Crucible structure for efficient silicon carbide single crystal growth

Abstract

The application discloses a high-efficiency silicon carbide single crystal growth crucible structure and belongs to the technical field of semiconductor material preparation. In order to solve the problems of low single-furnace output efficiency, insufficient raw material utilization rate, and difficult balance between capacity improvement and crystal quality in the existing PVT method silicon carbide growth, the crucible structure comprises an axial cylindrical crucible body, a raw material containing area is arranged in the axial middle part of the inner side of the crucible side wall, the inner walls of the top and bottom of the crucible are respectively fixed with top and bottom seeds which are symmetrically distributed along the axial direction, an axisymmetric barrel-shaped heating assembly is arranged around the outer periphery of the crucible, the axial middle part of the heating assembly corresponds to the position of the raw material containing area, and a high-temperature middle part and a symmetrically decreasing temperature field towards both ends are formed during work, so that the raw material sublimation gas phase can be transported to both seeds for crystallization in a bidirectional manner. The structure can be configured with a porous filter plate to protect the bottom seed, is suitable for three-section resistance heating or a middle tightly-wound induction coil, and can improve the single-furnace capacity and the raw material utilization rate while ensuring the crystal growth quality.

Description

Technical Field

[0001] This application belongs to the field of semiconductor material preparation technology, and more specifically relates to a crucible structure for efficient silicon carbide single crystal growth. Background Technology

[0002] Silicon carbide, as a third-generation wide-bandgap semiconductor material, has significant application value in high-voltage, high-frequency, and high-temperature power devices. Physical vapor transport (PVP) is currently the mainstream process for preparing large-size, high-quality silicon carbide single crystals. The crucible, as the support structure for crystal growth, directly determines the growth efficiency and finished product quality of the silicon carbide single crystal through its internal structure and the design of the associated thermal field.

[0003] Traditional PVT silicon carbide single crystal growth equipment generally adopts a unidirectional growth configuration with raw materials placed at the bottom and seed crystals placed at the top. The thermal field exhibits an axial distribution pattern of high temperature at the bottom and low temperature at the top. Some production increase schemes increase the output per furnace by arranging multiple crucibles in a single thermal field. Another segmented heating scheme uses multiple independently controlled heaters arranged around the crucible to adjust the temperature gradient distribution along the axial direction of the crucible.

[0004] The existing unidirectional growth structure can only produce one silicon carbide single crystal in a single growth cycle, resulting in low single-furnace output efficiency. The raw material gas phase components can only be utilized by a single crystallization surface, leaving room for improvement in raw material utilization. On the other hand, the multi-crucible production increase scheme will destroy the axisymmetric characteristics of the thermal field of a single crucible, which will easily lead to an increase in internal defects in the crystal, making it impossible to balance production capacity increase and crystal growth quality. Summary of the Invention

[0005] This application addresses the problems of low single-furnace output efficiency, insufficient raw material utilization, and difficulty in balancing capacity improvement and crystal quality in existing PVT-based silicon carbide growth methods. It provides a crucible structure for high-efficiency silicon carbide single crystal growth, comprising: The crucible body is cylindrical with an axial orientation. The raw material receiving area is located at the axial center of the crucible body; The top seed crystal is fixed to the top inner wall of the crucible body; The bottom seed crystal is fixed to the bottom inner wall of the crucible body, and the top seed crystal and the bottom seed crystal are symmetrically distributed along the axial direction of the crucible body; The heating component has an axisymmetric barrel-shaped structure and is arranged around the outer periphery of the crucible body. The axial center position of the heating component corresponds to the axial position of the raw material receiving area. When the heating component is working, it forms a temperature field inside the crucible body with the highest temperature in the axial center and a symmetrically decreasing temperature towards the top and bottom, so that the gas phase components formed by the sublimation of the raw materials in the raw material containing area can be transported and crystallized bidirectionally to the top seed crystal and the bottom seed crystal respectively.

[0006] One feasible implementation also includes a porous filter plate; The porous filter plate is disposed on the side of the bottom seed crystal facing the raw material receiving area; The outer peripheral edge of the porous filter plate is connected to the inner wall of the crucible body, and the surface of the porous filter plate is parallel to the crystal surface of the bottom seed crystal.

[0007] In one feasible implementation, the raw material receiving area extends continuously along the inner circumferential side of the side wall of the crucible body, forming a closed annular cavity structure. The axial midpoint of the raw material receiving area coincides with the axial midpoint of the crucible body.

[0008] In one possible implementation, the top seed crystal is fixed to the central region of the inner top wall of the crucible body; The bottom seed crystal is fixed to the central region of the inner wall of the bottom of the crucible body; The geometric center of the top seed crystal and the geometric center of the bottom seed crystal are both located on the central axis of the crucible body.

[0009] In one feasible implementation, the heating assembly includes a side heater; The side heater has a cylindrical structure and is fixed around the outside of the side wall of the crucible body; The axial coverage area of ​​the side heater corresponds to the axial coverage area of ​​the raw material receiving area.

[0010] In one feasible implementation, the heating assembly further includes a top heater and a bottom heater; The top heater is fixedly disposed on the outer top of the crucible body, and the bottom heater is fixedly disposed on the outer bottom of the crucible body; The top heater, the side heater, and the bottom heater are arranged independently of each other.

