Single crystal furnace and method for manufacturing single crystal furnace

Abstract

The application relates to a single crystal furnace and a preparation method thereof. The single crystal furnace comprises a furnace bottom, a furnace cylinder and a furnace cover. The furnace bottom is fixedly connected with the furnace cylinder, and the furnace cover is detachably connected with one side of the furnace cylinder away from the furnace bottom. When the furnace cover is connected with the furnace cylinder, the furnace bottom, the furnace cylinder and the furnace cover can jointly form a heating cavity. The inner walls of the furnace bottom, the furnace cylinder and the furnace cover close to the heating cavity are all coated with heat preservation materials. When single crystal silicon is processed through the single crystal furnace, the inner walls of the furnace bottom, the furnace cylinder and the furnace cover close to the heating cavity are all coated with heat preservation materials, so that the heat exchange speed between the internal heat system in the furnace body and the furnace wall can be effectively reduced in the process of the single crystal silicon crystallization growth, the heat loss in the whole preparation process is effectively reduced, the energy consumption cost of the single crystal silicon in the preparation process is low, the manufacturing cost of the single crystal silicon is reduced, the manufacturing cost of the whole solar cell is low, and the solar cell is conducive to popularization.

Description

Technical Field

[0001] This application relates to the field of single-crystal silicon preparation technology, and in particular to single-crystal furnaces and methods for preparing single-crystal furnaces. Background Technology

[0002] With the development of modern industry, the global energy crisis and air pollution problems are becoming increasingly prominent, and traditional fuel energy is dwindling day by day. Since abundant solar radiation is an important renewable energy source, solar cells, with their ability to convert solar radiation into electricity, have become a focus of attention. Monocrystalline silicon, as a crucial material for manufacturing solar cells, directly impacts the profit margin and energy costs of the entire industry. However, in current technologies, the manufacturing cost of monocrystalline silicon is relatively high, leading to a higher overall manufacturing cost for solar cells, which hinders their rapid adoption. Summary of the Invention

[0003] Therefore, it is necessary to provide a single-crystal furnace to address the problem that the manufacturing cost of existing monocrystalline silicon is high, which in turn leads to the high manufacturing cost of the entire solar cell.

[0004] A single crystal furnace includes a furnace bottom, a furnace cylinder, and a furnace cover; the furnace bottom is fixedly connected to the furnace cylinder, and the furnace cover is detachably connected to the side of the furnace cylinder away from the furnace bottom.

[0005] When the furnace cover is connected to the furnace cylinder, the furnace bottom, the furnace cylinder, and the furnace cover can together form a heating chamber; the inner walls of the furnace bottom, the furnace cylinder, and the furnace cover near the heating chamber are all coated with heat-insulating material.

[0006] In one embodiment, the insulation material has a multi-layer structure, and the insulation material is at least one of barrier insulation coating, reflective insulation coating, and radiative insulation coating.

[0007] In one embodiment, the thickness h of the insulation material satisfies the following condition:

[0008] 10mm≤h≤20mm.

[0009] In one embodiment, the thermal insulation material coated on the inner wall of the furnace bottom includes the reflective thermal insulation coating, the radiative thermal insulation coating, and the barrier thermal insulation coating; the thickness of the reflective thermal insulation coating coated on the inner wall of the furnace bottom is a first thickness h1, the thickness of the radiative thermal insulation coating coated on the inner wall of the furnace bottom is a second thickness h2, and the thickness of the barrier thermal insulation coating coated on the inner wall of the furnace bottom is a third thickness h3.

[0010] Wherein, the first thickness h1 is less than the second thickness h2, and the second thickness h2 is less than the third thickness h3.

[0011] In one embodiment, the thermal insulation material coated on the inner wall of the furnace cylinder includes the reflective thermal insulation coating, the radiative thermal insulation coating, and the barrier thermal insulation coating; the thickness of the reflective thermal insulation coating coated on the inner wall of the furnace cylinder is a fourth thickness h4, the thickness of the radiative thermal insulation coating coated on the inner wall of the furnace cylinder is a fifth thickness h5, and the thickness of the barrier thermal insulation coating coated on the inner wall of the furnace cylinder is a sixth thickness h6.

