Doping mechanism for silicon carbide crystal and silicon carbide crystal growing device with same
By using a doping mechanism to regulate the decomposition of silicon nitride powder during silicon carbide crystal growth, the problems of N2 concentration affecting resistivity and carbon element introduction defects were solved, thus achieving the growth of high-quality conductive silicon carbide crystals.
Patent Information
- Application Number
- CN202422760408.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-12
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2034-11-12
AI Technical Summary
In existing methods for preparing conductive silicon carbide crystals, the N2 concentration affects the resistivity and the introduction of carbon elements leads to defects, resulting in poor crystal quality.
By employing a doping mechanism, nitrogen and silicon elements are provided through the decomposition of silicon nitride powder within the doping unit. The state of the doping unit is adjusted to control the replenishment of nitrogen and silicon elements, thereby reducing resistivity and minimizing defects.
This study achieved improved resistivity stability and quality of conductive silicon carbide crystals, while reducing defects such as C-encapsulation and microtubes.
Smart Images
Figure CN223866827U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of silicon carbide crystals, and in particular to a doping mechanism for silicon carbide crystals and a silicon carbide crystal growth apparatus having the same. Background Technology
[0002] Based on their 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, after epitaxial growth, are used to manufacture discrete devices such as power devices and radio frequency devices. Conductive silicon carbide substrates are mainly used in high-power, high-voltage applications such as new energy vehicles, high-speed rail transportation, and power grid inverters. Existing methods for preparing conductive silicon carbide substrates mainly include physical vapor transport (PVT), chemical vapor transport (CVT), and high-temperature solution methods.
[0003] Currently, physical vapor transport (PVT) is one of the most commonly used methods. Its principle is as follows: silicon carbide powder in a crucible is heated to a temperature above 2100℃. The silicon carbide powder sublimates and deposits on a silicon carbide seed crystal on the crucible lid, growing simultaneously. N₂ is introduced to dope nitrogen, thus successfully growing silicon carbide with a resistivity of 0.015–0.025 Ω / cm. 2 The conductive silicon carbide crystal. However, in practical operation, this method has the following drawbacks:
[0004] First, the concentration of N2 in the crucible directly affects the resistivity of the silicon carbide crystals obtained.
[0005] Second, when N2 flows, it carries some carbon elements into the crystal, causing defects such as microtubules and spiral dislocations. Summary of the Invention
[0006] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a doping mechanism for silicon carbide crystals, capable of doping with nitrogen and silicon elements during crystal growth. Nitrogen effectively reduces the resistivity of silicon carbide, while silicon reacts with carbon to form silicon carbide, reducing carbon inclusions and improving the quality of the silicon carbide crystal.
[0007] The doping mechanism for silicon carbide crystals according to this utility model includes:
[0008] Mounting rod;
[0009] Doping unit, wherein the doping unit contains silicon nitride powder, and there are multiple doping units, which are spaced apart and mounted on the mounting rod;
[0010] A power mechanism, which is connected to the mounting rod;
[0011] The doping unit has a first state and a second state. In the first state, the doping unit is in a sealed state. In the second state, the doping unit is in a state that is at least partially open. Under the action of the power mechanism and the mounting rod, the doping unit switches between the first state and the second state.
[0012] According to the doping mechanism for silicon carbide crystals of this invention, the state of the doping unit is adjustable, and the internal silicon nitride powder can be thermally decomposed. By adjusting the doping unit, nitrogen and silicon elements can be replenished in the growth crucible at different stages of crystal growth. In the early stage of crystal growth, nitrogen is doped into the growing silicon carbide crystal, achieving nitrogen doping within the silicon carbide crystal. Nitrogen doping can effectively reduce the resistivity of silicon carbide to obtain a directional silicon carbide crystal. In the middle and later stages of crystal growth, the concentration of nitrogen decomposed in the later doping unit is low. Therefore, the doping unit is controlled to continue opening to the second state at a faster rate, accelerating the sublimation rate of nitrogen and silicon elements within the doping unit, so that the nitrogen concentration in the growth crucible remains constant, thereby controlling the resistivity of the silicon carbide crystal to remain constant in the later stage of crystal growth. Simultaneously, rapidly increasing the opening size accelerates the sublimation of silicon within the doped unit into the growth crucible, replenishing the silicon concentration in the crucible. This replenished silicon can react with carbon to form silicon carbide for growth; additionally, it reduces the intrusion of C clusters into the crystal, thereby minimizing defects such as C inclusions and microtubules, ultimately improving crystal quality. The entire doping mechanism is simple in structure and highly operable.
