Growth device and method of silicon carbide crystal

Abstract

The invention discloses a growth device and method of silicon carbide crystals, the device comprises a growth crucible and a doping mechanism, the growth crucible comprises a crucible body and a crucible cover, the crucible body defines a containing cavity with an open top, the crucible cover is installed at the top of the crucible body, and seed crystals are arranged at the bottom of the crucible cover; the doping mechanism is arranged in the containing cavity, silicon nitride powder is contained in the doping mechanism, and the doping mechanism has a first state and a second state and can be switched between the first state and the second state; in the first state, the doping mechanism is in a sealed state; in the second state, the doping mechanism is in an at least partially open state. According to the method, doping of the nitrogen element and the silicon element can be achieved, the nitrogen element can effectively reduce the resistivity of silicon carbide, the silicon element can react with the carbon element to generate silicon carbide, generation of carbon wrapping is reduced, and the quality of silicon carbide crystals is improved.

Description

Technical Field

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

[0002] According to the different electrical properties, silicon carbide substrates can be divided into two categories: conductive silicon carbide substrates and semi-insulating silicon carbide substrates. These two types of substrates are used to manufacture discrete devices such as power devices and radio frequency devices after epitaxial growth. Among them, conductive silicon carbide substrates are mainly used in high-power and high-voltage fields such as new energy vehicles, high-speed rail transportation or power grid inverters. The existing methods for preparing conductive silicon carbide substrates mainly include physical vapor transport, chemical vapor transport, high-temperature solution method, etc.

[0003] At present, the physical vapor transport method (PhySiCal Vapor Transport, PVT) is one of the most commonly used methods. Its principle is: the silicon carbide powder in the crucible is heated. When its temperature reaches above 2100℃, the silicon carbide powder is heated and sublimated and deposited and grown on the silicon carbide seed crystal on the crucible cover. At the same time, N2 is introduced to dope the N element, thereby successfully growing a resistivity of 0.015~0.025Ω / cm 2 Conductive silicon carbide crystals. However, in actual operation, this method has the following defects:

[0004] First, the concentration of N2 in the crucible directly affects the resistivity of the silicon carbide crystal produced;

[0005] Second, when N2 flows, it will drive some carbon elements into the crystal, causing defects such as micropipes and screw dislocations. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention is to propose a growth device for silicon carbide crystals, which can achieve doping of nitrogen and silicon elements, wherein the nitrogen element can effectively reduce the resistivity of silicon carbide, and the silicon element can react with the carbon element to generate silicon carbide, reduce the generation of carbon encapsulation, and improve the quality of silicon carbide crystals.

[0007] The growth device of silicon carbide crystal according to the present invention comprises:

[0008] A growth crucible, the growth crucible comprising a crucible body and a crucible cover, the crucible body defining a receiving cavity with an open top, the crucible cover being mounted on the top of the crucible body, and a seed crystal being mounted on the bottom of the crucible cover;

[0009] A doping mechanism, wherein the doping mechanism is disposed in the accommodating cavity, the doping mechanism is filled with silicon nitride powder, the doping mechanism has a first state and a second state, and can be switched between the first state and the second state; in the first state, the doping mechanism is in a sealed state; in the second state, the doping mechanism is in an at least partially open state.

[0010] According to the silicon carbide crystal growth device of the present invention, by adding a doping mechanism in the growth crucible, the silicon nitride powder in the doping mechanism can be decomposed by heat during the crystal growth process, and by adjusting the doping mechanism, the nitrogen and silicon elements in the growth crucible can be supplemented at different stages of crystal growth. In the early stage of crystal growth, nitrogen elements will be doped into the growing silicon carbide crystal to achieve the doping of nitrogen elements in the silicon carbide crystal. The doping of nitrogen elements can effectively reduce the resistivity of silicon carbide to obtain a guided silicon carbide crystal; at the same time, the airflow formed by nitrogen elements can promote the sublimation of the silicon carbide powder above, and can also drive the sublimated silicon carbide vapor to move in the direction of the seed crystal, thereby accelerating the growth rate of the crystal. In the middle and late stages of crystal growth, the concentration of nitrogen elements decomposed in the late doping mechanism is low, so the doping mechanism is controlled to continue to open to the second state at a faster speed, accelerating the sublimation rate of nitrogen elements and silicon elements in the doping mechanism, so that the concentration of nitrogen elements in the growth crucible remains unchanged, so as to control the resistivity of the silicon carbide crystal in the late stage of crystal growth to remain unchanged. At the same time, the opening is enlarged at a faster speed, which can accelerate the sublimation of silicon elements in the doping mechanism into the growth crucible to supplement the concentration of silicon elements in the growth crucible. On the one hand, the supplemented silicon elements can generate silicon carbide with carbon elements for growth; on the other hand, it can reduce the entry of C clusters into the crystal, thereby reducing the generation of defects such as C packaging and micropipes. In addition, the doping mechanism can also be used as a heat source to further heat the silicon carbide powder, so that the silicon carbide powder is heated more evenly and sublimated more evenly, thereby improving the utilization rate of the silicon carbide powder.

[0011] In some embodiments of the present invention, the doping mechanism comprises:

[0012] A support rod, the support rod being rotatably mounted in the crucible body;

[0013] A power mechanism, the power mechanism is disposed outside the crucible body and connected to the support rod;

[0014] A doping unit, wherein there are a plurality of the doping units, and the plurality of the doping units are sleeved on the support rod at intervals;

[0015] Wherein, the silicon nitride powder is loaded in the doping unit, in the first state, the doping unit is in a sealed state; in the second state, the doping unit is in an at least partially open state; under the action of the power mechanism and the support rod, the doping unit switches between the first state and the second state.

[0016] In some embodiments of the present invention, the doping unit comprises:

[0017] A storage box, wherein the storage box is formed with a hollow cavity, an upper opening and a lower opening communicating with the hollow cavity are provided at the center of the storage box, and a top wall of the storage box is provided with a plurality of upper through holes communicating with the hollow cavity;

[0018] A sealing assembly, wherein the sealing assembly is disposed in the hollow cavity so that the upper through hole is completely blocked or at least partially exposed;

[0019] Wherein, the storage box is mounted on the support rod, and the sealing assembly is inserted on the support rod. When the support rod rotates, the sealing assembly rotates synchronously with the support rod, and the storage box remains stationary or has a different rotation speed from that of the support rod.

[0020] In some embodiments of the present invention, all the upper through holes are arranged in multiple rows and columns in a tic-tac-toe pattern along the upper surface of the storage box, and the distance between any two adjacent upper through holes in each row is the same, and the distance between any two adjacent upper through holes in each column is the same.