[0011] In one feasible implementation, the heating component is a spiral induction coil, which is coaxially wrapped around the outer periphery of the crucible body; The coil turn pitch in the axial middle section of the spiral induction coil is smaller than the coil turn pitch in the axial end sections.

[0012] In one feasible implementation, the heating component is a circumferentially continuous integral cylindrical structure with no splicing breaks or assembly gaps in the circumferential direction.

[0013] In one feasible implementation, the crucible body is an axisymmetric cylindrical closed structure with closed ends at the top and bottom, forming an independent growth chamber inside.

[0014] In one feasible implementation, the center of the porous filter plate is coaxially arranged with the center of the bottom seed crystal, and the surface of the porous filter plate covers the entire crystal surface area of ​​the bottom seed crystal.

[0015] Based on the above, the high-efficiency silicon carbide single crystal growth crucible structure provided in this application, through its central feeding and top-bottom symmetrical double-seed crystal configuration, combined with an axisymmetric barrel-shaped heating assembly creating a central high-temperature field that symmetrically decreases towards both ends, enables bidirectional synchronous growth of silicon carbide single crystals. Two single crystals can be produced simultaneously in a single growth cycle, improving single-furnace output efficiency. After sublimation, a single batch of raw material can be bidirectionally transported to both crystal interfaces, expanding the effective utilization path of the raw material and improving its utilization rate. Simultaneously, the bidirectional flow splitting effect dilutes the silicon atmosphere enrichment on a single growth surface, optimizing the stability of the crystal growth rate. The structure retains the axisymmetric thermal field characteristics of a single crucible, and the circumferentially continuous heating structure ensures circumferential temperature field uniformity, reducing radial thermal stress and defect density in the crystal, thus improving production capacity while ensuring single crystal growth quality. The porous filter plate on the bottom seed crystal side intercepts settled solid particles, improving the cleanliness of the bottom growth environment without hindering the normal transport of gaseous components. The solution is compatible with both resistance heating and induction heating. The three-stage independent resistance heating can achieve precise temperature field control and optimize crystallization quality and thermal stress state. The sealed crucible chamber can maintain a stable growth environment and reduce external environmental interference. The overall structure is adapted to the needs of large-scale production. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the implementation of the invention and, together with the description, serve to explain the principles of the embodiments of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0017] Figure 1 This is a schematic diagram of the crucible structure for high-efficiency silicon carbide single crystal growth shown in the embodiments of this application; Figure 2 This is a schematic diagram of the crucible structure for efficient silicon carbide single crystal growth, as shown in another embodiment of this application.

[0018] Label Explanation: 1-Cruise body; 2-Raw material holding area; 3-Top seed crystal; 4-Bottom seed crystal; 5-Heating component; 6-Porous filter plate; 51-Side heater; 52-Top heater; 53-Bottom heater. Detailed Implementation

[0019] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the embodiments of the invention will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of how embodiments of the invention are carried out.

[0020] Existing PVT (Polymer Transformation) silicon carbide single crystal growth apparatuses generally employ a growth configuration where the raw material is placed at the bottom and the seed crystal at the top, exhibiting a unidirectional thermal distribution with high temperature at the bottom and low temperature at the top. During crystal growth, the raw material at the bottom sublimates upon heating, forming silicon carbide vapor components, which are transported to the seed crystal at the top under the drive of the concentration gradient. Upon reaching the seed crystal surface, they supercool and crystallize, achieving single crystal growth. This unidirectional growth structure has significant limitations in practical applications. Only one silicon carbide single crystal can be produced in a single growth cycle, resulting in low single-furnace output efficiency. The raw material can only be transported along a single direction and utilized by a single crystallization plane, leading to a large amount of vapor components easily depositing in the non-crystalline region of the inner wall of the chamber, leaving considerable room for improvement in raw material utilization. Simultaneously, during unidirectional transport, the vapor components continuously accumulate in a single direction, easily resulting in excessively high local concentrations of Si atmosphere, which negatively impacts the stability of the crystal growth rate. In addition, some existing solutions increase production capacity by placing multiple crucibles in a single thermal field. However, this approach disrupts the axisymmetric characteristics of the single crucible thermal field, which cannot be well matched with the growth characteristics of silicon carbide single crystals. This can easily lead to an increase in internal defects in the crystal and a decrease in growth quality, making it impossible to meet both the requirements of production capacity and quality.

[0021] Based on the problems of low single-furnace output efficiency, insufficient raw material utilization, and difficulty in balancing capacity improvement and crystal quality in the existing technologies, this embodiment provides a crucible structure for high-efficiency silicon carbide single crystal growth. Through a symmetrical double-seed crystal layout and a central high-temperature bidirectional transport thermal field architecture, it achieves simultaneous growth of two crystals in a single furnace while retaining the advantages of the axisymmetric thermal field of a single crucible. This significantly improves growth efficiency and raw material utilization while ensuring crystal growth quality.

[0022] The crucible structure for high-efficiency silicon carbide single crystal growth in this embodiment is based on... Figure 1 As shown, it includes a crucible body 1, a raw material containing area 2, a top seed crystal 3, a bottom seed crystal 4, and a heating component 5.

