wherein, is the charging height of the silicon carbide powder 150.

[0050] Specifically, the distance between the outer edge of the first curved surface baffle 210 and the outer edge of the second curved surface baffle 220 can be 0.10H c , 0.11 H c , 0.12 H c , 0.13 H c , 0.14 H c , 0.15 H c ; As the distance between the outer edge of the first curved surface baffle 210 and the outer edge of the second curved surface baffle 220 continuously decreases, the flow resistance in the drum cavity 230 increases accordingly; as the distance between the outer edge of the first curved surface baffle 210 and the outer edge of the second curved surface baffle 220 continuously increases, the vortex in the drum cavity 230 decays. Therefore, the distance between the outer edge of the first curved surface baffle 210 and the outer edge of the second curved surface baffle 220 should be within the above range.

[0051] Further, the radius of curvature of the convex surface portion 211 is and the radius of curvature of the concave surface portion 221 is respectively:

[0052]

[0053] Wherein, is the radius of curvature of the inner wall of the crucible 100.

[0054] Specifically, the radius of curvature of the convex surface portion 211 can be , , , ; the radius of curvature of the concave surface portion 221 can be , , , ; As the radius of curvature continuously decreases, the converging effect of the central part of the convex surface portion 211 on the gas phase increases, thereby increasing the gas phase flow rate and causing strong turbulent damage; as the radius of curvature continuously increases, the converging effect of the central part of the convex surface portion 211 on the gas phase decreases, thereby forming laminar flow inhibition; as the radius of curvature continuously decreases, the guiding effect of the concave surface portion 221 on the gas phase decreases, thereby causing heat accumulation of the gas phase at the central part of the second curved surface baffle 220; as the radius of curvature continuously increases, the guiding effect of the concave surface portion 221 on the gas phase increases, thereby causing supercooling of the gas phase at the edge of the second curved surface baffle 220 and increasing the radial temperature gradient.

[0055] Therefore, the radius of curvature of the convex surface portion 211 and the radius of curvature of the concave surface portion 221 should be limited within the above ranges.

[0056] Furthermore, the radius of curvature of the convex surface portion 211 is , and the radius of curvature of the concave surface portion 221 is .

[0057] In addition, when the radius of curvature of the convex surface portion 211 and the radius of curvature of the concave surface portion 221 are both within the above ranges, certain synergistic effects can be additionally generated on the basis of achieving their own effects, including: In terms of thermal field control, the gas phase, under the combined action of the first curved surface baffle 210 and the second curved surface baffle 220, improves the uniformity of the radial temperature; In terms of hydrodynamics, by guiding the gas phase flow direction and forming controllable turbulence, the mass transfer efficiency is improved; In terms of stress elimination, the anisotropy of the crystal stress is reduced.

[0058] In terms of defect suppression, the generation of macroscopic cracks in the crystal can be avoided.

[0059] A silicon carbide crystal growth device provided in this embodiment guides the gas phase flow direction at different rising stages in the crucible 100 by providing a hyperbolic plate assembly 200. Specifically, during the rising process of the gas phase, through the guidance of the concave surface portion 221, in terms of thermal field control, the radial temperature difference is reduced to avoid the retention of the gas phase hot zone. In terms of hydrodynamics, the concave surface portion 221 can guide the gas phase to diffuse outward along the curved surface, thereby avoiding central accumulation; in terms of stress elimination, the lattice distortion caused by the sudden drop in the edge temperature is eliminated; in terms of defect suppression, the thermal stress is made uniform, thereby reducing the crystal microtube density; through the guidance of the convex surface portion 211, in terms of thermal field control, the gas phase flow rate can be guided to increase, preventing the retention of the hot zone; in terms of hydrodynamics, by generating controllable turbulence in the gas phase, the transportation of gas phase substances to the growth interface is strengthened; in terms of stress elimination, the interfacial laminar flow can be suppressed to avoid dendritic growth caused by constitutional supercooling; in terms of defect suppression, by forming controllable turbulence, the formation of large-sized vacancy clusters is suppressed by turbulent perturbation.

[0060] Example 1: In this example, the radius of curvature of the convex surface portion 211 is , and the radius of curvature of the concave surface portion 221 is .