[0013] In some embodiments of this utility model, the doped unit has a petal-shaped structure, and the doped unit includes:
[0014] A storage box, the storage box having a petal-shaped structure, the storage box forming a petal-shaped hollow cavity, the storage box having an upper opening and a lower opening communicating with the hollow cavity at the center, and the storage box having several upper through holes communicating with the hollow cavity on the top wall;
[0015] A first sealing assembly is disposed within the hollow cavity to completely block or at least partially expose the upper through hole;
[0016] The storage box is fitted onto the mounting rod, and the first sealing assembly is inserted into the mounting rod. When the mounting rod rotates, the first sealing assembly rotates synchronously with the mounting rod, and the storage box remains stationary or rotates at a different speed than the mounting rod.
[0017] In some embodiments of this utility model, all the upper through holes are divided into multiple groups from the inside to the outside along the radial direction of the storage box, and the line connecting all the upper through holes in each group is circular, and the number and position of the upper through holes on each petal in the storage box are the same.
[0018] In some embodiments of this utility model, the storage box includes:
[0019] The box body has a petal-shaped box structure and defines a storage cavity with an open top;
[0020] The lid is a petal-shaped plate that fits into the box body, and the lid is detachably installed on the top of the box body;
[0021] The upper opening is located at the center of the lid, the lower opening is located at the center of the box body, and the upper through hole is located on each petal of the lid.
[0022] In some embodiments of this utility model, the first sealing component includes:
[0023] A first mounting ring is fitted onto the mounting rod;
[0024] The first baffle, there are multiple first baffles, all of which are evenly distributed along the circumferential direction of the first mounting ring, and the inner end of the first baffle is connected to the first mounting ring.
[0025] In this configuration, all the first baffles are arranged one-to-one within each petal of the storage box and are positioned close to the top wall of the storage box; in the first state, all the first baffles completely block all the upper through holes; in the second state, all the first baffles are at least partially separated from the upper through holes.
[0026] In some embodiments of this utility model, the side wall of the storage box is provided with a positioning groove, and the first sealing assembly is provided with a positioning block that cooperates with the positioning groove.
[0027] In some embodiments of this utility model, the projections of any two adjacent doped units on the mounting rod in the horizontal direction are arranged crosswise.
[0028] This invention also proposes a silicon carbide crystal growth device that can achieve nitrogen doping during crystal growth and reduce carbon encapsulation, ultimately obtaining crystals of better quality.
[0029] The silicon carbide crystal growth apparatus according to this utility model includes:
[0030] A growth crucible, comprising a crucible body and a crucible lid, the crucible body defining a top-open receiving cavity, the crucible lid being mounted on top of the crucible body, and a seed crystal being disposed at the bottom of the crucible lid;
[0031] The doping mechanism is the same as the doping mechanism for silicon carbide crystals described above, and the doping mechanism is rotatably mounted in the receiving cavity.
[0032] In some embodiments of this utility model, the particle size of the silicon carbide powder in the growth crucible is 20-40 mesh, and the particle size of the silicon nitride powder is 1-3 mesh.
[0033] Based on the aforementioned silicon carbide crystal growth apparatus, 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 and second states at a first speed. This allows sublimated nitrogen elements to be doped into the growing silicon carbide crystal, effectively reducing the resistivity of silicon carbide to obtain a directional silicon carbide crystal. At the same time, the gas flow formed by the sublimated elements can promote the sublimation of the silicon carbide powder above and also drive the sublimated silicon carbide vapor to move towards the seed crystal, thus accelerating the crystal growth rate. In the later 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. This allows the mechanism to continue opening at a faster rate, accelerating the sublimation of nitrogen and silicon elements within the doping mechanism. This ensures that the nitrogen concentration in the growth crucible remains constant, thus maintaining the resistivity of the silicon carbide crystal during the later stages of crystal growth. Simultaneously, the rapid increase in the opening speed accelerates the sublimation of silicon elements from the doping mechanism into the growth crucible, replenishing the silicon concentration there. This replenished silicon can, on the one hand, react with carbon to form silicon carbide for growth; on the other hand, it reduces the intrusion of C clusters into the crystal, thereby reducing defects such as C inclusions and microtubules, and improving crystal quality.
[0034] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0035] Figure 1 This is a schematic diagram of the structure of the doping mechanism for silicon carbide crystals according to this utility model;
[0036] Figure 2 yes Figure 1 Enlarged schematic diagram of the medium-doped unit;
[0037] Figure 3 This is a structural schematic diagram of the box body of this utility model;
[0038] Figure 4 This is a schematic diagram of the structure of the box cover of this utility model;
[0039] Figure 5 This is a structural schematic diagram of the first sealing component of this utility model;
[0040] Figure 6 This is a schematic diagram of the silicon carbide crystal growth apparatus of this utility model;
[0041] Figure 7 This is a schematic diagram of the doped unit in the first state (i.e., the completely sealed state);
[0042] Figure 8 yes Figure 7 A diagram illustrating the process of removing the lid;
[0043] Figure 9 This is the usage state of the silicon carbide crystal growth apparatus of this utility model;
[0044] Figure 10 This is a schematic diagram of the doped unit in the third state;
[0045] Figure 11 yes Figure 10 A diagram illustrating the process of removing the lid;
[0046] Figure 12 This is a schematic diagram of the doped unit in the second state (i.e., at least partially open);
[0047] Figure 13 yes Figure 12 A diagram illustrating the process of removing the lid;
[0048] Figure 14 This is a schematic diagram of the structure of the doping mechanism of this utility model in the second state;
[0049] Figure 15 yes Figure 14 A magnified schematic diagram of the doped unit.
