A PVT furnace partition heating holding device

Abstract

The utility model relates to a kind of PVT furnace partition heating heat preservation devices, including main part. Main body includes the top plate of vertical upper end setting and the bottom plate of vertical lower end setting. Top plate and bottom plate are provided with, side wall. The internal space formed by top plate, bottom plate and side wall is provided with crucible. The vertical upper end of crucible is provided with eight inch silicon carbide seed crystal. The vertical lower end of crucible is provided with silicon carbide powder source area. The vertical lower end of crucible is also provided with variable distance heating assembly. Heating assembly includes several heating pieces and guide rail. Several heating pieces and corresponding guide rail rectangular array distribution, and several heating pieces are equidistantly moved along guide rail towards the direction of long or wide in rectangular array. The utility model can adjust heating piece arrangement pertinently in the corresponding thickness stage of crystal growth, can continuously maintain heat field in optimal state, fundamentally solve the problem of crystal defect caused by uneven heat field, significantly improve eight inch silicon carbide seed crystal, the quality of the grown silicon carbide single crystal.

Description

Technical Field

[0001] This utility model relates to the field of silicon carbide single crystal preparation technology, and in particular to a PVT furnace zoned heating and heat preservation device. Background Technology

[0002] Physical vapor transport (PVT) is one of the most mainstream technologies for preparing high-quality silicon carbide single crystals. Its core principle involves heating the silicon carbide raw material at high temperatures using a heating device, causing it to decompose into gaseous compounds such as Si, Si₂C, and SiC₂. These gaseous compounds are then transported towards the cooler seed crystal under the influence of a temperature gradient, recrystallizing on the seed crystal surface to grow into silicon carbide single crystals. During this process, the uniformity of the thermal field distribution, the stability of the heat preservation performance, and the controllability of the gas phase environment within the PVT furnace directly determine the growth rate, crystal quality (such as defect density and uniformity), and preparation cost of the silicon carbide single crystal, making them key factors affecting industrial production efficiency. In particular, 8-inch silicon carbide (SiC) single crystals, due to their larger chip fabrication area, lower unit cost, and better performance compatibility, have become the core development direction for the industrialization of third-generation semiconductor materials. Physical vapor transport (PVT) remains the mainstream technology for 8-inch SiC single crystal preparation due to its high process maturity and easy control of single crystal purity. As the core energy supply unit of the PVT growth furnace, the induction heating system directly determines the dislocation density, thickness uniformity, and growth efficiency of 8-inch SiC single crystals through its heating uniformity, dynamic control precision, and heat preservation coordination. This is a key technological breakthrough for the "8-inch SiC single crystal PVT growth furnace induction heating system".

[0003] Existing PVT furnace heating and insulation devices mostly employ integral heating or fixed-zone heating structures. These structures have gradually revealed numerous technical shortcomings in practical applications. Regarding thermal field control, the heating elements in traditional heating components are often fixed in position, making it impossible to flexibly adjust them according to thickness variations and thermal field requirements at different crystal growth stages. Since the optimal thermal field parameters for different thicknesses differ significantly during silicon carbide single crystal growth, fixed heating structures struggle to maintain the optimal thermal field throughout the entire growth process. This often leads to temperature fluctuations at the crystal growth interface, resulting in crystal defects such as dislocations and inclusions. This thermal field inhomogeneity is particularly pronounced in the preparation of large-size silicon carbide single crystals, such as eight-inch crystals, severely hindering quality improvement. Furthermore, the design of the gaseous compound flow channels inside the crucible is often inadequate, relying heavily on natural convection for gas transport. This results in low gas flow efficiency and uneven distribution, making it difficult to form a stable concentration gradient. This not only limits the single crystal growth rate but may also lead to uneven crystal composition due to localized accumulation of gaseous compounds.