[0023] The crucible body 1 is an axially oriented cylindrical shape, which may include components such as the crucible cylinder and crucible lid, providing a support base for the internal growth space and various functional components. In one embodiment, the axial direction of the crucible body 1 is vertical, and its cylindrical structure has complete rotational symmetry characteristics, which can adapt to a circumferentially uniform heating environment and ensure that heat is uniformly transferred to the internal chamber circumferentially. The inner wall of the crucible body 1 can serve as a raw material receiving area and a mounting surface for the seed crystal, providing a stable mounting reference for each internal component. Furthermore, the crucible body 1 can be made of high-temperature resistant graphite material to adapt to the high-temperature process environment of silicon carbide single crystal growth, while also possessing good thermal conductivity to ensure that external heating heat can be efficiently and uniformly transferred to the internal chamber, providing a stable thermal environment for raw material sublimation and crystal growth.

[0024] The raw material receiving area 2 is located at the axial center of the crucible body 1 and is used to store silicon carbide growth raw materials. The axial position of the raw material receiving area 2 corresponds to the middle section of the axial direction of the crucible body 1, so that the raw material is located at the center of the crucible's axial direction. Arranging the raw material receiving area 2 at the axial center ensures that the raw material is located in the highest temperature region of the temperature field, ensuring that the raw material can be fully heated and sublimated, and avoiding the problem of incomplete sublimation and insufficient production of effective components due to being in a low temperature region.

[0025] The axial width of the raw material receiving area 2 can be adjusted according to the raw material loading amount and the coverage of the high-temperature zone to ensure that all raw materials are within the effective sublimation temperature range, maximizing the effective utilization rate of raw materials and reducing the residue of insufficiently sublimated raw materials. Based on the centrally arranged raw material area configuration, the gaseous components formed after the raw materials sublimate can diffuse and transport in both the top and bottom directions simultaneously, breaking the limitation of gas phase transport in only one direction in traditional unidirectional growth structures. This provides a stable material basis for bidirectional synchronous crystallization and expands the effective utilization path of raw materials.

[0026] The top seed crystal 3 is fixed to the top inner wall of the crucible body 1, and the bottom seed crystal 4 is fixed to the bottom inner wall of the crucible body 1. The top seed crystal 3 and the bottom seed crystal 4 are symmetrically distributed along the axial direction of the crucible body 1. In one embodiment, the growth crystal face of the top seed crystal 3 faces the internal cavity of the crucible body 1, and the growth crystal face of the bottom seed crystal 4 also faces the internal cavity of the crucible body 1. The crystal faces of the two are arranged opposite to each other, corresponding to two independent crystallization interfaces, respectively. The axially symmetrical dual-seed crystal layout allows the two seed crystals to be located in the upper and lower low-temperature zones of the temperature field, while simultaneously satisfying the supercooling conditions required for crystal growth, providing a core structural basis for bidirectional synchronous growth.

[0027] Understandably, a symmetrically distributed seed crystal layout corresponds to a symmetrical temperature field environment, ensuring high consistency in growth temperature, gas concentration, and other conditions at the two seed crystals. This guarantees similar growth quality and rate for both crystals, facilitating process control and quality consistency management during production. Compared to traditional single-seed crystal growth structures, a dual-seed crystal layout can simultaneously prepare two silicon carbide single crystals within a single growth cycle, significantly increasing single-furnace output efficiency without requiring an expansion of furnace volume or thermal field scale, thus significantly reducing energy consumption and cost per unit capacity.

[0028] The heating component 5 has an axisymmetric barrel-shaped structure and is arranged around the outer periphery of the crucible body 1. The axial center position of the heating component 5 corresponds to the axial position of the raw material receiving area 2. In one embodiment, the barrel-shaped structure of the heating component 5 is coaxially arranged with the crucible body 1, surrounding and enclosing the outer periphery of the side wall of the crucible body 1, and can apply a uniform circumferential heating effect to the crucible body 1. The heating power density of the heating component 5 exhibits a distribution characteristic of high in the middle and low at both ends along the axial direction. The high-power section in the middle of its axial direction corresponds one-to-one with the axial position of the raw material receiving area 2, which can form a high-temperature region in the middle of the axial direction inside the crucible, providing sufficient heat support for the sublimation of the raw material. The axisymmetric barrel-shaped heating structure can ensure that the heating intensity is consistent in all circumferential positions of the crucible body 1, thereby forming a uniform circumferential temperature field inside the crucible, matching the isotropic growth requirements of silicon carbide single crystals, and avoiding differences in crystal growth rate and internal stress imbalance caused by uneven circumferential temperature field.

[0029] When the heating component 5 is working, heat is conducted to the internal chamber through the side wall of the crucible body 1, forming a temperature field inside the crucible body 1 with the highest temperature in the axial center and a symmetrical decrease towards the top and bottom. This temperature field distribution breaks the traditional design paradigm of PVT growth with high temperature at one end and low temperature at the other, forming a thermodynamic structure of a high-temperature source and dual crystallization planes, providing a core thermodynamic basis for bidirectional synchronous crystallization. Under the action of this temperature field, the raw material in the raw material containing area is heated and sublimated to form gaseous components. Driven by the concentration gradient and temperature gradient in the chamber, the gaseous components can be transported bidirectionally to the top seed crystal and the bottom seed crystal, respectively. After reaching the seed crystal surface, crystallization growth is completed under supercooled conditions.