[0021] In some embodiments of the present invention, the sealing assembly includes a first baffle, which is clamped on the support rod and arranged close to the top wall of the storage box; in the first state, the first baffle completely blocks all of the upper through holes; in the second state, the first baffle is at least partially separated from the upper through holes.

[0022] In some embodiments of the present invention, the bottom wall of the storage box is provided with a plurality of lower through holes connected to the hollow cavity; the sealing assembly also includes a second baffle, which is clamped on the support rod and arranged close to the bottom wall of the storage box; in the first state, the second baffle completely blocks all of the lower through holes; in the second state, the second baffle is at least partially separated from the lower through holes.

[0023] In some embodiments of the present invention, the storage box comprises:

[0024] A box body, wherein the box body defines a storage cavity with an open top;

[0025] A box cover, the box cover is detachably mounted on the top of the box body;

[0026] The upper opening is opened at the center of the box cover, the lower opening is opened at the center of the box body, and the upper through holes are opened on the box cover around the upper opening.

[0027] The present invention also proposes a method for growing silicon carbide crystals, which can achieve nitrogen doping during the crystal growth process and reduce carbon wrapping, ultimately obtaining crystals of better quality.

[0028] The method for growing silicon carbide crystal according to the present invention comprises:

[0029] At the beginning of crystal growth, controlling the doping mechanism to gradually switch from the first state to the third state at a first speed;

[0030] In the middle and late stages of crystal growth, controlling the doping mechanism to switch from the third state to the second state at a second speed;

[0031] The third state is between the first state and the second state, and the first speed is lower than the second speed.

[0032] In some embodiments of the present invention, the weight ratio of the silicon nitride powder to the silicon carbide powder in the growth crucible is 1:20 to 1:200.

[0033] In some embodiments of the present invention, the particle size of the silicon carbide powder is 20-40 meshes, and the particle size of the silicon nitride powder is 1-3 meshes.

[0034] According to the silicon carbide crystal growth method of the present invention, based on the above-mentioned silicon carbide crystal growth device, in the early stage of crystal growth, the doping mechanism is controlled to gradually switch from a first state to a third state between the first state and the second state at a first speed, so that the sublimated nitrogen element can be doped into the growing silicon carbide crystal, effectively reducing the resistivity of silicon carbide to obtain a guided silicon carbide crystal; at the same time, the airflow formed by the sublimated elements can promote the sublimation of the silicon carbide powder above, and can also drive the sublimated silicon carbide vapor to move in the direction of the seed crystal, thereby accelerating the growth rate of the crystal. In the middle and late stages of crystal growth, the doping mechanism is controlled to switch from the third state to the second state at a second speed greater than the first speed, and continues to open at a faster speed, thereby accelerating the sublimation speed of nitrogen and silicon elements in the doping mechanism, so that the concentration of nitrogen in the growth crucible remains unchanged, so as to control the resistivity of the silicon carbide crystal to remain unchanged in the late stages of crystal growth; at the same time, the opening is rapidly enlarged at a faster speed, which can accelerate the sublimation of silicon elements in the doping mechanism into the growth crucible to supplement the concentration of silicon elements in the growth crucible. On the one hand, the supplemented silicon elements can generate silicon carbide with carbon elements for growth; on the other hand, it can reduce the entry of C clusters into the crystal, thereby reducing the generation of defects such as C encapsulation and micropipes, and improving the quality of the crystal.

[0035] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of a device for preparing a single crystal silicon carbide growth device according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the present invention when silicon carbide powder and silicon nitride powder are not loaded;

[0038] Figure 3 It is a structural schematic diagram of the doping mechanism of the present invention;

[0039] Figure 4 is a schematic diagram of a doping unit of the present invention;

[0040] Figure 5 is a top view of the doping mechanism in a first state;

[0041] Figure 6 It is a schematic diagram when the doping mechanism is partially open;

[0042] Figure 7 It is a schematic diagram when the doping mechanism is fully open;

[0043] Figure 8 is a resistivity detection diagram of Example 1 of the present invention;

[0044] Fig. 9 is a resistivity detection diagram of Example 1 of the present invention;

[0045] Fig.10 is a resistivity detection diagram of Example 1 of the present invention;

[0046] Fig.11 is a resistivity detection diagram of Example 1 of the present invention;

[0047] Fig.12 This is a resistivity detection diagram of Example 1 of the present invention.

[0048] Reference numerals:

[0049] Silicon carbide crystal growth device 1000;

[0050] Doping mechanism 100;

[0051] Doping unit 10; lower opening 101; upper opening 102; upper through hole 103; lower through hole 104; storage box 11; hollow cavity 110; box body 111; box cover 112; storage cavity 113; sealing assembly 12; first baffle 121; second baffle 122;

[0052] Support rod 20;

[0053] Power mechanism 30;

[0054] Growth crucible 200; crucible body 201; crucible cover 202; containing chamber 203;

[0055] Seed crystal 300;

[0056] Silicon nitride powder 400;

[0057] Silicon carbide powder 500;

[0058] Induction coil 600. DETAILED DESCRIPTION

[0059] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0060] The disclosure below provides many different embodiments or examples to implement different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific processes and examples of materials, but those of ordinary skill in the art can be aware of the applicability of other processes and / or the use of other materials.

[0061] Reference below Figure 1-Figure 12 A silicon carbide crystal growth apparatus and method according to an embodiment of the present invention are described.

[0062] Reference Figures 1 to 7 As shown, according to the silicon carbide crystal growth device 1000 of the embodiment of the present invention, the whole growth device includes a growth crucible 200 and a doping mechanism 100, the growth crucible 200 includes a crucible body 201 and a crucible cover 202, the crucible body 201 defines a receiving chamber 203 with an open top, the crucible cover 202 is installed on the top of the crucible body 201, the bottom of the crucible cover 202 is equipped with a seed crystal 300, and the silicon carbide powder 500 is installed in the receiving chamber 203; the doping mechanism 100 is arranged in the receiving chamber 203, the doping mechanism 100 is equipped with silicon nitride powder 400, the doping mechanism 100 has a first state and a second state, and can switch between the first state and the second state; in the first state, the doping mechanism 100 is in a sealed state; in the second state, the doping mechanism 100 is in an at least partially open state. Among them, a heating component and a heat preservation structure can be set outside the growth crucible 200. The heating component can use an induction coil 600 to heat the growth crucible 200. The structure outside the growth crucible 200 is the prior art, which is not the focus of protection of the present invention, so it will not be described in detail here.