[0004] To address the aforementioned issues, there is an urgent need to develop a PVT furnace heating and insulation device with precise thermal field control capabilities, excellent thermal insulation performance, and an efficient gas phase transport environment. By optimizing the heating component structure, improving the thermal insulation and sealing design, and the gas phase flow channel, the optimal thermal field can be maintained throughout the crystal growth process, thereby improving the quality and growth efficiency of single crystals and meeting the needs of industrialized production of 8-inch silicon carbide single crystals.

[0005] Furthermore, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the applicant studied a large number of documents and patents when making this utility model, but due to space limitations, not all details and contents were listed in detail. However, this does not mean that this utility model does not have the features of these prior art. On the contrary, this utility model has all the features of the prior art, and the applicant reserves the right to add relevant prior art to the background art. Utility Model Content

[0006] To address the shortcomings of existing technologies, this utility model provides a PVT furnace zoned heating and insulation device, comprising a main body. The main body includes a top plate vertically positioned at its upper end and a bottom plate vertically positioned at its lower end. A side wall for insulation is provided between the top plate and the bottom plate. A crucible is disposed within the internal space formed by the top plate, the bottom plate, and the side wall. An eight-inch silicon carbide seed crystal is disposed at the vertical upper end of the crucible. A silicon carbide powder source area is disposed at the vertical lower end of the crucible. A variable-pitch heating assembly is also disposed at the vertical lower end of the crucible. The heating assembly includes several heating elements and guide rails for the heating elements connected in series. The several heating elements and corresponding guide rails are distributed in a rectangular array, and the several heating elements move at equal intervals along the guide rails in the length or width direction of the rectangular array.

[0007] According to a preferred embodiment, the number of heating elements on each guide rail is odd and greater than or equal to three. The heating element located in the middle of the guide rail serves as a fixed base and is connected to several heating elements via connectors.

[0008] According to a preferred embodiment, a plurality of connectors are disposed between adjacent heating elements. The connectors are configured as parallelogram linkage mechanisms. At least two endpoints of the connectors are respectively disposed on at least two adjacent heating elements to connect the heating elements at equal intervals via the connectors.

[0009] According to a preferred embodiment, at least one heating element located at the edge of the guide rail is fixedly connected to the output end of the cylinder. The cylinder is fixed to the end of the guide rail away from the heating element.

[0010] According to a preferred embodiment, a guide rail passes through a plurality of heating elements and is slidably and / or fixedly connected to the plurality of heating elements. The guide rail is fixedly connected to the plurality of heating elements that serve as fixed bases, and slidably connected to the plurality of heating elements that do not serve as fixed bases.

[0011] According to a preferred embodiment, a side heater surrounding the crucible is also provided within the main body. The side heater is fixedly connected to the top plate and / or bottom plate by bolts.

[0012] According to a preferred embodiment, the crucible is provided with a plurality of pores. The plurality of pores are respectively located at the upper vertical end and the lower vertical end of the crucible, and are correspondingly arranged in the vertical direction.

[0013] According to a preferred embodiment, a buffer chamber is provided vertically below the crucible. A vent extends through the buffer chamber to the bottom plate.

[0014] According to a preferred embodiment, an air passage is provided between at least two vertically corresponding air holes. The air passage extends sequentially along the top plate, side wall, bottom plate, buffer cavity, and crucible to connect at least two air holes.

[0015] According to a preferred embodiment, the top plate and bottom plate have inner recessed sidewalls to cover the edges of the annularly arranged sidewalls. Attached Figure Description

[0016] Figure 1 This is a simplified structural diagram of a PVT furnace zoned heating and insulation device according to a preferred embodiment of the present invention.

[0017] Figure 2 This is a simplified structural diagram of the shrinking heating component after being cut open in a preferred embodiment of the PVT furnace partition heating and insulation device provided by this utility model.

[0018] Figure 3 This is a simplified structural diagram of the heating components unfolded after being cut open, according to a preferred embodiment of the PVT furnace zoned heating and insulation device provided by this utility model.