[0030] Based on the bidirectional transport growth mode, a single batch of raw material can be simultaneously supplied to two crystallization interfaces for crystal growth. This significantly expands the effective utilization path of the raw material, resulting in a substantial improvement in raw material utilization compared to unidirectional growth structures. It also reduces the ineffective deposition and waste of gaseous components in amorphous regions. Simultaneously, the bidirectional flow of gaseous components dilutes the Si atmosphere enrichment on a single growth surface, further improving the rate stability of the crystal growth process and reducing growth defects and interface unevenness caused by component concentration fluctuations. Furthermore, this structure retains the axisymmetric thermal field design of a single crucible, eliminating the need for multiple crucibles to divide the thermal field. This allows for better matching of the growth characteristics of silicon carbide single crystals, improving production capacity while ensuring crystal growth quality, and avoiding the problems of decreased temperature field uniformity and crystal quality degradation associated with multi-crucible solutions.

[0031] In some embodiments of this application, the crucible structure further includes a porous filter plate 6. The porous filter plate 6 is disposed on the side of the bottom seed crystal 4 facing the raw material receiving area 2, within the axial space between the bottom seed crystal 4 and the raw material receiving area 2. The surface of the porous filter plate 6 can be arranged horizontally and parallel to the crystal surface of the bottom seed crystal 4, which ensures that the axial distance between all parts of the filter plate and the surface of the seed crystal is consistent. This allows the gas phase components passing through the porous filter plate 6 to uniformly reach all areas of the seed crystal surface, avoiding uneven gas phase concentration distribution due to distance differences and ensuring the radial growth uniformity of the bottom crystal.

[0032] The outer peripheral edge of the porous filter plate 6 is fixedly connected to the inner sidewall of the crucible body 1, achieving stable support and fixation through the crucible sidewall. Specifically, the outer contour dimensions of the porous filter plate 6 match the inner cross-sectional dimensions of the crucible body 1, ensuring that the circumferential edge of the filter plate can be completely fitted and fixed to the inner wall of the crucible, preventing gaps at the edges from allowing solid particles to leak through side gaps and ensuring the circumferential integrity of the filtration and protection. The porous graphite material possesses excellent high-temperature resistance and chemical stability, allowing it to operate stably for extended periods in the high-temperature environment of silicon carbide growth without reacting with gaseous components to introduce additional impurities. It also possesses sufficient structural strength to stably support the intercepted solid particles without deforming or failing at high temperatures.

[0033] The porous filter plate 6 has an interconnected pore structure. The pore size allows silicon carbide vapor phase components to pass freely while preventing solid graphite particles or raw material particles larger than the pore size from settling downwards. Based on this structural characteristic, solid particles that detach from the raw material receiving area 2 are intercepted by the upper surface of the porous filter plate 6 when moving downwards under gravity, preventing them from directly contacting the crystal face of the bottom seed crystal 4. This effectively avoids impurity contamination and defect induction caused by solid particles to the seed crystal and the growing crystal. Simultaneously, the vapor phase components can smoothly pass through the filter plate through the pore structure, continuously transporting them to the surface of the bottom seed crystal 4, ensuring unimpeded material supply for crystal growth, maintaining a normal growth rate for the bottom crystal, and keeping the growth progress of the bottom crystal similar to that of the top crystal.

[0034] Understandably, the design of setting a filter plate only on the bottom seed crystal side is a targeted optimization to adapt to the bidirectional temperature field configuration of the central raw material area. It not only accurately solves the problem of material contamination at the bottom seed crystal, but also avoids adding redundant structures at the top seed crystal, reducing unnecessary flow field interference and increased manufacturing costs. At the same time, it ensures a more direct and smooth gas phase transport environment at the top seed crystal, ensuring the growth efficiency of the top crystal and achieving a balance between protection and growth efficiency.

[0035] Therefore, by adding a porous filter plate 6, this embodiment can effectively improve the cleanliness of the bottom seed crystal growth environment without affecting the bidirectional gas phase transport efficiency, reduce the probability of crystal defects caused by particulate contamination, and further improve the quality and yield of the finished crystal.

[0036] In some embodiments of this application, the raw material receiving area 2 extends continuously along the inner circumferential sidewall of the crucible body 1, forming a closed annular cavity structure. The annular raw material receiving area 2, arranged continuously along the inner circumference of the crucible, compared to the method of filling the entire central cavity of the crucible body 1 with raw material, allows for uniform filling of the raw material in the circumferential direction, ensuring consistent raw material loading and sublimation rates throughout the circumference, and creating a uniform circumferential gas phase concentration field within the cavity. This continuous annular arrangement of the raw material precisely matches the axisymmetric heating component 5 and the temperature field distribution, ensuring completely consistent heating conditions and uniform sublimation rates at all circumferential locations. This avoids excessive or insufficient sublimation of local raw materials, improves overall raw material utilization efficiency, and reduces the problem of premature depletion or excessive residue in certain areas.