[0012] Wherein, the fourth thickness h4 and the sixth thickness h6 are both greater than the fifth thickness h5, and the values ​​of the fourth thickness h4 and the sixth thickness h6 are the same or different.

[0013] In one embodiment, the thermal insulation material coated on the inner wall of the furnace cover includes the reflective thermal insulation coating, the radiative thermal insulation coating, and the barrier thermal insulation coating; the thickness of the reflective thermal insulation coating coated on the inner wall of the furnace cover is a seventh thickness h7, the thickness of the radiative thermal insulation coating coated on the inner wall of the furnace cover is an eighth thickness h8, and the thickness of the barrier thermal insulation coating coated on the inner wall of the furnace cover is a ninth thickness h9.

[0014] Wherein, the eighth thickness h8 and the ninth thickness h9 are both less than the seventh thickness h7, and the values ​​of the eighth thickness h8 and the ninth thickness h9 are the same or different.

[0015] This application also provides a method for preparing a single crystal furnace, comprising:

[0016] Clean the walls of the heating chamber of the single crystal furnace;

[0017] Thermal insulation material is coated on the inner walls of the furnace cover, furnace cylinder, and furnace bottom near the heating chamber of the single crystal furnace;

[0018] The single crystal furnace is vacuum-calcined at a preset power for a preset duration.

[0019] In one embodiment, the step of coating the inner walls of the furnace cover, furnace cylinder, and furnace bottom near the heating chamber with heat-insulating material, and vacuum calcining the single crystal furnace at a preset power for a preset time specifically includes:

[0020] The inner walls of the furnace cover, furnace cylinder, and furnace bottom near the heating chamber of the single crystal furnace are coated with a first heat-insulating coating and left to stand.

[0021] The single crystal furnace is vacuum-calcined at a first preset power for a first preset duration;

[0022] The first thermal insulation coating is one of a reflective thermal insulation coating, a radiative thermal insulation coating, and a barrier thermal insulation coating.

[0023] In one embodiment, after the step of vacuum calcining the single crystal furnace with a first preset power for a first preset time, the method further includes:

[0024] A second heat-insulating coating is applied to the furnace cover, furnace cylinder, and furnace bottom plate of the single crystal furnace and left to stand.

[0025] The single crystal furnace is vacuum-calcined at a second preset power for a second preset duration;

[0026] The second thermal insulation coating is different from the first thermal insulation coating. The second thermal insulation coating is one of reflective thermal insulation coating, radiative thermal insulation coating, and barrier thermal insulation coating.

[0027] In one embodiment, after the step of vacuum calcining the single crystal furnace with a second preset power for a second preset time, the method further includes:

[0028] A third heat-insulating coating is sprayed onto the furnace cover, furnace cylinder, and furnace bottom of the single crystal furnace and left to stand.

[0029] The single crystal furnace is vacuum-calcined at a third preset power for a third preset duration;

[0030] The third thermal insulation coating is different from both the first and second thermal insulation coatings. The third thermal insulation coating is one of the following: reflective thermal insulation coating, radiative thermal insulation coating, and barrier thermal insulation coating.

[0031] In one embodiment, the thickness of the reflective heat-insulating coating applied to the inner wall of the furnace bottom is the first thickness h1, the thickness of the radiative heat-insulating coating applied to the inner wall of the furnace bottom is the second thickness h2, and the thickness of the barrier heat-insulating coating applied to the inner wall of the furnace bottom is the third thickness h3.

[0032] Wherein, the first thickness h1 is less than the second thickness h2, and the second thickness h2 is less than the third thickness h3.

[0033] In one embodiment, the thickness of the reflective heat-insulating coating applied to the inner wall of the furnace cylinder is a fourth thickness h4, the thickness of the radiative heat-insulating coating applied to the inner wall of the furnace cylinder is a fifth thickness h5, and the thickness of the barrier heat-insulating coating applied to the inner wall of the furnace cylinder is a sixth thickness h6.