[0019] List of reference numerals

[0020] 100: Main body; 101: Top plate; 102: Bottom plate; 103: Side wall; 104: Crucible; 105: Eight-inch silicon carbide seed crystal; 106: Silicon carbide powder source area; 107: Pores; 108: Buffer cavity; 109: Air passage; 200: Heating assembly; 201: Heating element; 202: Guide rail; 203: Connector; 204: Cylinder; 205: Side heater. Detailed Implementation

[0021] The following is a detailed explanation with reference to the accompanying drawings.

[0022] Example 1

[0023] This utility model provides a zoned heating and heat preservation device for a PVT furnace, such as... Figure 1As shown, the system includes a main body 100. The main body 100 includes a top plate 101 vertically positioned at its upper end and a bottom plate 102 vertically positioned at its lower end. A side wall 103 for heat insulation is provided between the top plate 101 and the bottom plate 102. A crucible 104 is disposed within the internal space formed by the top plate 101, the bottom plate 102, and the side wall 103. An eight-inch silicon carbide seed crystal 105 is disposed at the vertical upper end of the crucible 104. A silicon carbide powder source region 106 is disposed at the vertical lower end of the crucible 104. A variable-pitch heating assembly 200 is also disposed at the vertical lower end of the crucible 104. The heating assembly 200 includes a plurality of heating elements 201 and guide rails 202 for the series heating elements 201. The plurality of heating elements 201 and corresponding guide rails 202 are arranged in a rectangular array, and the plurality of heating elements 201 move at equal intervals along the guide rails 202 in the length or width direction of the rectangular array. The free movement of the heating element 201 facilitates the adjustment of the thermal field at the bottom of the crucible 104. Through prior simulation calculations of the single crystal, it was determined that the density of the heating element 201 should be adjusted at the corresponding thickness of the crystal to maintain it within the optimal thermal field, thereby improving the quality of the single crystal. The overall structure of this device provides a stable heat preservation foundation and flexible thermal field control capability for single crystal growth in a PVT furnace. The enclosed space formed by the top plate 101, bottom plate 102, and side wall 103 effectively reduces heat loss, creating a growth environment with excellent heat preservation performance for the crucible 104 and reducing energy consumption. The variable-pitch heating assembly 200, through the free movement of the heating element 201 along the guide rail 202, breaks the limitation of the fixed thermal field in traditional heating devices, achieving precise adjustment of the thermal field at the bottom of the crucible 104. Based on the results of single-crystal simulation calculations, the density of the heating element 201 can be adjusted in a targeted manner at the corresponding thickness stage of crystal growth, which can maintain the thermal field in an optimal state. This fundamentally solves the crystal defect problem caused by uneven thermal field and significantly improves the quality of silicon carbide single crystals grown by the eight-inch silicon carbide seed crystal 105. At the same time, the flexible thermal field adjustment capability also makes it possible to adapt to different growth requirements and enhances the versatility of the device.

[0024] According to a preferred embodiment, such as Figure 2 and Figure 3As shown, the number of heating elements 201 on each guide rail 202 is odd and greater than or equal to three. The heating element 201 located in the middle of the guide rail 202 serves as a fixed base and is connected to several heating elements 201 via connectors 203. The odd number design results in a symmetrical distribution of the heating elements 201. The adjustment method based on the middle element ensures the symmetry and stability of the thermal field changes, avoiding local thermal field shifts during adjustment. The middle heating element 201, as a fixed base, provides a stable support foundation for the entire heating assembly 200, preventing overall displacement of the heating elements 201 during movement or operation, and ensuring the accuracy of thermal field adjustment. Connectors 203 connect the heating elements 201 into an organic whole, enabling the synchronous transmission of adjustment actions of individual heating elements 201, achieving equidistant adjustment of the spacing between the heating elements 201, further improving the uniformity of the thermal field distribution, and providing a more stable temperature environment for crystal growth.