[0061] Example 2: This embodiment also provides a silicon carbide crystal growth device, whose overall structure, working principle and achieved technical effects are basically the same as those of the first embodiment. The difference is that in this embodiment, the radius of curvature of the convex surface portion 211 is , and the radius of curvature of the concave surface portion 221 is .

[0062] Embodiment Three: This embodiment also provides a silicon carbide crystal growth device, whose overall structure, working principle and achieved technical effects are basically the same as those of the first embodiment. The difference is that in this embodiment, the radius of curvature of the convex surface portion 211 is , and the radius of curvature of the concave surface portion 221 is .

[0063] Embodiment Four: This embodiment also provides a silicon carbide crystal growth device, whose overall structure, working principle and achieved technical effects are basically the same as those of the first embodiment. The difference is that in this embodiment, the radius of curvature of the convex surface portion 211 is , and the radius of curvature of the concave surface portion 221 is .

[0064] Comparative Example One: The difference between Comparative Example One and the embodiment is that in Comparative Example One, the radius of curvature of the convex surface portion 211 and the radius of curvature of the concave surface portion 221 are both 0, that is, a perforated flat graphite plate is used to replace the first curved surface baffle 210 and the second curved surface baffle 220.

[0065] Comparative Example Two: The difference between Comparative Example Two and the embodiment is that in Comparative Example Two, the radius of curvature of the convex surface portion 211 is 0, and the radius of curvature of the concave surface portion 221 is ; that is, a perforated flat graphite plate is used to replace the first curved surface baffle 210.

[0066] Comparative Example Three: The difference between Comparative Example Three and the embodiment is that in Comparative Example Three, the radius of curvature of the convex surface portion 211 is , and the radius of curvature of the concave surface portion 221 is 0; that is, a perforated flat graphite plate is used to replace the second curved surface baffle 220.

[0067] Comparative Example Four: The difference between Comparative Example 4 and the Example is that, in Comparative Example 4, the curvature radius of the convex surface portion 211 is , and the curvature radius of the concave surface portion 221 is ; that is, the first curved surface baffle 210 and the second curved surface baffle 220 are provided, but the curvature radii of the corresponding convex surface portion 211 and concave surface portion 221 are both smaller than the ranges given in Example 2.

[0068] Comparative Example 5: The difference between Comparative Example 5 and the Example is that, in Comparative Example 5, the curvature radius of the convex surface portion 211 is , and the curvature radius of the concave surface portion 221 is ; that is, the first curved surface baffle 210 and the second curved surface baffle 220 are provided, but the curvature radii of the corresponding convex surface portion 211 and concave surface portion 221 are both larger than the ranges given in Example 2.

[0069] The crystal growth conditions and crystal quality parameters of Examples 1 to 4 and Comparative Examples 1 to 5 were detected, and the results are shown in Table 1.

[0070] Table 1

[0071] Combined with Table 1, by comparing the Example with Comparative Example 1, it can be seen that setting the first curved surface baffle 210 and the second curved surface baffle 220 with the convex surface portion 211 and the concave surface portion 221 can effectively improve the crystal growth rate, reduce the dislocation density, and improve the crystal yield.

[0072] By comparing the Example with Comparative Examples 2 and 3, it can be seen that when only the first curved surface baffle 210 or only the second curved surface baffle 220 is provided, due to the lack of the synergistic effect of the first curved surface baffle 210 and the second curved surface baffle 220, the crystal growth rate is significantly reduced, the dislocation density is significantly increased, and the crystal yield is significantly reduced; therefore, through the synergistic effect of the first curved surface baffle 210 and the second curved surface baffle 220, the crystal growth rate can be effectively improved, the dislocation density can be reduced, and the crystal yield can be improved.

[0073] By comparing the Example with Comparative Examples 4 and 5, it can be seen that when the curvature radii of the convex surface portion 211 and the concave surface portion 221 are smaller than or larger than the failure boundary values, the growth rate is significantly reduced, the dislocation density is significantly increased, and the crystal yield is significantly reduced.

[0074] In summary, the silicon carbide crystal growth apparatus and method provided by the present invention with the curved hyperbolic plate assembly 200 can guide the gas flow directions at different rising stages in the crucible 100, thereby increasing the crystal growth rate, reducing the dislocation density, and improving the crystal yield.