[0050] Figure label:
[0051] Silicon carbide crystal growth apparatus 1000;
[0052] Doping mechanism 100;
[0053] Doping unit 10; lower opening 101; upper opening 102; upper through hole 103; storage box 11; hollow cavity 110; box body 111; box cover 112; storage cavity 113; first sealing assembly 12; first mounting ring 121; first baffle 122;
[0054] Mounting rod 20;
[0055] Power mechanism 30;
[0056] Silicon nitride powder 40;
[0057] Growth crucible 200; crucible body 201; crucible lid 202; receiving cavity 203;
[0058] Seed crystal 300;
[0059] Induction coil 400;
[0060] 500g silicon carbide powder. Detailed Implementation
[0061] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.
[0062] The following disclosure provides numerous different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.
[0063] The following is for reference. Figures 1-15 This invention describes a doping mechanism and growth apparatus for silicon carbide crystals according to embodiments of the present invention.
[0064] Reference Figures 1 to 15 As shown, according to an embodiment of the present invention, a silicon carbide crystal doping mechanism 100 includes a doping unit 10, a mounting rod 20, and a power mechanism 30. The doping unit 10 contains silicon nitride powder 40, and there are multiple doping units 10, which are spaced apart and mounted on the mounting rod 20. The output end of the power mechanism 30 is connected to the mounting rod 20 to drive the mounting rod 20 to rotate. The doping unit 10 has a first state and a second state. In the first state, the doping unit 10 is in a sealed state; in the second state, the doping unit 10 is in a state that is at least partially open. Under the action of the power mechanism 30 and the mounting rod 20, the doping unit 10 can switch between the first state and the second state.
[0065] For example, multiple doping units 10 are sequentially and equally spaced on the mounting rod 20 from bottom to top along its axial direction. Under the action of the power mechanism 30, the mounting rod 20 rotates, and a portion of the doping units 10 above it rotates together with the mounting rod 20, achieving the switching of the doping units 10 between a first state and a second state. By controlling the rotational speed of the mounting rod 20, the switching speed of the doping units 10 between the two states can be controlled to adapt to different crystal growth stages. The number of doping units 10 can be increased or decreased as needed, and the amount of silicon nitride powder 40 loaded into each doping unit 10 can also be increased or decreased as needed to meet the requirements of different quantities of silicon carbide powder for crystal growth. This allows for the replenishment of different amounts of nitrogen and silicon elements required for crystal growth of different sizes or thicknesses. The entire structure is adjustable and has a wide range of applications. Of course, two or three doping units 10 are optimal. The doping unit 10 and the mounting rod 20 can be made of graphite, thus giving them high-temperature resistance to adapt to the high-temperature environment of crystal growth. Simultaneously, they can continue to transfer heat internally, allowing the silicon nitride powder 40 to reach its decomposition temperature and decompose into elemental nitrogen and silicon, thus replenishing nitrogen and silicon elements. Alternatively, the doping mechanism 100 can be made of tantalum carbide or tungsten carbide.
[0066] Understandably, during use, the doping mechanism 100 can be placed inside the growth crucible 200. As the temperature of the growth crucible 200 rises, the temperature of the doping mechanism 100 gradually increases, and the heat continues to be transferred to the silicon nitride powder 40 inside. The temperature of the silicon nitride powder 40 will gradually rise and decompose into elemental nitrogen and silicon, such as silicon and nitrogen gas. By controlling the doping unit 10 to gradually open from a sealed state (i.e., the first state) and switch to the second state, the thermally decomposed nitrogen and silicon elements can continue to move upward through the open opening to be doped into the grown silicon carbide crystal, realizing the doping of nitrogen and the replenishment of silicon. On the one hand, throughout the crystal growth process, the doping of nitrogen can effectively reduce the resistivity of silicon carbide to obtain a directional silicon carbide crystal. On the other hand, since the growth crucible 200 is in a carbon-rich state in the later stage of crystal growth, the replenished silicon can react with carbon to form silicon carbide for crystal growth, while reducing the entry of C clusters into the crystal, thereby reducing the generation of defects such as C inclusions and microtubes, and improving the quality of the crystal.
[0067] It should be noted that the nitrogen concentration decomposed in the early doping unit 10 is high, while the nitrogen concentration decomposed in the later doping unit 10 is low. By controlling the opening speed and size of the opening of the doping unit 10, the sublimation rate of nitrogen and silicon can be controlled, thereby controlling the nitrogen doping concentration in the growth of silicon carbide crystal, so as to ensure that the resistivity of the entire crystal remains unchanged or within a preset range in the early and late stages.