[0025] According to a preferred embodiment, a plurality of connecting members 203 are disposed between adjacent heating elements 201. The connecting members 203 are configured as parallelogram linkage mechanisms. At least two endpoints of the connecting members 203 are respectively disposed on at least two adjacent heating elements 201 to connect the heating elements 201 at equal intervals via the connecting members 203. The connecting members 203, configured as parallelogram linkage mechanisms, have the characteristics of smooth movement and precise transmission, and can uniformly transmit the displacement of a single heating element 201 to all connected heating elements 201, ensuring that the spacing between each heating element 201 remains consistent during adjustment, avoiding local temperature fluctuations caused by uneven spacing. This equidistant connection method achieved through the connecting members 203 simplifies the thermal field adjustment operation, eliminating the need for individual control of each heating element 201; uniform change of the overall thermal field can be achieved by controlling only a portion of the heating elements 201, improving operational efficiency. Simultaneously, the structural stability of the connecting members 203, configured as linkage mechanisms, also enhances the overall rigidity of the heating assembly 200, reducing the impact of mechanism deformation on the accuracy of thermal field adjustment under high-temperature environments.

[0026] According to a preferred embodiment, at least one heating element 201 located at the edge of the guide rail 202 is fixedly connected to the output end of a cylinder 204. The cylinder 204 is fixed at the end of the guide rail 202 away from the heating element 201. The heating element 201 at the edge of the guide rail 202 is fixed to the output end of the cylinder 204, and the cylinder 204 can be controlled by various control modules. This design provides a stable and flexible power source and control method for the heating assembly 200. The cylinder 204 drive has the characteristics of smooth power output and rapid response, and can accurately control the movement distance of the heating element 201, ensuring that the accuracy of the thermal field adjustment meets the requirements of crystal growth.

[0027] It should be noted that the cylinder 204 of this application can be controlled by any Bluetooth module, wired control or other control module, and synchronous action can be achieved by connecting control modules in parallel or asynchronous action can be achieved by controlling modules independently. This control method is a conventional technical means and will not be described in detail here.

[0028] According to a preferred embodiment, a guide rail 202 passes through a plurality of heating elements 201 and is slidably and / or fixedly connected to the plurality of heating elements 201. The guide rail 202 is fixedly connected to a plurality of heating elements 201 that serve as fixed bases, and slidably connected to a plurality of heating elements 201 that do not serve as fixed bases. The guide rail 202 and the heating elements 201 adopt a composite connection method of "fixed + sliding," balancing the structural stability and adjustment flexibility of the heating assembly 200. The fixed connection between the guide rail 202 and the intermediate heating element 201 that serves as a fixed base further strengthens the support strength of the entire heating assembly 200, ensuring that the guide rail 202 and the heating elements 201 will not undergo relative displacement under high-temperature operating conditions, providing structural protection for thermal field stability. The slidable connection between the guide rail 202 and the heating elements 201 that do not serve as fixed bases allows these heating elements 201 to move smoothly along the guide rail 202, reducing frictional resistance during adjustment and improving the convenience and accuracy of thermal field adjustment. This differentiated connection method not only avoids the overall structure from becoming loose and affecting the accuracy of the thermal field, but also ensures the flexibility of adjusting the heating element 201, making the thermal field control more reliable and efficient.

[0029] According to a preferred embodiment, a side heater 205 surrounding the crucible 104 is also provided inside the main body 100. The side heater 205 is fixedly connected to the top plate 101 and / or the bottom plate 102 by bolts. The side heater 205 surrounding the crucible 104 inside the main body 100 and fixed to the top plate 101 or the bottom plate 102 by bolts forms a three-dimensional heating mode of "bottom + side", which significantly optimizes the thermal field distribution of the crucible 104. The side heater 205 can uniformly heat the side wall of the crucible 104, making up for the problem of uneven temperature between the top and bottom of the crucible 104 that may be caused by heating only the bottom heating component 200, so that the overall temperature gradient of the crucible 104 is more reasonable and meets the requirements of crystal growth for a full-range temperature environment. The bolt fixing method has the characteristics of firm connection and convenient disassembly and assembly, which not only ensures the installation stability of the side heater 205 in the high-temperature working environment, but also facilitates the later maintenance, replacement or adjustment of the position of the side heater 205, reducing equipment maintenance costs. The formation of a three-dimensional heating mode further enhances the controllability of the thermal field, providing a stronger guarantee for improving the quality of single crystals.