[0063] For example, refer to Figures 1 to 7 As shown, the doping mechanism 100 is provided with a material holding space. When in use, the doping mechanism 100 can be adjusted to an open state first to load the silicon nitride powder 400 into the doping mechanism 100; after loading, the doping mechanism 100 is adjusted to a sealed state, and the entire doping mechanism 100 is loaded into the growth crucible 200 for standby use. It should be noted that the entire doping mechanism 100 can be completely placed in the silicon carbide powder 500, and its position in the vertical direction is adjustable. The doping mechanism 100 can be a graphite part, which has high temperature resistance and can continue to transfer heat to its interior, so that the silicon nitride powder 400 inside is heated to the decomposition temperature and decomposed into elemental nitrogen and silicon, thereby realizing the supplementation of nitrogen and silicon elements. Of course, the doping mechanism 100 can be a tantalum carbide or tungsten carbide part.

[0064] It can be understood that according to the silicon carbide crystal growth device of the embodiment of the present invention, when growing crystals, the temperature of the crucible body 201 increases and heat can be transferred to the silicon carbide powder 500 inside it to sublime it, and the sublimated silicon carbide vapor moves to the crucible cover 202 under the action of the temperature gradient, and realizes crystal growth at the seed crystal 300 on the crucible cover 202. At the same time, the temperature of the doping mechanism 100 in the growth crucible 200 also gradually increases, and continues to transfer heat to the silicon nitride powder 400 inside it, and the temperature of the silicon nitride powder 400 will also gradually increase, and decompose into elemental nitrogen and silicon, such as silicon and nitrogen gas, by heat. In the early stage of crystal growth, the doping mechanism 100 is controlled to be gradually opened at a speed V1 from a sealed state (i.e., the first state), and the nitrogen gas decomposed by the heat of the silicon nitride powder 400 continues to move upward through the open mouth. On the one hand, the nitrogen gas will be doped into the growing silicon carbide crystal to achieve the doping of nitrogen elements in the silicon carbide crystal to obtain a guided silicon carbide crystal; on the other hand, the airflow formed by the nitrogen gas can promote the sublimation of the silicon carbide powder 500 above, and can also drive the sublimated silicon carbide vapor to move toward the seed crystal 300, thereby accelerating the growth rate of the crystal. It should be noted that the concentration of nitrogen elements decomposed in the doping mechanism 100 in the early stage is high, and controlling the size of the open mouth can control the sublimation speed of nitrogen elements and silicon elements, thereby controlling the doping concentration of nitrogen elements in the growth of silicon carbide crystals to control the resistivity of silicon carbide wafers.

[0065] As the reaction proceeds, in the middle and late stages of crystal growth, the doping mechanism 100 is controlled to continue to open at another speed V2 until it reaches the second state. Since the concentration of nitrogen decomposed in the doping mechanism 100 in the late stage is low, the opening speed V2 at this time is greater than V1 compared to the early stage of crystal growth, and the opening is also larger, which accelerates the sublimation speed of nitrogen and silicon elements, so that the concentration of nitrogen in the growth crucible 200 remains unchanged, thereby controlling the resistivity of the silicon carbide crystal to remain unchanged in the late stage of crystal growth. At the same time, the concentration of silicon decomposed in the silicon carbide powder 500 in the growth crucible 200 in the late stage of crystal growth decreases, and the concentration of carbon increases, and it is in a carbon-rich state, so the opening is rapidly enlarged at a faster speed, which can accelerate the rapid diffusion of silicon elements in the doping mechanism 100 into the growth crucible 200 to supplement the concentration of silicon elements in the growth crucible 200. On the one hand, the supplemented silicon elements can generate silicon carbide with carbon elements for growth; on the other hand, it can reduce the entry of C clusters into the crystal, thereby reducing the generation of defects such as C encapsulation and micropipes.

[0066] According to the silicon carbide crystal growth device of the present invention, a doping mechanism 100 is provided in the growth crucible 200, and the state of the doping mechanism 100 is adjustable. The silicon nitride powder 500 inside can be decomposed by heat during the crystal growth process. By adjusting the doping mechanism 100, the nitrogen and silicon elements in the growth crucible 200 can be supplemented at different stages of the crystal growth. In the early stage of crystal growth, nitrogen elements will be doped into the growing silicon carbide crystal to achieve the doping of nitrogen elements in the silicon carbide crystal. The doping of nitrogen elements can effectively reduce the resistivity of silicon carbide to obtain guided silicon carbide crystals; at the same time, the airflow formed by nitrogen elements can promote the sublimation of the silicon carbide powder 500 above, and can also drive the sublimated silicon carbide vapor to move in the direction of the seed crystal 300, thereby accelerating the growth rate of the crystal. In the middle and late stages of crystal growth, the concentration of nitrogen decomposed in the doping mechanism 100 is low, so the doping mechanism 100 is controlled to continue to open to the second state at a faster speed, accelerating the sublimation speed of nitrogen and silicon elements in the doping mechanism 100, so that the concentration of nitrogen in the growth crucible 200 remains unchanged, so as to control the resistivity of the silicon carbide crystal to remain unchanged in the late stage of crystal growth. At the same time, the opening is rapidly enlarged at a faster speed, which can accelerate the sublimation of silicon elements in the doping mechanism 100 into the growth crucible 200 to supplement the concentration of silicon elements in the growth crucible 200. On the one hand, the supplemented silicon elements can generate silicon carbide with carbon elements for growth; on the other hand, it can reduce the entry of C clusters into the crystal, thereby reducing the generation of defects such as C encapsulation and micropipes. In addition, the doping mechanism 100 can also be used as a heat source to further heat the silicon carbide powder 500, so that the silicon carbide powder 500 is heated more evenly and sublimated more evenly, thereby improving the utilization rate of the silicon carbide powder 500.

[0067] In some embodiments of the present invention, reference Figures 1 to 7As shown, the doping mechanism 100 may include a doping unit 10, a support rod 20 and a power mechanism 30, wherein the support rod 20 can be rotatably installed in the crucible body 201; the power mechanism 30 is placed outside the crucible body 201, and the power mechanism 30 is connected to the support rod 20; there are multiple doping units 10, and the multiple doping units 10 are spaced apart and mounted on the support rod 20; wherein the silicon nitride powder 400 is loaded in the doping unit 10, and in the first state, the doping unit 10 is in a sealed state; in the second state, the doping unit 10 is in an at least partially open state; under the action of the power mechanism 30 and the support rod 20, the doping unit 10 switches back and forth between the first state and the second state.

[0068] For example, a plurality of doping units 10 are mounted on the support rod 20 at equal intervals from bottom to top along the axial direction of the support rod 20, and the support rod 20 can be rotatably mounted on the bottom wall of the growth crucible 200. Specifically, the lower end of the support rod 20 passes through the bottom wall of the growth crucible 200 and extends to the outside thereof, and the power mechanism 30 is connected to the bottom end of the support rod 20. Under the action of the power mechanism 30, the support rod 20 rotates, and the part of the doping unit 10 above it rotates together with the support rod 20, so that the doping unit 10 switches back and forth between the first state and the second state. By controlling the rotation speed of the support rod 20, the switching speed of the doping unit 10 between the two states can be controlled to adapt to different crystal growth periods.