[0068] According to the doping mechanism for silicon carbide crystals of this invention, the state of the doping unit 10 is adjustable, and the silicon nitride powder 40 inside can be thermally decomposed. By adjusting the doping unit 10, nitrogen and silicon elements can be replenished in the growth crucible 200 at different stages of crystal growth. In the early stage of crystal growth, nitrogen is doped into the growing silicon carbide crystal, achieving nitrogen doping within the silicon carbide crystal. Nitrogen doping can effectively reduce the resistivity of silicon carbide to obtain a directional silicon carbide crystal. In the middle and later stages of crystal growth, the concentration of nitrogen decomposed in the later doping unit 10 is low. Therefore, the doping unit 10 is controlled to continue opening to the second state at a faster rate, accelerating the sublimation rate of nitrogen and silicon elements in the doping unit 10, so that the concentration of nitrogen in the growth crucible 200 remains constant, thereby controlling the resistivity of the silicon carbide crystal to remain constant in the later stage of crystal growth. Simultaneously, rapidly increasing the opening size accelerates the sublimation of silicon within the doping unit 10 into the growth crucible 200, replenishing the silicon concentration in the crucible. This replenished silicon can react with carbon to form silicon carbide for growth; additionally, it reduces the intrusion of C clusters into the crystal, thereby minimizing defects such as C inclusions and microtubules, ultimately improving crystal quality. The entire doping mechanism 100 has a simple structure and is highly operable.
[0069] In some embodiments of this utility model, reference is made to Figures 1 to 15 As shown, the doping unit 10 has a petal-shaped structure. The doping unit 10 includes a storage box 11 and a first sealing assembly 12. The storage box 11 has a petal-shaped structure and forms a petal-shaped hollow cavity 110. The center of the storage box 11 is provided with an upper opening 102 and a lower opening 101 communicating with the hollow cavity 110. The top wall of the storage box 11 is provided with a plurality of upper through holes 103 communicating with the hollow cavity 110. The first sealing assembly 12 is disposed in the hollow cavity 110 so that the upper through holes 103 are completely blocked or at least partially exposed. The storage box 11 is fitted onto the mounting rod 20, and the first sealing assembly 12 is inserted into the mounting rod 20. When the mounting rod 20 rotates, the first sealing assembly 12 rotates synchronously with the mounting rod 20, and the storage box 11 remains stationary or rotates at a different speed than the mounting rod 20.
[0070] For example, the diameter of the storage box 11 is smaller than the inner diameter of the growth crucible 200. The first sealing assembly 12 is installed inside the storage box 11. By adjusting the relative position of the first sealing assembly 12 and the storage box 11 in the circumferential direction, the upper through hole 103 is completely blocked or at least partially exposed, thereby realizing the switching of the entire doping unit 10 between the first state and the second state. The diameter of the upper through hole can be 5-30 mm.
[0071] Understandably, during use, the amount of silicon nitride powder 40 can be determined based on the amount of silicon carbide powder 500 in the growth crucible 200. During loading, the position of the first sealing component 12 can be adjusted so that at least part of the upper through-hole 103 is exposed, allowing the silicon nitride powder 40 to be loaded into the storage box 11. Then, the position of the first 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 into the growth crucible 200 can be coordinated with the loading of silicon nitride powder 40; for example, the silicon carbide powder 500 can cover the entire doping mechanism 100.
[0072] During crystal growth, the temperature of the silicon carbide powder 500 in the growth crucible 200 gradually increases and sublimates. The sublimated silicon carbide vapor moves towards the seed crystal 300 under the action of the axial temperature gradient, and crystal growth is achieved at the seed crystal 300. At the same time, the temperature of the silicon nitride powder 40 in the doping mechanism 100 gradually increases and decomposes into elemental nitrogen and silicon. In the early stage of crystal growth, the power mechanism 30 is activated, and the first sealing component 12 rotates synchronously with the mounting rod 20. Since the storage box 11 is stationary or rotates at a different speed than the mounting rod 20, the first sealing component 12 can switch from completely covering the upper through hole 103 to gradually exposing the upper through hole 103, so that the thermally decomposed elements can continue to move upward through the open opening and be doped into the growing silicon carbide crystal, thereby achieving nitrogen doping in the silicon carbide crystal to obtain a directional silicon carbide crystal. In the middle and later stages of crystal growth, the first sealing component 12 is controlled to continue to be open until it reaches the second state. Since the nitrogen concentration decomposed in the later doping mechanism 100 is low, the opening speed is faster and the opening is larger than in the early stage of crystal growth. This accelerates the sublimation and diffusion rates of nitrogen and silicon elements, so as to maintain the nitrogen concentration in the growth crucible 200 at a constant level. This controls the resistivity of the silicon carbide crystal to remain constant in the later stage of crystal growth, while ensuring the replenishment of silicon elements in the later stage.