[0030] According to a preferred embodiment, a plurality of pores 107 are provided on the crucible 104. The pores are located at the vertical upper end and the vertical lower end of the crucible 104, and are correspondingly arranged in the vertical direction. The pores 107 create favorable conditions for gas flow inside the crucible 104, optimizing the gas phase environment for crystal growth. The vertically and vertically distributed pores 107 form the basic channels for gas convection.

[0031] According to a preferred embodiment, a buffer cavity 108 is provided vertically below the crucible 104. A vent 107 extends through the buffer cavity 108 to the bottom plate 102. The buffer cavity 108 stabilizes and regulates the gas flow inside the crucible 104. The buffer cavity 108 buffers and stabilizes the gas flowing out from the vent 107, preventing sudden pressure changes inside the crucible 104 caused by direct gas discharge, maintaining a stable internal pressure environment, and providing stable pressure conditions for crystal growth.

[0032] According to a preferred embodiment, an air passage 109 is provided between at least two vertically corresponding air holes 107. The air passage 109 extends sequentially along the top plate 101, side wall 103, bottom plate 102, buffer cavity 108, and crucible 104 to connect at least two air holes 107. The through-type design of the air passage 109 allows the air holes 107 at the upper and lower ends of the crucible 104 to form a complete convection loop, ensuring smooth gas flow inside the crucible 104, between the side wall 103 and the buffer cavity 108, and significantly enhancing the gas convection effect. Under the combined action of the bottom heating component 200 and the side heater 205, the gas convection speed is accelerated, causing a large concentration gradient of gaseous compounds such as Si2C, SiC2, and Si generated by the decomposition of silicon carbide powder source region 106 within the crucible 104. The increased concentration gradient can accelerate the diffusion rate of gaseous compounds toward the 105 direction of the eight-inch silicon carbide seed crystal, providing a more sufficient source of material for crystal growth, thereby effectively improving the growth rate of single crystals, shortening the production cycle, and increasing production efficiency.

[0033] According to a preferred embodiment, the top plate 101 and bottom plate 102 are inwardly fitted with sidewalls 103 to cover the edges of the annularly arranged sidewalls 103. The interior of the sidewalls 103 can be filled with insulating material. This structural design significantly improves the overall insulation performance of the device and reduces energy loss. The inwardly fitted structure of the top plate 101 and bottom plate 102 increases the contact area with the sidewalls 103, reducing heat loss at the connection points and creating a more tightly sealed, insulated space. The design of filling the sidewalls 103 with insulating material further enhances their thermal insulation capabilities, effectively preventing heat transfer from the furnace to the outside, maintaining a stable furnace temperature environment, reducing frequent operation of the heating components 200 due to heat loss, and lowering energy consumption. The excellent insulation performance makes the furnace thermal field more stable, avoiding the impact of external environmental temperature fluctuations on crystal growth, providing a more reliable temperature guarantee for single crystal growth, and also reducing equipment operating costs.

[0034] It should be noted that the specific embodiments described above are exemplary. Those skilled in the art can devise various solutions inspired by the disclosure of this utility model, and these solutions all fall within the scope of this utility model and its protection scope. Those skilled in the art should understand that this utility model specification and its drawings are illustrative and do not constitute a limitation on the claims. The protection scope of this utility model is defined by the claims and their equivalents. This utility model specification contains multiple inventive concepts; phrases such as "preferred" or "according to a preferred embodiment" indicate that the corresponding paragraph discloses an independent concept. The applicant reserves the right to file divisional applications based on each inventive concept. Throughout the text, the feature introduced by "preferred" is only an optional mode and should not be construed as mandatory. Therefore, the applicant reserves the right to abandon or delete relevant preferred features at any time.