[0069] It is understandable that the number of doping units 10 can be increased or decreased as needed, and the amount of silicon nitride powder 400 loaded in the doping unit 10 can also be increased or decreased as needed to meet the needs of growing different amounts of silicon carbide powder, thereby achieving the supplement of nitrogen and silicon elements when growing crystals of different sizes or thicknesses. The entire structure is adjustable and has a wide range of adaptability. Among them, the number of doping units 10 is preferably 1, 2 or 3.

[0070] In some embodiments of the present invention, reference Figures 1 to 7As shown, the doping unit 10 may include a storage box 11 and a sealing assembly 12, the storage box 11 is formed with a hollow cavity 110, an upper opening 102 and a lower opening 101 connected to the hollow cavity 110 are provided at the center of the storage box 11, and a top wall of the storage box 11 is provided with a plurality of upper through holes 103 connected to the hollow cavity 110; the sealing assembly 12 is arranged in the hollow cavity 110, and in a first state, the sealing assembly 12 completely covers all the upper through holes 103, so that the entire doping unit 10 is in a sealed state; in a second state, the sealing assembly 12 does not completely cover or at least partially covers the upper through holes 103, so that the upper through holes 103 are at least partially exposed, ensuring that the entire doping unit 10 is in an at least partially open state. Among them, the storage box 11 is mounted on the support rod 20, and the sealing assembly 12 is inserted into the support rod 20. When the support rod 20 rotates, the sealing assembly 12 rotates synchronously with the support rod 20, and the storage box 11 does not move or has a different rotation speed from the support rod 20.

[0071] For example, the storage box 11 may be a hollow cylindrical structure, the diameter of the storage box 11 is smaller than the inner diameter of the accommodating cavity 203, the sealing assembly 12 is installed in the storage box 11, and the upper through hole 103 is completely blocked or at least partially unblocked by adjusting the relative position of the sealing assembly 12 and the storage box 11 in the circumferential direction, so as to realize the switching of the entire doping unit 10 between the first state and the second state. The diameter of the upper through hole may be 5-30 mm.

[0072] It is understandable that, when in use, the amount of silicon nitride powder 400 to be loaded can be determined according to the amount of silicon carbide powder 500 in the crucible body 201. When loading, the upper through hole 103 can be at least partially exposed by adjusting the position of the sealing component 12, so that the silicon nitride powder 400 can be loaded into the storage box 11. Then, the position of the sealing component 12 is adjusted again so that the upper through hole 103 is completely blocked, and the entire doping unit 10 is in the first state. The loading of silicon carbide powder 500 in the crucible body 201 can be carried out in conjunction with the loading of silicon nitride powder 400. For example, the silicon carbide powder 500 can cover the entire doping mechanism 100.

[0073] During crystal growth, under the action of the induction coil 600, heat is transferred to the doping mechanism 100 inside the growth crucible 200. On the one hand, the temperature of the silicon carbide powder 500 gradually increases and sublimates. The sublimated silicon carbide vapor moves toward the crucible cover 202 under the action of the axial temperature gradient, and realizes crystal growth at the seed crystal 300 on the crucible cover 202; on the other hand, the temperature of the silicon nitride powder 400 in the doping mechanism 100 will also gradually increase, and decompose into elemental nitrogen and silicon under heat. At the beginning of crystal growth, the power mechanism 30 is started, and the sealing assembly 12 rotates synchronously with the support rod 20. Since the storage box 11 does not move or has a different rotation speed from the support rod 20, the sealing assembly 12 can be switched from completely covering the upper through hole 103 to gradually exposing the upper through hole 103, so that the elements decomposed by heat can continue to move upward through the open mouth, and then be doped into the growing silicon carbide crystal, so as to realize the doping of nitrogen elements in the silicon carbide crystal, thereby obtaining a guided silicon carbide crystal. In the middle and late stages of crystal growth, the sealing assembly 12 is controlled to continue to open until it reaches the second state. Since the concentration of nitrogen decomposed in the late doping mechanism 100 is low, the opening speed is faster and the opening is larger than that in the early stages of crystal growth, which accelerates the sublimation and diffusion speeds of nitrogen and silicon elements to maintain the concentration of nitrogen in the growth crucible 200 unchanged, thereby controlling the resistivity of the silicon carbide crystal to remain unchanged in the late stages of crystal growth, and ensuring the supplementation of silicon elements in the late stages.

[0074] In some embodiments of the present invention, reference Figures 1 to 7 As shown, all the upper through holes 103 are arranged in multiple rows and columns in a tic-tac-toe pattern along the upper surface of the storage box 11, and the distance between any two adjacent upper through holes 103 in each row is the same, and the distance between any two adjacent upper through holes 103 in each column is the same.

[0075] It can be understood that all the upper through holes 103 are evenly distributed on the storage box 11 in this way, which is more conducive to the uniform diffusion of the sublimated elements inside it to the outside. While participating in the reaction, it can also provide a uniform upward thrust to push the sublimated silicon carbide gas to move upward.

[0076] Of course, all the upper through holes 103 can also be divided into multiple groups from the inside to the outside along the radial direction of the storage box 11, and the connecting line of each group of upper through holes 103 can be circular, and all the upper through holes 103 in each group are evenly arranged along the circumferential direction of the storage box 11. For example, the number of upper through holes 103 in each group gradually increases from the inside to the outside, and the distance between any two adjacent upper through holes 103 in each group is equal. By controlling the sealing component 12, all the upper through holes 103 can be opened synchronously or evenly, so that the diffusion of the sublimation gas is more uniform and the doping effect is better.

[0077] In some embodiments of the present invention, the sealing assembly 12 may include a first baffle 121, which is mounted on the support rod 20 and arranged close to the top wall of the storage box 11; in a first state, the first baffle 121 completely blocks all the upper through holes 103; in a second state, the first baffle 121 is at least partially separated from the upper through holes 103. For example, a through hole matching the upper through hole 103 may be provided on the first baffle 121, and by rotating the first baffle 121, the upper through hole 103 may be completely blocked (that is, all the through holes are not connected to the upper through hole 103), and at the same time, the through hole may be at least partially connected to the upper through hole 103, which is conducive to the diffusion of the internal sublimation elements.