[0073] In some embodiments of this utility model, reference is made to Figures 1 to 15 As shown, all the upper through holes 103 are divided into multiple groups from the inside to the outside along the radial direction of the storage box 11. The line connecting all the upper through holes 103 in each group is circular, and the number and position of the upper through holes 103 on each petal of the storage box 11 are the same. For example, all the upper through holes 103 on any petal of the storage box 11 are arranged in a row along the radial direction of the storage box 11, and the distance between any two adjacent upper through holes 103 is equal. For example, the upper through holes 103 are elliptical holes, all the upper through holes 103 have the same minor axis, and the major axis of all the upper through holes 103 gradually increases from the inside to the outside. All the upper through holes 103 are arranged on the storage box 11 in this way, and all the upper through holes 103 can be opened simultaneously or uniformly, which is more conducive to the uniform diffusion of the sublimated elements inside, participating in the reaction, and also providing a uniform upward thrust to push the sublimated silicon carbide gas upward.
[0074] In some embodiments of this utility model, reference is made to Figures 1 to 15 As shown, the storage box 11 may include a box body 111 and a box lid 112. The box body 111 has a petal-shaped box structure and defines a storage cavity 113 with an open top. The box lid 112 is a petal-shaped plate that cooperates with the box body 111 and is detachably installed on the top of the box body 111. The upper opening 102 is opened at the center of the box lid 112, the lower opening 101 is opened at the center of the box body 111, the upper through hole 103 is opened on each petal in the box lid, and the first sealing assembly 12 is arranged inside the box body 111 and is snapped onto the mounting rod 20. Specifically, the housing 111 is rotatably mounted on the mounting rod 20. A mounting platform can be fitted onto the mounting rod 20, and the mounting platform has an arcuate groove containing ball bearings. The bottom of the housing 111 has an arcuate groove that mates with the ball bearings. The housing 111 is fitted onto the mounting rod 20 through the lower opening 101 and mounted on the mounting platform. When the mounting rod 20 rotates, the first sealing assembly 12 rotates with it. However, under the action of the ball bearings and the arcuate groove, the housing 111 does not rotate. Thus, by controlling the rotation of the mounting rod 20, the relative position of the first sealing assembly 12 and the housing 111 can be adjusted, thereby controlling the degree of obstruction of the upper through hole 103.
[0075] Understandably, during installation, the housing 111 is first mounted on the mounting rod 20, then silicon nitride powder 40 is added, followed by the first sealing assembly 12 being snapped onto the mounting rod 20, and finally the housing cover 112 is placed above the first sealing assembly 12 and connected and fixed to the housing 111. To ensure that the first sealing assembly 12 and the mounting rod 20 can rotate smoothly and synchronously, a gap is left between the first sealing assembly 12 and the upper surface of the silicon nitride powder 40 to reduce friction during rotation. In the first state, the first sealing assembly 12 completely covers all the upper through holes 103, so that the entire doped unit 10 is in a sealed state; in the second state, the relative position between the first sealing assembly 12 and the housing 111 changes, and the first sealing assembly 12 is at least partially exposed above the upper through holes 103, that is, all the upper through holes 103 are at least partially exposed, and the change in the relative position between the first sealing assembly 12 and the housing 111 can be controlled by the power mechanism 30. When the power mechanism 30 is activated, it begins to work, and the mounting rod 20 begins to rotate. The first sealing assembly 12 rotates along with the mounting rod 20 to achieve the switching of the entire doping unit 10 between the first and second states.
[0076] In some embodiments of this utility model, reference is made to Figures 1 to 15As shown, the first sealing assembly 12 may include a first mounting ring 121 and a first baffle 122. The first mounting ring 121 is snapped onto the mounting rod 20. There are multiple first baffles 122, all of which are evenly distributed along the circumferential direction of the first mounting ring 121, and the inner end of the first baffle 122 is connected to the first mounting ring 121. All the first baffles 122 are arranged one-to-one in each petal of the storage box 11 and are arranged close to the top wall of the storage box 11. In a first state, all the first baffles 122 completely block all the upper through holes 103. In a second state, all the first baffles 122 are at least partially separated from the upper through holes 103.
[0077] For example, each first baffle 122 may have a through hole that matches all the upper through holes 103 on the corresponding petals in the storage box 11. If the upper through holes 103 on each petal are identical, then the relative positions of all first baffles 122 and their corresponding upper through holes 103 are the same. By rotating the first baffle 122, the upper through holes 103 can be completely blocked (i.e., all through holes are not connected to the upper through holes 103), while at the same time, the through holes and the upper through holes 103 can be at least partially connected, which is conducive to the diffusion of sublimated elements inside.