Claims

1. A zoned heating and insulation device for a PVT furnace, characterized in that, The system includes a main body (100), which comprises a top plate (101) vertically positioned at its upper end and a bottom plate (102) vertically positioned at its lower end. A side wall (103) for heat insulation is provided between the top plate (101) and the bottom plate (102). A crucible (104) is disposed in the internal space formed by the top plate (101), the bottom plate (102), and the side wall (103). An eight-inch silicon carbide seed crystal (105) is disposed at the upper end of the crucible (104), and a silicon carbide powder source region (106) is disposed at the lower end of the crucible (104). The crucible (104) is also provided with a variable-pitch heating component (200) at its vertical lower end. The heating component (200) includes a plurality of heating elements (201) and a guide rail (202) that connects the heating elements (201) in series. The plurality of heating elements (201) and the corresponding guide rail (202) are distributed in a rectangular array, and the plurality of heating elements (201) move at equal distances along the guide rail (202) toward the length or width of the rectangular array.

2. The PVT furnace zoned heating and insulation device according to claim 1, characterized in that, The number of heating elements (201) on each guide rail (202) is odd and greater than or equal to three. The heating element (201) located in the middle position of the guide rail (202) serves as a fixed base and is connected to several heating elements (201) through a connector (203).

3. The PVT furnace zoned heating and insulation device according to claim 2, characterized in that, Several of the connecting members (203) are disposed between adjacent heating members (201), wherein, The connector (203) is configured as a parallelogram linkage mechanism, and at least two endpoints of the connector (203) are respectively disposed on at least two adjacent heating elements (201) to connect the heating elements (201) at equal intervals through the connectors (203).

4. The PVT furnace zoned heating and insulation device according to claim 3, characterized in that, At least one of the heating elements (201) located at the edge of the guide rail (202) is fixedly connected to the output end of the cylinder (204), wherein, The cylinder (204) is fixed to the end of the guide rail (202) away from the heating element (201).

5. The PVT furnace zoned heating and insulation device according to claim 4, characterized in that, The guide rail (202) passes through a plurality of the heating elements (201) and is slidably connected and / or fixedly connected to the plurality of the heating elements (201), wherein, The guide rail (202) is fixedly connected to a plurality of heating elements (201) that serve as fixed bases, and is slidably connected to a plurality of heating elements (201) that do not serve as fixed bases.

6. The PVT furnace zoned heating and insulation device according to claim 5, characterized in that, The main body (100) is also provided with a side heater (205) surrounding the crucible (104), and the side heater (205) is fixedly connected to the top plate (101) and / or the bottom plate (102) by bolts.

7. The PVT furnace zoned heating and insulation device according to claim 6, characterized in that, The crucible (104) is provided with a plurality of air holes (107), which are located at the upper vertical end and the lower vertical end of the crucible (104) respectively, and are arranged correspondingly in the vertical direction.

8. The PVT furnace zoned heating and insulation device according to claim 7, characterized in that, A buffer chamber (108) is provided vertically below the crucible (104), and the vent (107) extends through the buffer chamber (108) to the bottom plate (102).

9. The PVT furnace zoned heating and insulation device according to claim 8, characterized in that, An air passage (109) is provided between at least two vertically corresponding air holes (107). The air passage (109) extends sequentially along the top plate (101), the side wall (103), the bottom plate (102), the buffer cavity (108), and the crucible (104) to connect at least two of the air holes (107).

10. The PVT furnace zoned heating and insulation device according to claim 9, characterized in that, The top plate (101) and the bottom plate (102) are recessed into the side wall (103) to cover the edge of the circumferentially arranged side wall (103).

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