[0034] Wherein, the fourth thickness h4 and the sixth thickness h6 are both greater than the fifth thickness h5, and the values ​​of the fourth thickness h4 and the sixth thickness h6 are the same or different.

[0035] In one embodiment, the thickness of the reflective heat-insulating coating applied to the inner wall of the furnace cover is a seventh thickness h7, the thickness of the radiative heat-insulating coating applied to the inner wall of the furnace cover is an eighth thickness h8, and the thickness of the barrier heat-insulating coating applied to the inner wall of the furnace cover is a ninth thickness h9.

[0036] Wherein, the eighth thickness h8 and the ninth thickness h9 are both less than the seventh thickness h7, and the values ​​of the eighth thickness h8 and the ninth thickness h9 are the same or different.

[0037] When monocrystalline silicon is processed using the monocrystalline furnace prepared by the above-mentioned method, the monocrystalline silicon crystallizes and grows in the heating chamber. Since the inner walls of the furnace bottom, furnace cylinder, and furnace cover near the heating chamber are all coated with heat-insulating material, the heat exchange rate between the internal heat system and the furnace wall can be effectively reduced during the monocrystalline silicon crystallization and growth process. This effectively reduces the heat loss in the entire preparation process, resulting in lower energy consumption costs during the preparation of monocrystalline silicon. This reduces the manufacturing cost of monocrystalline silicon and consequently lowers the overall manufacturing cost of solar cells, which is more conducive to the rapid promotion of solar cells. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of a single crystal furnace provided in an embodiment of this application.

[0039] Figure 2 for Figure 1 The diagram shows the internal structure of a single crystal furnace.

[0040] Figure 3 This is a schematic diagram illustrating a method for manufacturing a single crystal furnace according to an embodiment of this application.

[0041] Reference numerals: 110-furnace bottom; 120-furnace cylinder; 130-furnace cover; 140-internal hot zone graphite components. Detailed Implementation

[0042] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0043] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not 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 application.

[0044] Furthermore, where the terms "first" and "second" appear, these terms are 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 with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0045] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," 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 or an electrical 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, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0046] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via 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. Similarly, "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.

[0047] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0048] With the increasing variety of solar cells, their expanding applications, and the growing market size, monocrystalline silicon-based cells have become the dominant force in the solar power generation market due to their stable conversion efficiency, long lifespan, and low cost. As a crucial material for manufacturing silicon-based cells, the cost of monocrystalline silicon wafers directly impacts the profit margins and energy costs of the entire industry. Therefore, reducing the manufacturing cost of monocrystalline silicon wafers is becoming increasingly important. Currently, the production cost of monocrystalline silicon includes raw material costs, energy consumption costs, equipment costs, and site costs.

[0049] The production of monocrystalline silicon rods, the raw material for monocrystalline silicon wafers, is mainly achieved through the Czochralski process. Specifically, in a cylindrical monocrystalline furnace, polycrystalline silicon in a high-purity quartz crucible is melted using graphite resistance heating. A seed crystal is then inserted into the surface of the melt for fusion. The rotating seed crystal is lowered to wet and contact the melt, and gradually raised. The production process is completed through steps such as necking, necking, shoulder formation, equal diameter control, and finishing.

[0050] The equipment for growing single-crystal silicon rods mainly consists of six parts: single-crystal furnace, electrical components, thermal system, water cooling system, vacuum system, and argon gas supply device. Its heating system mainly consists of a graphite heater, a heat shield (the heat shield is composed of an outer liner, an inner liner, intermediate insulation filling material, upper insulation and cover plate, etc.), a water-cooled heat shield, various supporting graphite components and insulation materials, etc., forming a complete set of internal thermal field graphite components.