[0078] Understandably, the first mounting ring 121 is snapped onto the mounting rod 20, and multiple first baffles 122 are evenly distributed along the circumference of the first mounting ring 121. Each first baffle 122 is inserted into each petal of the storage box 11. By controlling the rotation of the mounting rod 20, the relative position between the first baffle 122 and the petal can be adjusted, thereby adjusting the relative position between the through hole and the upper through hole 103 on the first baffle 122, thus controlling the degree of obstruction of the upper through hole 103, and thereby switching the entire doping unit 10 between the first state and the second state.
[0079] In some embodiments of this utility model, reference is made to Figures 1 to 15 As shown, the storage box 11 has a positioning groove on its side wall, and the first sealing assembly 12 has a positioning block that cooperates with the positioning groove. For example, the positioning groove can be an arc-shaped groove, and the positioning block can be an arc-shaped block. When the first sealing assembly 12 switches from the first state to the second state, the positioning block can just enter the positioning groove. At this time, if the mounting rod 20 continues to rotate, the first sealing assembly 12 will generate a pushing force on the storage box 11 through the positioning block, pushing the storage box 11 to rotate together.
[0080] Understandably, when the doped unit 10 is in the second state, the upper through-hole 103 is at least partially exposed, and the positioning block on the first sealing assembly 12 enters the positioning groove. On the one hand, the elements that have undergone internal sublimation and decomposition can be transported upward through the upper through-hole 103; on the other hand, as the control mounting rod 20 continues to rotate, the first sealing assembly 12 and the storage box 11 rotate synchronously with it, which can change the flow path of the sublimation and decomposition elements, improve the uniformity of the sublimation elements, and at the same time, the rotation of the storage box 11 can stir the silicon carbide powder 500 in the growth crucible 200, which can not only promote the sublimation of the silicon carbide powder 500, but also reduce the generation of C encapsulation.
[0081] In some embodiments of this utility model, reference is made to Figures 1 to 15 As shown, the projections of any two adjacent doped units 10 on the mounting rod 20 are arranged intersecting in the horizontal direction. Specifically, there is an included angle between any two adjacent doped units 10. In other words, for clarity, let's assume that the doped units 10 from top to bottom are the first doped unit, the second doped unit, the third doped unit, and so on. Taking the first and second doped units as examples, the included angle between the first and second doped units refers to the angle between the first doped unit and the projection of the second doped unit after the first doped unit is rotated by an angle A.
[0082] It is understandable that the cross arrangement of each doping unit 10 is more conducive to the uniform distribution of all the upper through holes 103 on each doping unit 10. In this way, the uniformity of the upward transport of sublimation elements can be further improved, and the effect of element doping or supplementation is more effective.
[0083] Reference Figures 1 to 15 As shown, the silicon carbide crystal growth apparatus 1000 according to an embodiment of the present invention 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 top-open receiving cavity 203. The crucible cover 202 is installed on the top of the crucible body 201, and a seed crystal 300 is installed at the bottom of the crucible cover 202. Silicon carbide powder 500 is placed in the receiving cavity 203. The doping mechanism 100 is rotatably installed in the receiving cavity 203. The doping mechanism 100 adopts the aforementioned doping mechanism. A heating component and a heat preservation structure can be provided on the outside of the growth crucible 200. The heating component can be an induction coil 400 for heating the growth crucible 200. The external structure of the growth crucible 200 is prior art and is not the focus of this invention, so it will not be described in detail here.
[0084] For example, refer to Figures 1 to 15As shown, in use, the doping mechanism 100 can be first adjusted to the open state to load silicon nitride powder 40 into it; after loading, the doping mechanism 100 is adjusted to the sealed state, and the entire doping mechanism 100 is placed in the growth crucible 200 for later use. It should be noted that the entire doping mechanism 100 can be completely placed inside the silicon carbide powder 500, and its vertical position within the growth crucible 200 is adjustable.
[0085] It is understood that, according to the silicon carbide crystal growth apparatus of this utility model embodiment, during crystal growth, under the action of the induction coil 400, the temperature of the crucible body 201 rises and transfers heat to the silicon carbide powder 500 inside it. On the one hand, the temperature of the silicon carbide powder 500 gradually rises until it sublimates. The sublimated silicon carbide vapor moves towards the crucible cover 202 under the action of the temperature gradient and achieves crystal growth at the seed crystal 300 on the crucible cover 202. On the other hand, the temperature of the doping mechanism 100 inside the growth crucible 200 also gradually rises and continues to transfer heat to the silicon nitride powder 40 inside it. The temperature of the silicon nitride powder 40 will also gradually rise and decompose into elemental nitrogen and silicon, such as silicon and nitrogen gas. In the early stages of crystal growth, the doping unit 10 is gradually opened from a sealed state (i.e., the first state) at a speed of V1. Nitrogen gas from the thermal decomposition of silicon nitride powder 40 continues to move upwards through the opening. On one hand, the nitrogen gas, along with silicon carbide vapor, moves towards the crucible cover 202 and is doped into the growing silicon carbide crystal, achieving nitrogen doping within the silicon carbide crystal to obtain a directional silicon carbide crystal. On the other hand, the nitrogen gas flow promotes the sublimation of the silicon carbide powder 500 above and further drives the sublimated silicon carbide vapor towards the seed crystal 300, accelerating the crystal growth rate. It is important to note that the nitrogen concentration decomposed within the doping unit 100 is high in the early stages. Controlling the size of the opening controls the sublimation rate of nitrogen and silicon, thereby controlling the nitrogen doping concentration during silicon carbide crystal growth and ultimately controlling the resistivity of the silicon carbide wafer.