[0078] In some embodiments of the present invention, reference Figures 1 to 7 As shown, the bottom wall of the storage box 11 is provided with a plurality of lower through holes 104 connected to the hollow cavity 110, and the sealing assembly 12 also includes a second baffle 122, which is mounted on the support rod 20 and arranged close to the bottom wall of the storage box 11; similar to the lower through holes 104 and the second baffle 122, the second baffle 122 can completely block all the lower through holes 104, and can also be at least partially separated from the lower through holes 104. Its structure can refer to the upper through hole 103 and the first baffle 121, so it will not be described here. It should be noted that when the silicon nitride powder 400 is loaded, the second baffle 122 always completely blocks all the lower through holes 104 to prevent the silicon nitride powder 400 from flowing out through the lower through holes 104.

[0079] It can be understood that during crystal growth, the entire doping mechanism 100 is in the first state, the first baffle 121 completely blocks the upper through hole 103, and the second baffle 122 completely blocks the lower through hole 104. In the early stage of crystal growth, the first baffle 121 and the second baffle 122 rotate together with the support rod 20, but only the upper through hole 103 is gradually exposed, and the lower through hole 104 is always in a completely blocked state, and the sublimated elements can only flow out through the upper through hole 103. In the middle and late stages of crystal growth, the first baffle 121 rotates with the second baffle 122, the exposed area of ​​the upper through hole 103 (i.e., the area where the upper through hole 103 is connected to the hollow cavity 110) gradually increases, and the lower through hole 104 is gradually exposed, and the exposed area gradually increases. Until the upper through hole 103 is completely exposed, the power mechanism 30 stops working and the support rod 20 stops rotating. When the lower through hole 104 is exposed, part of the silicon nitride powder 400 in the storage box 11 that has not yet sublimated will fall into the growth crucible 200. On the one hand, the silicon nitride powder 400 that falls in will continue to sublimate into silicon and nitrogen elements faster, thereby realizing the replenishment of silicon and nitrogen elements; on the other hand, the sublimated silicon carbide gas can also continue to move toward the seed crystal through the lower through hole 104, the hollow cavity 110, and the upper through hole 103 in sequence, participate in the growth of the crystal, increase the movement path of the silicon carbide gas, make the atmosphere composition in all directions uniform, and help improve the quality of the crystal. Among them, the stopping of the power mechanism 30 can be carried out by using the existing conventional limit column, such as calculating the rotation angle in advance and stopping the rotation after reaching the angle. It does not belong to the protection focus of the present invention, so it will not be repeated here.

[0080] In some embodiments of the present invention, reference Figures 1 to 7 As shown, the storage box 11 may include a box body 111 and a box cover 112; the box body 111 defines a storage cavity 113 with an open top; the box cover 112 is detachably mounted on the top of the box body 111; wherein the upper opening 102 is opened at the center of the box cover 112, the lower opening 101 is opened at the center of the box body 111, and the upper through hole 103 is opened on the box cover 112 and is located around the upper opening. Specifically, the box body 111 can be rotatably mounted on the support rod 20. During installation, the box body 111 is first mounted on the support rod 20, then the silicon nitride powder 400 is added, and then the first baffle 121 is clamped on the support rod 20, and finally the box cover 112 is placed above the first baffle 121 and connected and fixed to the box body 111. In order to ensure that the first baffle 121 and the support rod 20 can rotate smoothly and synchronously, a gap is left between the first baffle 121 and the upper surface of the silicon nitride powder 400 to reduce friction when it rotates.

[0081] In view of this, when the lower through hole 104 and the second baffle 122 are provided on the box body 111, the lower through hole 104 is opened on the box body 111 around the lower opening, and the second baffle 122 is clamped on the support rod 20 near the bottom wall of the box body 111. During installation, after the box body 111 is installed, the second baffle 122 is first clamped in the support rod 20, and the second baffle 122 completely blocks the lower through hole 104, and after the second baffle 122 rotates, the lower through hole 104 is first blocked for a period of time and then gradually exposed. Then, the silicon nitride powder 400, the first baffle 121 and the box cover 112 are sequentially loaded. It should be noted that during installation, the first baffle 121 completely blocks the upper through hole 103, and once the first baffle 121 rotates, the upper through hole 103 will gradually be exposed.

[0082] According to an embodiment of the present invention, a method for preparing silicon carbide crystals using the above-mentioned growth device includes the following steps: in the early stage of crystal growth, controlling the doping mechanism 100 to gradually switch from the first state to the third state at a first speed; in the middle and late stages of crystal growth, controlling the doping mechanism 100 to switch from the third state to the second state at a second speed; wherein the third state is between the first state and the second state, and the first speed is less than the second speed.

[0083] It is understandable that when the growth device is used for the first time, pretreatment is performed first. After the pretreatment is completed, loading can be performed. The installation of the doping mechanism 100 can refer to the above description. The loading of the entire doping mechanism 100 can be carried out in conjunction with the loading of the silicon carbide powder 500. After the loading is completed, the entire growth crucible 200 can be placed in a hot field for crystal growth. In the first stage, the vacuum pressure is reduced to 10 -5 ~10 -6 mbar; second stage: leak detection for 1 to 2 hours; third stage: mechanical pump continuously evacuates, heats up to 1200 to 1600 ° C, and maintains the temperature for 2 hours; fourth stage: open the inert gas flow rate of 10 to 300 sccm, maintain the pressure value in the furnace at 1 to 10 mbar, and heats up to 2000 to 2400 ° C at the same time, maintains for 20 to 50 hours, and controls the doping mechanism 100 to rotate at a first speed, so that it gradually switches from the first state to the third state between the first state and the second state; fifth stage: control the doping mechanism 100 to rotate at a second speed greater than the first speed, so that it switches from the third state to the second state, and maintains for 40 to 60 hours of crystal growth; sixth stage: gradually cool down, gradually cool down to 300 to 500 ° C for 10 to 15 hours, and then increase the inert gas flow rate of 100 to 500 sccm, and naturally cool down to room temperature. Finally, detection: take out the grown crystal, cut, grind and polish, and finally perform conductivity detection. The inert gas can be either argon or helium.

[0084] In view of this, at the initial stage of crystal growth, the doping mechanism 100 is controlled to gradually open from a sealed state (i.e., the first state) at a speed of V1, and the nitrogen gas decomposed by the heat of the silicon nitride powder 400 continues to move upward through the open port. On the one hand, the nitrogen gas will be doped into the growing silicon carbide crystal to achieve the doping of nitrogen elements in the silicon carbide crystal to obtain a guided silicon carbide crystal; on the other hand, the airflow formed by the nitrogen gas can promote the sublimation of the silicon carbide powder 500 above, and can also drive the sublimated silicon carbide vapor to move toward the seed crystal 300, thereby accelerating the growth rate of the crystal. It should be noted that the concentration of nitrogen elements decomposed in the doping mechanism 100 in the early stage is high, and controlling the size of the open port can control the sublimation speed of nitrogen elements and silicon elements, thereby controlling the doping concentration of nitrogen elements in the growth of silicon carbide crystals to control the resistivity of silicon carbide wafers.