[0051] Currently, the heat loss in the Czochralski process for producing monocrystalline silicon mainly includes: (1) the vacuum pump drawing away argon gas during the vacuum system maintenance process, which carries away a portion of the heat; (2) the water-cooled heat shield inside the furnace body, which carries away a portion of the heat to accelerate crystal growth; (3) the crystal rod itself carrying away a portion of the heat after the monocrystalline silicon crystal crystallizes; and (4) the circulating water protecting the monocrystalline furnace body carrying away a portion of the heat. This invention aims to provide a monocrystalline furnace without reducing the heat carried away by the vacuum pump drawing away argon gas during the vacuum system maintenance process; without reducing the heat carried away by the water-cooled heat shield inside the furnace body, which accelerates crystal growth; and without reducing the heat carried away by the crystal rod itself after the monocrystalline silicon crystal crystallizes.

[0052] Please see Figure 1 , Figure 1A schematic diagram of a single crystal furnace provided in one embodiment of this application is shown. The single crystal furnace provided in one embodiment of this application includes a furnace bottom 110, a furnace cylinder 120, and a furnace cover 130; the furnace bottom 110 is fixedly connected to the furnace cylinder 120, and the furnace cover 130 is detachably connected to the side of the furnace cylinder 120 away from the furnace bottom 110; when the furnace cover 130 is connected to the furnace cylinder 120, the furnace bottom 110, the furnace cylinder 120, and the furnace cover 130 can together form a heating chamber; the inner walls of the furnace bottom 110, the furnace cylinder 120, and the furnace cover 130 near the heating chamber are all coated with heat-insulating material.

[0053] When monocrystalline silicon is processed in the aforementioned monocrystalline furnace, during the crystal growth of monocrystalline silicon within the heating chamber, the inner walls of the furnace bottom 110, furnace cylinder 120, and furnace cover 130 near the heating chamber are all coated with heat-insulating material. Therefore, during the monocrystalline silicon crystal growth process, the heat exchange rate between the internal heat system and the furnace wall can be effectively reduced, thereby effectively reducing the heat loss in the entire preparation process. This results in lower energy consumption costs during the preparation of monocrystalline silicon, thus reducing the manufacturing cost of monocrystalline silicon and consequently lowering the overall manufacturing cost of solar cells, which is more conducive to the rapid promotion of solar cells.

[0054] It should be noted that the single crystal furnace in this application has good thermal insulation performance by coating the inner walls of the furnace bottom 110, furnace cylinder 120 and furnace cover 130 near the heating chamber with heat-insulating material. The heat insulation and heat preservation efficiency reaches more than 70%, which makes the thermal field inside the furnace uniform and stable. At the same time, it reduces the power of single crystal silicon growth, reducing the crystal pulling power of single crystal silicon production from the original 64 kW to 57 kW, a reduction of 7 kW, and the energy saving efficiency reaches more than 15%, effectively saving heat loss in the entire preparation process.

[0055] In one specific embodiment, the single crystal furnace is a Czochralski furnace. The Czochralski furnace has a regular and symmetrical structure and a simple surface, which makes it relatively easy to coat the inner wall of the heating chamber with insulation material.

[0056] The following is a detailed description of the structure of the single-crystal furnace. In one embodiment, the insulation material has a multi-layer structure, and the insulation material is at least one of a barrier-type heat-insulating coating, a reflective heat-insulating coating, and a radiative heat-insulating coating. By setting the insulation material to at least one of a barrier-type heat-insulating coating, a reflective heat-insulating coating, and a radiative heat-insulating coating, the overall heat insulation performance of the heating cavity is improved, effectively saving heat loss during the entire preparation process of single-crystal silicon.

[0057] It should be noted that barrier-type thermal insulation coatings are generally made by mixing spherical hollow ceramic microspheres with a particle size of 5-12μm with strong infrared shielding materials to obtain a high-performance, high-quality thermal insulation coating with good temperature resistance. This coating can effectively suppress various conductive and radiative heat, with a thermal insulation suppression efficiency of over 90%. It can suppress the heat radiation and heat conduction loss of both high-temperature and low-temperature objects. When an 8mm thick layer of this high-temperature resistant thermal insulation coating is applied to the surface of an object at 1100℃, the surface temperature can be reduced from 1100℃ to below 100℃, demonstrating excellent energy saving, stability, and improved thermal energy utilization.