[0037] The axial midpoint of the raw material receiving area 2 coincides with the axial midpoint of the crucible body 1. This coaxial alignment ensures that the center of the raw material receiving area 2 corresponds to the center of the high-temperature zone, guaranteeing that the upper and lower halves of the raw material receiving area 2 are in a symmetrical temperature environment, resulting in a more balanced sublimation rate at all axial positions of the raw material. It is understood that the axial midpoint coincidence design allows the initial concentration and dynamic conditions for the transport of gaseous components generated by the sublimation of the raw material to the top and bottom to remain symmetrical, which is beneficial for maintaining the balance of the bidirectional transport process. This ensures that the gas supply intensity at the top seed crystal 3 and the bottom seed crystal 4 is consistent, thereby achieving synchronous and equal-rate growth of the two crystals, reducing the growth difference between the top and bottom crystals, and lowering the difficulty of process control.

[0038] In some embodiments of this application, the top seed crystal 3 is fixed to the central region of the inner top wall of the crucible body 1, and the bottom seed crystal 4 is fixed to the central region of the inner bottom wall of the crucible body 1. In one embodiment, the central region of the top inner wall corresponds to the geometric center of the top end face of the crucible, and the central region of the bottom inner wall corresponds to the geometric center of the bottom end face of the crucible. The installation reference of the seed crystal is aligned with the center of the end face, ensuring that the seed crystal is located in the core uniform temperature zone of the end face. Arranging the seed crystal in the central region of the end face allows the seed crystal to be located on the central axis of the axisymmetric temperature field. The radial temperature distribution on the surface of the seed crystal exhibits a symmetrical distribution with the center as the origin, and the temperature gradient at each radial position is consistent, ensuring a uniform radial growth rate of the crystal and reducing radial morphology deviations and edge growth abnormalities.

[0039] The geometric centers of both the top seed crystal 3 and the bottom seed crystal 4 are located on the central axis of the crucible body 1. This coaxial arrangement ensures that the two seed crystals are completely situated on the symmetrical plane of the temperature field. The temperature field environment and gas phase concentration environment of both crystals exhibit high axial symmetry, guaranteeing that the growth conditions of the top and bottom crystals are completely consistent, resulting in good consistency in growth rate and crystal quality. It is understandable that the centrally coaxial seed crystal layout maximizes the utilization of the uniform region of the axially symmetrical temperature field, reduces the impact of edge temperature field fluctuations on crystal growth, effectively reduces radial thermal stress within the crystal, minimizes the generation of defects such as dislocations and microtubes, and improves the crystallization quality of the single crystal. Simultaneously, the coaxially symmetrical dual-seed crystal layout reduces the complexity of process debugging, facilitating the simultaneous control of the growth process of both crystals through unified temperature field parameters, and improving the process stability of mass production.

[0040] In some embodiments of this application, reference is made to Figure 2As shown, the heating assembly 5 includes a side heater 51, which has a cylindrical structure and is fixed around the outer side wall of the crucible body 1. The cylindrical side heater 51 is coaxially arranged with the crucible body 1, and its inner wall is arranged opposite to the outer side wall of the crucible body 1. Heat is uniformly applied to the side wall of the crucible through thermal radiation and thermal conduction, and then conducted to the internal chamber from the side wall. The overall cylindrical structure ensures that the circumferential heating intensity is completely consistent, avoids the appearance of weak heating areas in the circumferential direction, ensures the circumferential uniformity of the internal temperature field, and matches the isotropic growth requirements of silicon carbide single crystals.

[0041] The axial coverage area of ​​the side heater 51 corresponds to the axial coverage area of ​​the raw material receiving area 2. This arrangement allows the heating area of ​​the side heater 51 to precisely correspond to the axial position of the raw material receiving area, concentrating the heating power on the raw material section, efficiently increasing the temperature of the raw material area, ensuring sufficient and uniform sublimation of the raw material, reducing ineffective heat loss, and improving heating efficiency and energy utilization. Alternatively, the axial length of the side heater 51 can be matched with the axial length of the raw material receiving area 2, or slightly larger, to ensure that the entire raw material area is within a uniform heating range and to avoid insufficient temperature and incomplete sublimation at the edges of the raw material area.

[0042] The use of a resistance-type side heater configuration allows for more uniform heating of the silicon carbide raw material, making the sublimation process more stable and controllable, thereby improving the effective utilization rate of the raw material. Simultaneously, it helps maintain a stable crystal growth rate, reducing growth fluctuations and interface defects. The cylindrical side heater also possesses complete axisymmetry characteristics, forming a good fit with the cylindrical structure of the crucible, jointly creating a uniform circumferential temperature field and ensuring the circumferential uniformity of crystal growth.

[0043] Therefore, this embodiment uses a cylindrical side heater with a resistance heating structure to achieve precise and uniform heating of the raw material area, improve the heating uniformity and sublimation stability of the raw material, and further optimize the raw material utilization rate and the stability of crystal growth rate.

[0044] In some embodiments of this application, the heating assembly 5 further includes a top heater 52 and a bottom heater 53. The top heater 52 is fixedly disposed on the outer top of the crucible body 1, and the bottom heater 53 is fixedly disposed on the outer bottom of the crucible body 1. The top heater 52 covers the outer region of the top end face of the crucible and can provide heating compensation for the top of the crucible, adjusting the temperature level of the top seed crystal region. The bottom heater 53 covers the outer region of the bottom end face of the crucible and can provide heating compensation for the bottom of the crucible, adjusting the temperature level of the bottom seed crystal region. The top heater and the bottom heater can apply independent heating to the end face regions where the top and bottom seed crystals are located, respectively, flexibly adjusting the temperature gradient and supercooling of the seed crystal interface to adapt to different growth rates and crystal quality requirements.