[0085] In the middle and late stages of crystal growth, the doping mechanism 100 is controlled to continue to open at another speed V2 until it reaches the second state. Since the concentration of nitrogen decomposed in the doping mechanism 100 in the late stage is low, the opening speed V2 at this time is greater than V1 compared to the early stage of crystal growth, and the opening is also larger, which accelerates the sublimation speed of nitrogen and silicon elements, so that the concentration of nitrogen in the growth crucible 200 remains unchanged, thereby controlling the resistivity of the silicon carbide crystal to remain unchanged in the late stage of crystal growth. At the same time, the concentration of silicon decomposed by the silicon carbide powder 500 in the growth crucible 200 in the late stage of crystal growth decreases, and the concentration of carbon increases, and it is in a carbon-rich state. Therefore, the opening is rapidly enlarged at a faster speed, which can accelerate the rapid diffusion of silicon elements in the doping mechanism 100 into the growth crucible 200 to supplement the concentration of silicon elements in the growth crucible 200. On the one hand, the supplemented silicon elements can generate silicon carbide with carbon elements for growth; on the other hand, it can reduce the entry of C clusters into the crystal, thereby reducing the generation of defects such as C encapsulation and micropipes.

[0086] According to the method for preparing silicon carbide crystals using a growth device in an embodiment of the present invention, at the initial stage of crystal growth, the doping mechanism 100 is controlled to gradually switch from a first state to a third state between the first state and the second state at a first speed, so that the sublimated nitrogen element can be doped into the growing silicon carbide crystal, effectively reducing the resistivity of silicon carbide to obtain a guided silicon carbide crystal; at the same time, the airflow formed by the sublimated elements can promote the sublimation of the silicon carbide powder 500 above, and can also drive the sublimated silicon carbide vapor to move in the direction of the seed crystal 300, thereby accelerating the growth rate of the crystal. In the middle and late stages of crystal growth, the doping mechanism 100 is controlled to switch from the third state to the second state at a second speed greater than the first speed, and continues to open at a faster speed, which accelerates the sublimation speed of nitrogen and silicon elements in the doping mechanism 100, so that the concentration of nitrogen elements in the growth crucible 200 remains unchanged, so as to control the resistivity of the silicon carbide crystal to remain unchanged in the late stages of crystal growth; at the same time, the opening is rapidly enlarged at a faster speed, which can accelerate the sublimation of silicon elements in the doping mechanism 100 into the growth crucible 200 to supplement the concentration of silicon elements in the growth crucible 200. On the one hand, the supplemented silicon elements can generate silicon carbide with carbon elements for growth; on the other hand, it can reduce the entry of C clusters into the crystal, thereby reducing the generation of defects such as C encapsulation and microtubes, and improving the quality of the crystal. In addition, the doping mechanism 100 in the growth crucible 200 can also be used as a heat source to further heat the silicon carbide powder 500, so that the silicon carbide powder 500 is heated more evenly and sublimated more evenly, thereby improving the utilization rate of the silicon carbide powder 500.

[0087] In some embodiments of the present invention, the weight ratio of silicon nitride powder 400 to silicon carbide powder 500 in growth crucible 200 is 1:20 to 1:200. When the weight ratio of silicon nitride powder 400 to silicon carbide powder 500 is 1:20 to 1:200, the effect is best.

[0088] In some embodiments of the present invention, the particle size of the silicon carbide powder 500 is 20-40 meshes, and the particle size of the silicon nitride powder 400 is 1-3 meshes; the diameter of the upper through hole is 2-5 cm. When the silicon nitride powder 400 and the silicon carbide powder 500 are mixed in this mesh ratio, on the one hand, the silicon nitride powder 400 can be controlled to sublime later than the silicon carbide powder 500, so as to avoid increasing the early silicon enrichment and ensure the normal growth of the crystal.

[0089] The present application is further described below through specific embodiments.

[0090] Assuming that the total rotation angle of the doping mechanism is 2°, the first speed is 0.04-0.1° / h, and the second speed is 0.08-0.2° / h.

[0091] Embodiment 1:

[0092] The method for preparing silicon carbide crystal using the above-mentioned growth device in this embodiment is carried out according to the following steps:

[0093] Step S1, loading: Assemble the doping mechanism 100 in the growth crucible 200, with the lowest doping unit 10 of the doping mechanism 100 20 mm away from the bottom of the growth crucible 200, and place 30 g of silicon nitride powder 400 in the doping mechanism, put 2000 g of silicon carbide powder into the crucible, cover it with a graphite cover, and fix it with graphite bolts.

[0094] Step S2, synthesis: Phase 1: reduce the vacuum pressure to 10 -5 ~10 -6 mbar; second stage: leak detection for 2h; third stage: mechanical pump continuously evacuates, heats up to 1600℃, and maintains the temperature for 2h; fourth stage: open the inert gas flow rate of 200sccm, maintain the pressure value in the furnace at 10mbar, heats up to 2400℃, maintains for 30h, and rotates the support rod 20 to gradually open the upper through hole 103 of the doping mechanism 10 at a speed of 0.07° / h; fifth stage: continue to rotate the center rod of the device, gradually open the upper through hole 103 of the doping mechanism 10 at a speed of 0.2° / h, until the upper through hole 103 is fully opened, and then maintain for 60h crystal growth, sixth stage: gradually cool down, gradually cool down to 300~500℃ for 10~15h, and then increase the inert gas flow rate by 100~500sccm, and naturally cool down to room temperature.

[0095] Step S3, detection: Take out the grown crystal, cut, grind and polish it, and finally perform resistivity detection, such as Figure 8 shown.

[0096] Embodiment 2:

[0097] Step S1, loading: Assemble the doping mechanism 100 in the growth crucible 200, with the lowest doping unit 10 of the doping mechanism 100 20 mm away from the bottom of the growth crucible 200, and place 60 g of silicon nitride powder 400 in the doping mechanism, put 2000 g of silicon carbide powder into the crucible, cover it with a graphite cover, and fix it with graphite bolts.