[0058] Reflective thermal insulation coatings utilize the principle of reflecting infrared radiation and inhibiting heat conduction for thermal insulation. The thermal reflectivity of these coatings can reach over 80%. After curing, the coating has a specific gravity of only 0.5 g / ml, making it a new type of space-age energy-saving reflective thermal insulation coating that integrates high-efficiency energy saving in a thin layer, thermal insulation, and electrical insulation.

[0059] Radiation-resistant thermal insulation coatings utilize the strong thermal radiation after heat absorption to enhance heat exchange. Also known as high-temperature resistant far-infrared radiation coatings, these coatings are special functional energy-saving coatings with high temperature resistance, strong emissivity, corrosion resistance, and high wear resistance. Through infrared radiation from the coating layer, they improve heat exchange conditions, thereby increasing thermal efficiency, greatly enhancing the thermal efficiency of refractory materials, reducing energy consumption, and saving energy. They also possess excellent physical, chemical, and construction properties.

[0060] In one embodiment, the thickness h of the insulation material satisfies the condition: 10mm ≤ h ≤ 20mm. By setting the thickness of the insulation material within a reasonable range of greater than or equal to 10mm and less than or equal to 20mm, the insulation material is neither too thick nor too thin, thus satisfying the thermal insulation performance of the heating cavity while also achieving good economic benefits.

[0061] In one embodiment, the thickness h of the insulation material is 10 mm. In another embodiment, the thickness h of the insulation material is 20 mm. In yet another embodiment, the thickness h of the insulation material is 15 mm.

[0062] In one embodiment, the insulation material coated on the inner wall of the furnace bottom 110 includes a reflective heat-insulating coating, a radiative heat-insulating coating, and a barrier heat-insulating coating; the thickness of the reflective heat-insulating coating on the inner wall of the furnace bottom 110 is defined as the first thickness h1, the thickness of the radiative heat-insulating coating on the inner wall of the furnace bottom 110 is defined as the second thickness h2, and the thickness of the barrier heat-insulating coating on the inner wall of the furnace bottom 110 is defined as the third thickness h3; wherein, the first thickness h1 is less than the second thickness h2, and the second thickness h2 is less than the third thickness h3.

[0063] By coating the inner wall of the furnace bottom 110 with three types of insulation materials, the furnace bottom 110 achieves good heat insulation performance, thus preventing heat from the heating chamber from dissipating from the furnace bottom 110. Simultaneously, during crystal growth, the furnace bottom 110 is directly subjected to heat conduction from the internal thermal field graphite components 140. The circulating cooling water in the furnace bottom 110, designed to protect the furnace bottom 110 plate, carries away the heat transferred from the growth thermal system to the furnace bottom 110 plate, resulting in energy loss. Therefore, the thickness h3 of the barrier heat insulation coating on the furnace bottom 110 is set to be greater than the thickness h2 of the reflective heat insulation coating and the thickness h1 of the radiative heat insulation coating. This results in a thicker barrier heat insulation coating, effectively reducing the heat exchange rate between the internal thermal field graphite components 140 and the furnace bottom 110, while also effectively reducing the heat carried away by the protective circulating cooling water in the furnace bottom 110, further reducing heat loss.

[0064] In one specific embodiment, the ratio of the first thickness h1 to the second thickness h2 and the third thickness h3 is 2:3:5.

[0065] In another specific embodiment, the ratio of the first thickness h1 to the second thickness h2 and the third thickness h3 is 3:4:5.

[0066] In one embodiment, the insulation material coated on the inner wall of the furnace cylinder 120 includes a reflective heat-insulating coating, a radiative heat-insulating coating, and a barrier heat-insulating coating; the thickness of the reflective heat-insulating coating on the inner wall of the furnace cylinder 120 is defined as the fourth thickness h4, the thickness of the radiative heat-insulating coating on the inner wall of the furnace cylinder 120 is defined as the fifth thickness h5, and the thickness of the barrier heat-insulating coating on the inner wall of the furnace cylinder 120 is defined as the sixth thickness h6; wherein the fourth thickness h4 and the sixth thickness h6 are both greater than the fifth thickness h5, and the values ​​of the fourth thickness h4 and the sixth thickness h6 are the same or different.