[0045] The top heater 52, side heater 51, and bottom heater 53 are arranged independently, and each can be controlled independently by its power. This independent arrangement of the three heaters allows for zoned temperature field control. By adjusting the power of the side heaters, the temperature level in the central high-temperature zone can be controlled, thereby adjusting the sublimation rate and gas concentration of the raw material. By adjusting the power of the top and bottom heaters, the temperatures in the top and bottom low-temperature zones can be controlled respectively, allowing for flexible adjustment of the temperature gradient and supercooling at the seed crystal interface to adapt to different growth rate requirements. At different stages of crystal growth, the power parameters of each heater can be adjusted according to changes in the growth interface and quality requirements, achieving dynamic temperature field control throughout the entire growth cycle.

[0046] By coordinating the top and bottom heaters, the thermal field within the seed crystal interface can be more precisely controlled, optimizing the temperature distribution at the crystallization interface and further improving crystallization quality. Simultaneously, it effectively reduces internal thermal stress and minimizes thermal defects. Understandably, the three-stage independently heated structure allows for separate calibration of the growth environment for the top and bottom seed crystals, compensating for temperature field deviations caused by structural assembly, material differences, and other factors, ensuring consistent growth rate and quality in both directions.

[0047] In some embodiments of this application, the heating component 5 is a spiral induction coil, which is coaxially wrapped around the outer periphery of the crucible body 1. The spiral induction coil extends spirally along the axial direction of the crucible body 1 and is coaxially arranged with the crucible body 1. It can generate an alternating magnetic field after an alternating current is applied, causing the crucible body 1 to induce Joule heating. The coaxial arrangement ensures that the magnetic field generated by the coil is uniformly distributed in the circumferential direction, thereby making the circumferential heating of the crucible uniform, ensuring the circumferential symmetry of the internal temperature field, and matching the isotropic growth requirements of silicon carbide single crystals.

[0048] Furthermore, the coil turn pitch in the axial middle section of the spiral induction coil of heating component 5 is smaller than that in the axial end sections. In other words, the coil uses a dense winding design in the axial middle and a sparse winding design at the ends. The more coil turns per unit axial length, the higher the corresponding magnetic field strength, and the greater the induced heating power of the crucible. Therefore, the densely wound section in the middle can generate higher heating power, forming a high-temperature region in the axial middle inside the crucible; the sparsely wound sections at the ends have lower heating power, corresponding to lower-temperature regions at both ends, thus constructing an axial temperature field distribution that is high in the middle and symmetrically decreases towards both ends.

[0049] Understandably, the gradient of coil turn pitch can be adjusted according to the temperature gradient requirements of the target temperature field. By adjusting the turn pitch density at different axial positions, the heating power at each axial position can be precisely controlled, thereby matching the target temperature field curve. The densely wound induction coil design in the middle can concentrate heating energy at the axial position corresponding to the raw material containing area, ensuring full sublimation of the raw material, while naturally forming low-temperature crystallization zones at both ends. No additional cooling structure is required, the overall structure is simple and reliable, maintenance costs are low, and it is suitable for large-scale production applications.

[0050] In some embodiments of this application, the heating component 5 is a circumferentially continuous integral cylindrical structure with no splicing breaks or assembly gaps in the circumference. The integral cylindrical structure can be manufactured using a one-piece molding process, resulting in a complete and continuous circumferential structure without any structural breaks such as splicing seams, assembly gaps, or monitoring windows. This circumferentially continuous heating structure ensures that the heating power is completely uniform throughout the entire circumference, eliminating localized differences in heating intensity. This, in turn, ensures a highly consistent heating temperature at all circumferential locations on the crucible sidewall, guaranteeing circumferential uniformity of the temperature field from the heat source end and reducing circumferential temperature field deviations at their source.

[0051] Based on the circumferentially uninterrupted integral heating structure, the circumferential temperature deviation inside the crucible can be controlled within an extremely small range, forming a highly uniform circumferential temperature field that perfectly matches the isotropic growth requirements of spherical single crystals. The uniform circumferential temperature field can effectively reduce the radial temperature gradient of the crystal, reduce the radial thermal stress inside the crystal, thereby reducing the probability of defects such as microtubes and dislocations, and improving the crystallization quality of the single crystal.

[0052] Understandably, the core design of the integral continuous cylindrical heating structure lies in creating a highly rotationally symmetrical temperature field, which fully serves the uniformity requirements of crystal growth itself. There is no need to set up circumferential openings for additional functions such as adapting to external monitoring equipment, thus avoiding the destruction of temperature field uniformity by openings and maximizing the quality advantages of crystal growth.