[0086] As the reaction proceeds, in the later stages of crystal growth, the doped unit 10 continues to open at another rate V2 until it reaches the second state. Since the nitrogen concentration decomposed within the doped unit 10 is low in the later stages, the opening rate V2 is greater than V1 compared to the initial stage of crystal growth, resulting in a larger opening. This accelerates the sublimation rate of nitrogen and silicon, keeping the nitrogen concentration in the growth crucible 200 constant, thus maintaining the resistivity of the silicon carbide crystal in the later stages of crystal growth. Simultaneously, the silicon concentration from the silicon carbide powder 500 decomposed in the growth crucible 200 decreases while the carbon concentration increases, resulting in a carbon-rich state. Therefore, the opening increases rapidly, accelerating the diffusion of silicon from the doped unit 10 into the growth crucible 200 to replenish the silicon concentration. This replenished silicon can react with carbon to form silicon carbide for growth; additionally, it reduces the incorporation of C clusters into the crystal, thereby reducing defects such as C inclusions and microtubules.
[0087] According to the silicon carbide crystal growth apparatus of this invention, a doping mechanism 100 is provided inside the growth crucible 200. The state of the doping mechanism 100 is adjustable. The silicon nitride powder 40 inside can be thermally decomposed during the crystal growth process. By adjusting the doping mechanism 100, nitrogen and silicon elements can be replenished in the growth crucible 200 at different stages of crystal growth. In the early stage of crystal growth, nitrogen elements are doped into the growing silicon carbide crystal, achieving nitrogen doping within the silicon carbide crystal. Nitrogen doping can effectively reduce the resistivity of silicon carbide to obtain a directional silicon carbide crystal. 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 towards the seed crystal 300, accelerating the crystal growth rate. In the later stages of crystal growth, the concentration of nitrogen decomposed within the doping mechanism 100 is low. Therefore, controlling the doping mechanism 100 to continue opening to the second state at a faster rate accelerates the sublimation rate of nitrogen and silicon within it, ensuring a constant nitrogen concentration in the growth crucible 200 and maintaining a constant resistivity of the silicon carbide crystal in the later stages of crystal growth. Simultaneously, rapidly increasing the opening speed accelerates the sublimation of silicon within the doping mechanism 100 into the growth crucible 200, replenishing its concentration. This replenished silicon can react with carbon to form silicon carbide for growth and also reduces the incorporation of carbon clusters into the crystal, thereby reducing defects such as carbon inclusions and micropipes. Furthermore, the doping mechanism 100 can also act as a heat source, further heating the silicon carbide powder 500, resulting in more uniform heating and sublimation, thus improving the utilization rate of the silicon carbide powder 500.
[0088] In some embodiments of this invention, the weight ratio of silicon nitride powder 40 to silicon carbide powder 500 in the growth crucible 200 is 1:20 to 1:200. The optimal effect is achieved when the weight ratio of silicon nitride powder 40 to silicon carbide powder 500 is 1:20 to 1:200. In other words, the amount of silicon nitride powder 40 can be determined based on the amount of silicon carbide powder 500 loaded into the growth crucible 200 to optimize the replenishment of nitrogen and silicon elements, thereby obtaining silicon carbide crystals of better quality.
[0089] In some embodiments of this invention, the silicon carbide powder 500 has a particle size of 20-40 mesh, and the silicon nitride powder 40 has a particle size of 1-3 mesh; the diameter of the through-hole is 2-5 cm. When silicon nitride powder 40 and silicon carbide powder 500 are mixed in this mesh ratio, it can control the silicon nitride powder 40 to sublimate later than the silicon carbide powder 500, thereby avoiding increased early silicon enrichment and ensuring normal crystal growth.