[0075] The above is only a specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for growing a silicon carbide crystal, characterized in that, Comprising: A seed crystal (140) and silicon carbide powder (150) are arranged in a crucible (100), and a hyperbolic plate assembly (200) is arranged in the crucible (100); After evacuating the crucible (100), an inert gas is filled, and the crucible (100) is heated to enable the silicon carbide crystal to enter the growth stage; During the crystal growth stage, the gas flow direction in the ascending stage in the crucible (100) is guided by the hyperbolic plate assembly (200) until the growth of the silicon carbide crystal ends.

2. The silicon carbide crystal growth method according to claim 1, wherein The ascending stage includes: A first ascending stage, where the gas phase diffuses from the lower chamber (132) towards the upper chamber (131) and contacts the second curved surface baffle (220); A second ascending stage, where the gas phase passes through the second curved surface baffle (220) and diffuses into the drum-shaped cavity (230); A third ascending stage, where the gas phase diffuses in the drum-shaped cavity (230) towards the upper crucible (110) and contacts the first curved surface baffle (210); A fourth ascending stage, where the gas phase passes through the first curved surface baffle (210) and diffuses towards the upper chamber (131) until it reaches the seed crystal (140).

3. The silicon carbide crystal growth method according to claim 2, wherein, A method for guiding the gas flow direction in the ascending stage in the crucible (100) by the hyperbolic plate assembly (200) includes: During the first ascending stage, the gas phase contacts the concave surface portion (221), and the gas phase diffuses radially outwards under the action of the concave surface portion (221); During the third ascending stage, the gas phase contacts the convex surface portion (211), and the gas phase diffuses radially outwards under the action of the convex surface portion (211); meanwhile, a controllable turbulent flow is formed at the central portion of the convex surface portion (211).

4. A silicon carbide crystal growth apparatus, characterized in that, Comprising: A crucible (100), the crucible (100) includes an upper crucible (110) and a lower crucible (120), and a chamber (130) is formed between the upper crucible (110) and the lower crucible (120); A hyperbolic plate assembly (200), the hyperbolic plate assembly (200) is arranged in the chamber (130) and divides the chamber (130) into an upper chamber (131) for fixing the seed crystal (140) and a lower chamber (132) for accommodating the silicon carbide powder (150).

5. The silicon carbide crystal growth apparatus according to claim 4, wherein The hyperbolic plate assembly (200) includes a first curved surface baffle (210) and a second curved surface baffle (220) for guiding the gas flow direction; A drum-shaped cavity (230) for the gas phase to flow is formed between the first curved surface baffle (210) and the second curved surface baffle (220).

6. The silicon carbide crystal growth apparatus according to claim 5, wherein, The outer edge of the first curved surface baffle (210) is connected to the inner wall of the crucible (100), and protrudes towards the side close to the upper chamber (131) to form a convex surface portion (211); a plurality of first through holes (212) for the gas phase to pass through are formed on the convex surface portion (211); The outer edge of the second curved surface baffle (220) is connected to the inner wall of the crucible (100), and protrudes towards the side close to the lower chamber (132) to form a concave surface portion (221); a plurality of second through holes (222) for the gas phase to pass through are formed on the concave surface portion (221).

7. The silicon carbide crystal growth apparatus according to claim 6, wherein, Both the convex surface portion (211) and the concave surface portion (221) are spherical surfaces, and the radius of curvature of the convex surface portion (211) is and the radius of curvature of the concave surface portion (221) are respectively: Wherein, is the radius of curvature of the inner wall of the crucible (100).

8. The silicon carbide crystal growth device according to claim 5, characterized in that The distance between the outer edge of the first curved baffle (210) and the outer edge of the second curved baffle (220) is Wherein, is the charging height of the silicon carbide powder material (150).

9. The silicon carbide crystal growth apparatus according to claim 6, characterized in that, The first through holes (212) and the second through holes (222) are both arranged in an annular array.

10. A silicon carbide crystal, characterized in that, Prepared by using the silicon carbide crystal growth method described in any one of claims 1-3 or the silicon carbide crystal growth apparatus described in any one of claims 4-9.

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