[0098] Step S2, synthesis: Phase 1: reduce the vacuum pressure to 10 -5 ~10 -6mbar; second stage: leak detection for 2h; third stage: mechanical pump continuously evacuates, heats up to 1600℃, and maintains the temperature for 2h; fourth stage: open the inert gas flow rate of 200sccm, maintain the pressure value in the furnace at 10mbar, heats up to 2400℃, maintains for 30h, and rotates the support rod 20 to gradually open the upper through hole 103 of the doping mechanism 10 at a speed of 0.07° / h; fifth stage: continue to rotate the center rod of the device, gradually open the upper through hole 103 of the doping mechanism 10 at a speed of 0.2° / h, until the upper through hole 103 is fully opened, and then maintain for 60h crystal growth, sixth stage: gradually cool down, gradually cool down to 300~500℃ for 10~15h, and then increase the inert gas flow rate by 100~500sccm, and naturally cool down to room temperature.

[0099] Step S3, detection: Take out the grown crystal, cut, grind and polish it, and finally perform resistivity detection, such as Fig. 9 shown.

[0100] Embodiment 3:

[0101] Step S1, loading: Assemble the doping mechanism 100 in the growth crucible 200, with the lowest doping unit 10 of the doping mechanism 100 20 mm away from the bottom of the growth crucible 200, and place 80 g of silicon nitride powder 400 in the doping mechanism, put 2000 g of silicon carbide powder into the crucible, cover it with a graphite cover, and fix it with graphite bolts.

[0102] Step S2, synthesis: Phase 1: reduce the vacuum pressure to 10 -5 ~10 -6 mbar; second stage: leak detection for 2h; third stage: mechanical pump continuously evacuates, heats up to 1600℃, and maintains the temperature for 2h; fourth stage: open the inert gas flow rate of 200sccm, maintain the pressure value in the furnace at 10mbar, heats up to 2400℃, maintains for 30h, and rotates the support rod 20 to gradually open the upper through hole 103 of the doping mechanism 10 at a speed of 0.07° / h; fifth stage: continue to rotate the center rod of the device, gradually open the upper through hole 103 of the doping mechanism 10 at a speed of 0.2° / h, until the upper through hole 103 is fully opened, and then maintain for 60h crystal growth, sixth stage: gradually cool down, gradually cool down to 300~500℃ for 10~15h, and then increase the inert gas flow rate by 100~500sccm, and naturally cool down to room temperature.

[0103] Step S3, detection: Take out the grown crystal, cut, grind and polish it, and finally perform resistivity detection, such as Fig.10 shown.

[0104] Embodiment 4:

[0105] Step S1, loading: Assemble the doping mechanism 100 in the growth crucible 200, with the lowest doping unit 10 of the doping mechanism 100 40 mm away from the bottom of the growth crucible 200, and place 80 g of silicon nitride powder 400 in the doping mechanism, put 2000 g of silicon carbide powder into the crucible, cover it with a graphite cover, and fix it with graphite bolts.

[0106] Step S2, synthesis: Phase 1: reduce the vacuum pressure to 10 -5 ~10 -6 mbar; second stage: leak detection for 2h; third stage: mechanical pump continuously evacuates, heats up to 1600℃, and maintains the temperature for 2h; fourth stage: open the inert gas flow rate of 200sccm, maintain the pressure value in the furnace at 10mbar, heats up to 2400℃, maintains for 30h, and rotates the support rod 20 to gradually open the upper through hole 103 of the doping mechanism 10 at a speed of 0.07° / h; fifth stage: continue to rotate the center rod of the device, gradually open the upper through hole 103 of the doping mechanism 10 at a speed of 0.2° / h, until the upper through hole 103 is fully opened, and then maintain for 60h crystal growth, sixth stage: gradually cool down, gradually cool down to 300~500℃ for 10~15h, and then increase the inert gas flow rate by 100~500sccm, and naturally cool down to room temperature.

[0107] Step S3, detection: Take out the grown crystal, cut, grind and polish it, and finally perform resistivity detection, such as Fig.11 shown.

[0108] Embodiment 5:

[0109] Step S1, loading: Assemble the doping mechanism 100 in the growth crucible 200, with the lowest doping unit 10 of the doping mechanism 100 60 mm away from the bottom of the growth crucible 200, and place 80 g of silicon nitride powder 400 in the doping mechanism 100, put 2000 g of silicon carbide powder into the crucible, cover it with a graphite cover, and fix it with graphite bolts.

[0110] Step S2, synthesis: Phase 1: reduce the vacuum pressure to 10 -5 ~10 -6mbar; second stage: leak detection for 2h; third stage: mechanical pump continuously evacuates, heats up to 1600℃, and maintains the temperature for 2h; fourth stage: open the inert gas flow rate of 200sccm, maintain the pressure value in the furnace at 10mbar, heats up to 2400℃, maintains for 30h, and rotates the support rod 20 to gradually open the upper through hole 103 of the doping mechanism 10 at a speed of 0.07° / h; fifth stage: continue to rotate the center rod of the device, gradually open the upper through hole 103 of the doping mechanism 10 at a speed of 0.2° / h, until the upper through hole 103 is fully opened, and then maintain for 60h crystal growth, sixth stage: gradually cool down, gradually cool down to 300~500℃ for 10~15h, and then increase the inert gas flow rate by 100~500sccm, and naturally cool down to room temperature.

[0111] Step S3, detection: Take out the grown crystal, cut, grind and polish it, and finally perform resistivity detection, such as Fig.12 shown.

[0112] In Examples 1 to 5, the weight of the silicon carbide powder 500, the weight of the added silicon nitride powder 400, and the distance between the doping mechanism 100 and the bottom wall of the growth crucible 200 can be seen in the table below.

[0113] Serial number / weight Silicon carbide powder Silicon nitride powder Distance from crucible bottom (mm) Example 1(g) 2000 30 20 Example 2(g) 2000 60 20 Example 3(g) 2000 80 20 Example 4(g) 2000 80 40 Example 5(g) 2000 80 60

[0114] In Examples 1 to 5, the resistivity range and carbon coating conditions of the wafers finally obtained are shown in the table below.

[0115] Serial number / weight Resistivity (Ω·cm) Carbon packaging % Example 1(g) 0.0235～0.0251 2.38 Example 2(g) 0.0212～0.0222 1.25 Example 3(g) 0.0187～0.0231 0.42 Example 4(g) 0.0161～0.0212 0.05 Example 5(g) 0.0155～0.0210 0.14

[0116] Comparative analysis shows that, based on Example 1, Examples 2 and 3 adjust the amount of silicon nitride powder 400 placed in the doping mechanism 100 in step S1, and other conditions remain unchanged. Based on Example 3, Examples 4 and 5 adjust the distance between the bottom doping unit 10 of the doping mechanism 100 and the bottom of the growth crucible 200 in step S1, and other conditions remain unchanged. Among Examples 1 to 5, Example 4 is the best.