[0067] By coating the inner wall of the furnace cylinder 120 with three types of insulation materials, the furnace cylinder 120 achieves good thermal insulation performance, thus preventing heat from the heating chamber from dissipating from the furnace cylinder 120. Simultaneously, during crystal growth, the furnace cylinder 120 is subjected to direct heat radiation from the internal thermal system composed of the graphite components 140 and heat conduction via convection from the internal vacuum gas. The circulating cooling water in the furnace cylinder 120, designed to protect it, carries away the heat transferred from the growth thermal system, resulting in energy loss. Therefore, the thicknesses h4 and h6 of the reflective and barrier thermal insulation coatings on the furnace cylinder 120 are set to be greater than the thickness h5 of the radiative thermal insulation coating. This results in thicker reflective and barrier thermal insulation coatings, effectively reducing the heat exchange rate between the internal thermal system composed of the graphite components 140 and the furnace cylinder 120, while also effectively reducing the heat carried away by the protective circulating water in the furnace cylinder 120, further minimizing heat loss.

[0068] In one specific embodiment, the ratio of the fourth thickness h4 to the fifth thickness h5 and the sixth thickness h6 is 4:2:4.

[0069] In another specific embodiment, the ratio of the fourth thickness h4 to the fifth thickness h5 and the sixth thickness h6 is 4:2:3.

[0070] In another specific embodiment, the ratio of the fourth thickness h4 to the fifth thickness h5 and the sixth thickness h6 is 3:2:4.

[0071] In another specific embodiment, the ratio of the fourth thickness h4 to the fifth thickness h5 and the sixth thickness h6 is 4:3:4.

[0072] In one specific embodiment, the fifth thickness h5 satisfies the condition: 2mm≤h5≤4mm.

[0073] In one embodiment, the insulation material coated on the inner wall of the furnace cover 130 includes a reflective heat-insulating coating, a radiative heat-insulating coating, and a barrier heat-insulating coating; the thickness of the reflective heat-insulating coating on the inner wall of the furnace cover 130 is defined as the seventh thickness h7, the thickness of the radiative heat-insulating coating on the inner wall of the furnace cover 130 is defined as the eighth thickness h8, and the thickness of the barrier heat-insulating coating on the inner wall of the furnace cover 130 is defined as the ninth thickness h9; wherein, the eighth thickness h8 and the ninth thickness h9 are both less than the seventh thickness h7, and the values ​​of the eighth thickness h8 and the ninth thickness h9 are the same or different.

[0074] By coating the inner wall of the furnace cover 130 with three types of insulation materials, the furnace cover 130 exhibits good thermal insulation performance, thus preventing heat from the heating chamber from dissipating from the furnace cover 130. Simultaneously, during crystal growth, the furnace cover 130 is subjected to direct heat radiation from the crystal rod and molten silicon surface. The circulating cooling water in the furnace cover 130 carries away energy transferred from the growth heat system to the furnace cover 130 to protect it, resulting in energy loss. Therefore, the thickness h7 of the reflective thermal insulation coating on the furnace cover 130 is set to be greater than the thickness h8 of the radiation thermal insulation coating and the thickness h9 of the barrier thermal insulation coating. This results in a thicker reflective thermal insulation coating, effectively reducing the heat exchange rate between the internal thermal system composed of the graphite components 140 and the furnace cover 130, while also effectively reducing the heat carried away by the protective circulating water in the furnace cylinder 120, further reducing heat loss.

[0075] In one specific embodiment, the ratio of the seventh thickness h7 to the eighth thickness h8 and the ninth thickness h9 is 4:3:3.

[0076] In another specific embodiment, the ratio of the seventh thickness h7 to the eighth thickness h8 and the ninth thickness h9 is 4:3:2.