[0090] In summary, this invention utilizes a doping mechanism 100 within the growth crucible 200, which contains silicon nitride powder 40. The silicon nitride powder 40 is used to dope nitrogen and replenish silicon during the growth of silicon carbide crystals. During loading, by adjusting the position of the dopant at different locations in the powder (i.e., the installation position of the doping mechanism) and its concentration (i.e., the weight of the silicon nitride powder), nitrogen and silicon can be replenished in the growth crucible 200 at different stages of crystal growth, thus growing qualified silicon carbide crystals. Specifically, in the early stage of crystal growth, nitrogen is doped into the growing silicon carbide crystal, effectively reducing its resistivity to obtain a directional silicon carbide crystal. Simultaneously, the airflow generated by the nitrogen promotes the sublimation of the silicon carbide powder 500 above and drives the sublimated silicon carbide vapor towards the seed crystal 300, accelerating the crystal growth rate. In the later stages of crystal growth, the concentration of nitrogen decomposed within the later-stage doping mechanism 100 is low. Therefore, controlling the doping mechanism 100 to continue opening to the second state at a faster rate accelerates the sublimation rate of nitrogen and silicon within it, ensuring a constant nitrogen concentration in the growth crucible 200 and maintaining a constant resistivity of the silicon carbide crystal in the later stages of crystal growth. Simultaneously, rapidly increasing the opening speed accelerates the sublimation of silicon within the doping mechanism 100 into the growth crucible 200, replenishing its concentration. This replenished silicon can react with carbon to form silicon carbide for growth; additionally, it reduces the intrusion of C clusters into the crystal, thereby reducing defects such as C inclusions and microtubes, improving crystal quality. Furthermore, the doping mechanism 100 can also act as a heat source, further heating the silicon carbide powder 500, resulting in more uniform heating and sublimation, thus improving the utilization rate of the silicon carbide powder 500.
[0091] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.
[0092] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.
[0093] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0094] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.
[0095] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0096] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.
Claims
1. A doping mechanism for silicon carbide crystals, characterized in that, include: Mounting rod; Doping unit, wherein the doping unit contains silicon nitride powder, and there are multiple doping units, which are spaced apart and mounted on the mounting rod; A power mechanism, which is connected to the mounting rod; The doping unit has a first state and a second state. In the first state, the doping unit is in a sealed state. In the second state, the doping unit is in a state that is at least partially open. Under the action of the power mechanism and the mounting rod, the doping unit switches between the first state and the second state.
2. The doping mechanism for silicon carbide crystals according to claim 1, characterized in that, The doped unit has a petal-shaped structure, and the doped unit includes: A storage box, the storage box having a petal-shaped structure, the storage box forming a petal-shaped hollow cavity, the storage box having an upper opening and a lower opening communicating with the hollow cavity at the center, and the storage box having several upper through holes communicating with the hollow cavity on the top wall; A first sealing assembly is disposed within the hollow cavity to completely block or at least partially expose the upper through hole; The storage box is fitted onto the mounting rod, and the first sealing assembly is inserted into the mounting rod. When the mounting rod rotates, the first sealing assembly rotates synchronously with the mounting rod, and the storage box remains stationary or rotates at a different speed than the mounting rod.
3. The doping mechanism for silicon carbide crystals according to claim 2, characterized in that, All the upper through holes are divided into multiple groups from the inside to the outside along the radial direction of the storage box. The line connecting all the upper through holes in each group is circular, and the number and position of the upper through holes on each petal in the storage box are the same.
4. The doping mechanism for silicon carbide crystals according to claim 2, characterized in that, The storage box includes: The box body has a petal-shaped box structure and defines a storage cavity with an open top; The lid is a petal-shaped plate that fits into the box body, and the lid is detachably installed on the top of the box body; The upper opening is located at the center of the lid, the lower opening is located at the center of the box body, and the upper through hole is located on each petal of the lid.
5. The doping mechanism for silicon carbide crystals according to claim 2, characterized in that, The first sealing component includes: A first mounting ring is fitted onto the mounting rod; The first baffle, there are multiple first baffles, all of which are evenly distributed along the circumferential direction of the first mounting ring, and the inner end of the first baffle is connected to the first mounting ring. In this configuration, all the first baffles are arranged one-to-one within each petal of the storage box and are positioned close to the top wall of the storage box; in the first state, all the first baffles completely block all the upper through holes; in the second state, all the first baffles are at least partially separated from the upper through holes.
6. The doping mechanism for silicon carbide crystals according to claim 2, characterized in that, The storage box has a positioning groove on its side wall, and the first sealing assembly has a positioning block that cooperates with the positioning groove.
7. The doping mechanism for silicon carbide crystals according to claim 1, characterized in that, The projections of any two adjacent doped units on the mounting rod are arranged crosswise in the horizontal direction.
8. A silicon carbide crystal growth apparatus, characterized in that, include: A growth crucible, comprising a crucible body and a crucible lid, the crucible body defining a top-open receiving cavity, the crucible lid being mounted on top of the crucible body, and a seed crystal being disposed at the bottom of the crucible lid; The doping mechanism is a doping mechanism for silicon carbide crystals as described in any one of claims 1 to 7, and the doping mechanism is rotatably mounted in the receiving cavity.
9. A silicon carbide crystal growth apparatus according to claim 8, characterized in that, The silicon carbide powder in the growth crucible has a particle size of 20-40 mesh, and the silicon nitride powder has a particle size of 1-3 mesh.
10. A silicon carbide crystal growth apparatus according to claim 8, characterized in that, The weight ratio of silicon nitride powder to silicon carbide powder in the growth crucible is 1:20 to 1:200.