[0053] In some embodiments of this application, the crucible body 1 is an axisymmetric cylindrical closed structure with closed top and bottom ends, forming an independent growth chamber inside. The top and bottom of the crucible body 1 are completely closed structures, which, together with the sidewalls, form a complete closed chamber, containing the growth raw materials and seed crystals within an independent internal space, physically isolating them from the external furnace environment. This closed chamber structure maintains stable gas pressure within the growth environment, ensuring a stable and controllable concentration gradient of gaseous components, providing a stable thermodynamic and material transport environment for crystal growth, reducing the interference of external gas pressure fluctuations on the growth process, and improving the repeatability of the growth process.

[0054] The axisymmetric cylindrical sealed structure can be well adapted to the external axisymmetric heating components, ensuring that heat is uniformly conducted from the side walls to the internal chamber, and the axisymmetric characteristics of the temperature field are not disrupted by the chamber structure. The closed ends at the top and bottom provide stable mounting surfaces for the top and bottom seed crystals, respectively. At the same time, the closed ends also play a certain role in heat preservation and temperature uniformity, buffering the impact of external environmental temperature fluctuations on the internal seed crystal area, improving the temperature stability of the seed crystal area, and reducing growth defects caused by temperature fluctuations.

[0055] An independent growth chamber can prevent impurity particles from the external environment from entering the chamber and contaminating the seed crystal and the grown crystal. At the same time, it can prevent the gas phase components in the chamber from escaping outward, ensuring that all gas phase components generated by the sublimation of raw materials are used for bidirectional crystal growth, further improving the effective utilization rate of raw materials and reducing raw material waste.

[0056] In some embodiments of this application, the center of the porous filter plate 6 and the center of the bottom seed crystal 4 are coaxially arranged, and the geometric centers of both are located on the central axis of the crucible body 1. This coaxial alignment ensures that the relative positions of the filter plate and the seed crystal are completely symmetrical in the radial direction. The filter plate provides consistent protection to the seed crystal in all radial directions, guaranteeing uniform filtration and protection at all circumferential positions of the seed crystal. This avoids insufficient protection on one side and redundant protection on the other, improving the balance and reliability of protection, and ensuring consistent cleanliness of the growth environment at all circumferential positions of the crystal.

[0057] The porous filter plate 6 covers the entire crystal surface area of ​​the bottom seed crystal 4. That is, in the projection direction perpendicular to the axial direction, the projection range of the porous filter plate 6 completely covers the crystal surface projection range of the bottom seed crystal 4, and the radial dimension of the filter plate is greater than or equal to the radial dimension of the crystal surface of the bottom seed crystal 4. This full-coverage design ensures that all downward-sinking solid particles are intercepted by the filter plate before reaching the seed crystal surface, eliminating blind spots and providing comprehensive particle protection for the bottom seed crystal, thus completely eliminating the risk of particle contamination in the edge areas.

[0058] The porous filter plate 6 can be configured such that its outer edge extends to the inner wall of the crucible. While being fixed to the side wall, this maximizes the coverage area of ​​the filter plate, ensuring the entire seed crystal area is within the protected zone and preventing particle leakage due to edge gaps. This fully covered and coaxial filter plate structure, while ensuring uniform passage of gaseous components, completely isolates the bottom seed crystal from contamination by gravity-sedimented solid particles, maximizing the protective effect of the filter plate and adapting to the growth requirements of large-size crystals.

[0059] Therefore, this embodiment, through the coaxial and fully covered porous filter plate configuration, can achieve blind-zone-free particle protection for the bottom seed crystal, further improve the cleanliness of the bottom crystal growth environment, reduce crystal defects caused by particle contamination, and improve the yield and quality consistency of the finished crystal.

[0060] As can be seen from the above embodiments, the crucible structure for high-efficiency silicon carbide single crystal growth provided in this application, in actual use, firstly, fills the silicon carbide growth raw material into the raw material receiving area 2, and then fixes the top seed crystal 3 and the bottom seed crystal 4 to the corresponding positions of the top inner wall and bottom inner wall of the crucible body 1, respectively, completing the assembly of the internal components of the crucible. Then, the assembled crucible body 1 is placed inside the heating assembly 5, so that the heating assembly 5 is coaxially surrounding the outer periphery of the crucible body 1, and the axial center of the heating assembly 5 is aligned with the axial position of the raw material receiving area 2, completing the assembly of the overall structure. Finally, the overall structure is placed inside the growth furnace, ready to carry out the growth process.

[0061] After the heating component 5 is activated, the heat generated by the heating component 5 is conducted to the internal chamber through the side wall of the crucible body 1. The temperature inside the crucible gradually increases, and after the temperature field stabilizes, a stable temperature field distribution is established with the highest temperature in the axial center and a symmetrical decrease towards the top and bottom. As the temperature continues to rise to the raw material sublimation temperature, the silicon carbide raw material in the raw material containing area 2 is heated and sublimated, forming a gaseous substance containing silicon and carbon components. Driven by the temperature gradient and concentration gradient in the chamber, the gaseous components are transported bidirectionally in two directions: the top seed crystal 3 at the top and the bottom seed crystal 4 at the bottom. When the gaseous components reach the seed crystal surface at a lower temperature, they reach a supersaturated state and crystallize and deposit on the seed crystal surface, realizing the bidirectional synchronous growth of silicon carbide single crystals.