[0117] Combination Figures 8 to 12 As can be seen from the table above, the resistivity and carbon encapsulation of the silicon carbide crystal prepared by the method of the present invention are well controlled. For the same silicon carbide powder 500, the more silicon nitride powder 400 is added, the lower the resistivity is, and the carbon encapsulation ratio is also significantly reduced; for the same silicon carbide powder 500 and silicon nitride powder 400, the change of the installation position of the doping mechanism 100 will also change the generated carbon encapsulation. If the doping mechanism 100 is installed too high or too low, the carbon encapsulation ratio will increase.

[0118] In summary, the present invention provides a doping mechanism 100 in the growth crucible 200, and the doping mechanism 100 is filled with silicon nitride powder 500, and the silicon nitride powder 400 is used to achieve the doping of nitrogen and the supplementation of silicon in the growth process of silicon carbide crystals. When charging, by adjusting the dopant at different positions of the powder (i.e., the installation position of the doping mechanism) and different concentrations (i.e., the weight of the silicon nitride powder), the supplementation of nitrogen and silicon in the growth crucible 200 can be achieved at different stages of crystal growth to grow qualified silicon carbide crystals. Specifically, in the early stage of crystal growth, nitrogen will be doped into the growing silicon carbide crystal to achieve the doping of nitrogen in the silicon carbide crystal. The doping of nitrogen can effectively reduce the resistivity of silicon carbide to obtain a guided silicon carbide crystal; at the same time, the airflow formed by nitrogen can promote the sublimation of the silicon carbide powder 500 above, and can also drive the sublimated silicon carbide vapor to move in the direction of the seed crystal 300, thereby accelerating the growth rate of the crystal. In the middle and late stages of crystal growth, the concentration of nitrogen decomposed in the doping mechanism 100 is low, so the doping mechanism 100 is controlled to continue to open to the second state at a faster speed, accelerating the sublimation speed of nitrogen and silicon elements in the doping mechanism 100, so that the concentration of nitrogen in the growth crucible 200 remains unchanged, so as to control the resistivity of the silicon carbide crystal to remain unchanged in the late stage of crystal growth. At the same time, the opening is rapidly enlarged at a faster speed, which can accelerate the sublimation of silicon elements in the doping mechanism 100 into the growth crucible 200 to supplement the concentration of silicon elements in the growth crucible 200. On the one hand, the supplemented silicon elements can generate silicon carbide with carbon elements for growth; on the other hand, it can reduce the entry of C clusters into the crystal, thereby reducing the generation of defects such as C encapsulation and microtubes, and improving the quality of the crystal. In addition, the doping mechanism 100 can also be used as a heat source to further heat the silicon carbide powder 500, so that the silicon carbide powder 500 is heated more evenly and sublimated more evenly, thereby improving the utilization rate of the silicon carbide powder 500.

[0119] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0120] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0121] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0122] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0123] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0124] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A silicon carbide crystal growth device, characterized in that: include: A growth crucible, the growth crucible comprising a crucible body and a crucible cover, the crucible body defining a receiving cavity with an open top, the crucible cover being mounted on the top of the crucible body, and a seed crystal being mounted on the bottom of the crucible cover; A doping mechanism, wherein the doping mechanism is disposed in the containing cavity, the doping mechanism is filled with silicon nitride powder, the doping mechanism has a first state and a second state, and can be switched between the first state and the second state; in the first state, the doping mechanism is in a sealed state; In the second state, the doping mechanism is in an at least partially open state.

2. A silicon carbide crystal growth device according to claim 1, characterized in that: The doping mechanism comprises: A support rod, the support rod being rotatably mounted in the crucible body; A power mechanism, the power mechanism is disposed outside the crucible body and connected to the support rod; A doping unit, wherein there are a plurality of the doping units, and the plurality of the doping units are spaced apart and sleeved on the support rod; Wherein, the silicon nitride powder is loaded in the doping unit, in the first state, the doping unit is in a sealed state; in the second state, the doping unit is in an at least partially open state; under the action of the power mechanism and the support rod, the doping unit switches between the first state and the second state.

3. The silicon carbide crystal growth device according to claim 2, characterized in that: The doping unit comprises: A storage box, wherein the storage box is formed with a hollow cavity, an upper opening and a lower opening communicating with the hollow cavity are provided at the center of the storage box, and a top wall of the storage box is provided with a plurality of upper through holes communicating with the hollow cavity; A sealing assembly, wherein the sealing assembly is disposed in the hollow cavity so that the upper through hole is completely blocked or at least partially exposed; Wherein, the storage box is mounted on the support rod, and the sealing assembly is inserted on the support rod. When the support rod rotates, the sealing assembly rotates synchronously with the support rod, and the storage box remains stationary or has a different rotation speed from that of the support rod.

4. The silicon carbide crystal growth device according to claim 3, characterized in that: All the upper through holes are arranged in multiple rows and columns in a tic-tac-toe pattern along the upper surface of the storage box, and the distance between any two adjacent upper through holes in each row is the same, and the distance between any two adjacent upper through holes in each column is the same.

5. The silicon carbide crystal growth device according to claim 3, characterized in that: The sealing assembly includes a first baffle, which is clamped on the support rod and arranged close to the top wall of the storage box; In the first state, the first baffle completely blocks all of the upper through holes; in the second state, the first baffle is at least partially separated from the upper through holes.

6. The silicon carbide crystal growth device according to claim 5, characterized in that: The bottom wall of the storage box is provided with a plurality of lower through holes communicating with the hollow cavity; the sealing assembly further comprises a second baffle plate, which is clamped on the support rod and arranged close to the bottom wall of the storage box; In the first state, the second baffle completely blocks all of the lower through holes; in the second state, the second baffle is at least partially separated from the lower through holes.

7. The silicon carbide crystal growth device according to claim 3, characterized in that: The storage box comprises: A box body, wherein the box body defines a storage cavity with an open top; A box cover, the box cover is detachably mounted on the top of the box body; The upper opening is opened at the center of the box cover, the lower opening is opened at the center of the box body, and the upper through holes are opened on the box cover around the upper opening.

8. A method for growing silicon carbide crystals using the silicon carbide crystal growth apparatus according to claim 1, characterized in that: include: At the beginning of crystal growth, controlling the doping mechanism to gradually switch from the first state to the third state at a first speed; In the middle and late stages of crystal growth, controlling the doping mechanism to switch from the third state to the second state at a second speed; The third state is between the first state and the second state, and the first speed is lower than the second speed.

9. A method for growing silicon carbide crystal according to claim 8, characterized in that: The weight ratio of the silicon nitride powder to the silicon carbide powder in the growth crucible is 1:20 to 1:

200.

10. The method for growing silicon carbide crystal according to claim 9, characterized in that: The particle size of the silicon carbide powder is 20-40 meshes, and the particle size of the silicon nitride powder is 1-3 meshes.

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