[0062] During growth, the symmetrically distributed temperature field and the dual-seed crystal structure ensure highly consistent growth conditions for both the top and bottom crystals, allowing for simultaneous growth and facilitating unified control of the growth cycle. For the scheme with a porous filter plate 6, the porous filter plate 6 above the bottom seed crystal 4 continuously intercepts descending solid particles while allowing gaseous components to pass smoothly. This ensures a stable supply of growth material to the bottom crystal while maintaining the cleanliness of the bottom seed crystal surface, reducing particle defects, and improving the growth quality of the bottom crystal. For the scheme with a three-stage resistance heater, the temperature field distribution can be adjusted in real time by regulating the power of the side heater 51, top heater 52, and bottom heater 53, adapting to the process requirements of different growth stages, finely controlling the crystal growth rate and crystallization quality, and optimizing the internal stress state of the crystal. For the scheme using induction coil heating, the centrally tightly wound coil structure naturally forms a high-temperature zone, efficiently driving the material sublimation and bidirectional transport process. The structure is simple, reliable, and has low maintenance costs. After growth is complete, stop the heating output of heating component 5. After the crucible cools down to room temperature with the furnace, two silicon carbide single crystals can be taken out from the top and bottom of the crucible respectively, completing a single growth cycle.

[0063] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein.

[0064] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A crucible structure for efficient silicon carbide single crystal growth, characterized in that, include: The crucible body (1) is a cylindrical shape arranged axially. The raw material receiving area (2) is located at the axial center of the crucible body (1); The top seed crystal (3) is fixed to the top inner wall of the crucible body (1); Bottom seed crystal (4) is fixed to the bottom inner wall of the crucible body (1), and the top seed crystal (3) and the bottom seed crystal (4) are symmetrically distributed along the axial direction of the crucible body (1). The heating component (5) has an axisymmetric barrel-shaped structure and is arranged around the outer periphery of the crucible body (1). The axial center position of the heating component (5) corresponds to the axial position of the raw material receiving area (2). When the heating component (5) is working, it forms a temperature field inside the crucible body (1) with the highest temperature in the middle of the axis and a symmetrical decrease towards the top and bottom, so that the gas phase components formed by the sublimation of the raw materials in the raw material containing area (2) can be transported bidirectionally to the top seed crystal (3) and the bottom seed crystal (4) and crystallize.

2. The crucible structure for high-efficiency silicon carbide single crystal growth according to claim 1, characterized in that, It also includes a porous filter plate (6); The porous filter plate (6) is disposed on the side of the bottom seed crystal (4) facing the raw material receiving area (2); The outer peripheral edge of the porous filter plate (6) is connected to the inner sidewall of the crucible body (1), and the plate surface of the porous filter plate (6) is parallel to the crystal surface of the bottom seed crystal (4).

3. The crucible structure for high-efficiency silicon carbide single crystal growth according to claim 1, characterized in that, The raw material receiving area (2) extends continuously along the inner circumferential side of the side wall of the crucible body (1), forming a closed annular cavity structure; The axial midpoint of the raw material receiving area (2) coincides with the axial midpoint of the crucible body (1).

4. The crucible structure for high-efficiency silicon carbide single crystal growth according to claim 1, characterized in that, The top seed crystal (3) is fixed to the central region of the top inner wall of the crucible body (1); The bottom seed crystal (4) is fixed to the central region of the bottom inner wall of the crucible body (1); The geometric center of the top seed crystal (3) and the geometric center of the bottom seed crystal (4) are both located on the central axis of the crucible body (1).

5. The crucible structure for high-efficiency silicon carbide single crystal growth according to claim 1, characterized in that, The heating assembly (5) includes a side heater (51); The side heater (51) has a cylindrical structure and is fixed around the outside of the side wall of the crucible body (1); The axial coverage of the side heater (51) corresponds to the axial coverage of the raw material receiving area (2).

6. The crucible structure for high-efficiency silicon carbide single crystal growth according to claim 5, characterized in that, The heating assembly (5) also includes a top heater (52) and a bottom heater (53); The top heater (52) is fixedly disposed on the top outer side of the crucible body (1), and the bottom heater (53) is fixedly disposed on the bottom outer side of the crucible body (1). The top heater (52), the side heater (51), and the bottom heater (53) are arranged independently of each other.

7. The crucible structure for high-efficiency silicon carbide single crystal growth according to claim 1, characterized in that, The heating component (5) is a spiral induction coil, which is coaxially wrapped around the outer periphery of the crucible body (1); The coil turn pitch in the axial middle section of the spiral induction coil is smaller than the coil turn pitch in the axial end sections.

8. The crucible structure for high-efficiency silicon carbide single crystal growth according to claim 1, characterized in that, The heating component (5) is a circumferentially continuous integral cylindrical structure with no splicing breaks or assembly gaps in the circumferential direction.

9. The crucible structure for high-efficiency silicon carbide single crystal growth according to claim 1, characterized in that, The crucible body (1) is an axisymmetric cylindrical closed structure with closed ends at the top and bottom, forming an independent growth chamber inside.

10. The crucible structure for high-efficiency silicon carbide single crystal growth according to claim 2, characterized in that, The center of the porous filter plate (6) is coaxially arranged with the center of the bottom seed crystal (4), and the surface of the porous filter plate (6) covers the entire crystal surface area of ​​the bottom seed crystal (4).

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