[0077] In another specific embodiment, the ratio of the seventh thickness h7 to the eighth thickness h8 and the ninth thickness h9 is 4:2:3.

[0078] In another specific embodiment, the ratio of the seventh thickness h7 to the eighth thickness h8 and the ninth thickness h9 is 4:2:2.

[0079] In one specific embodiment, the seventh thickness h7 satisfies the condition: 4mm≤h7≤8mm.

[0080] It should be noted that the single crystal furnace in this application has different heat transfer methods for the single crystal growth thermal system and different parts of the furnace body (furnace bottom 110, furnace cylinder 120 and furnace cover 130), which results in different thicknesses of the barrier heat insulation coating, reflective heat insulation coating and radiative heat insulation coating applied to the furnace bottom 110, furnace cylinder 120 and furnace cover 130, thereby achieving better heat insulation effect.

[0081] Please see Figure 3 This application also provides a method for preparing a single crystal furnace, which includes:

[0082] S10: Clean the wall of the heating chamber of the single crystal furnace;

[0083] S20: Apply heat-insulating material to the inner walls of the furnace cover 130, furnace cylinder 120 and furnace bottom 110 of the single crystal furnace on the side near the heating chamber;

[0084] S30: Preset duration for vacuum calcination of single crystal furnace with preset power.

[0085] After cleaning the walls of the heating chamber of the single crystal furnace, insulation material is applied to the inner walls of the furnace cover 130, furnace cylinder 120 and furnace bottom 110 near the heating chamber. Finally, the single crystal furnace is vacuum-calcined for a preset time using a preset power to ensure that the insulation material is completely adhered to the inner wall of the heating chamber.

[0086] When a single crystal furnace is prepared using the above-described method, during the processing of single crystal silicon and its crystal growth within the heating chamber, the furnace bottom 110, furnace cylinder 120, and furnace cover 130 are all coated with heat-insulating material on the inner walls near the heating chamber. This effectively reduces the heat exchange rate between the internal thermal system and the furnace wall during the single crystal silicon crystal growth process, thereby significantly reducing heat loss throughout the preparation process. This results in lower energy consumption costs during the preparation of single crystal silicon, thus lowering the manufacturing cost of single crystal silicon and consequently reducing the overall manufacturing cost of solar cells, which is more conducive to the rapid promotion of solar cells.

[0087] In one specific embodiment, the walls of the heating chamber of the single crystal furnace are cleaned with anhydrous ethanol.

[0088] In one embodiment, steps S20 and S30 specifically include: coating the inner wall of the furnace cover 130, furnace cylinder 120 and furnace bottom 110 near the heating chamber of the single crystal furnace with a first heat-insulating coating and letting it stand; vacuum calcining the single crystal furnace with a first preset power for a first preset time; wherein the first heat-insulating coating is one of a reflective heat-insulating coating, a radiative heat-insulating coating and a barrier heat-insulating coating.

[0089] By coating the inner walls of the furnace cover 130, furnace cylinder 120 and furnace bottom 110 near the heating chamber with a first heat-insulating coating and allowing it to stand, the first heat-insulating coating can be surface-dried on the furnace cover 130, furnace cylinder 120 and furnace bottom 110. Then, the single crystal furnace is vacuum-calcined with a first preset power for a first preset time, so that the first heat-insulating coating is completely adhered to the inner wall of the heating chamber.

[0090] In one embodiment, the first thermal insulation coating is a barrier thermal insulation coating.

[0091] In one specific embodiment, when the first insulating coating is a barrier-type heat-insulating coating, the specific process of applying the first insulating coating to the inner wall of the furnace cover 130 near the heating chamber and allowing it to stand is as follows: First, spray a 1mm thick layer of the first insulating coating and wait 10 minutes for it to dry; second, spray a 1mm thick layer of the first insulating coating and wait 10 minutes for it to dry; third, spray a 1mm thick layer of the first insulating coating and wait 10 minutes for it to dry. By applying the first insulating coating to the furnace cover 130 in layers and allowing it to stand, the coating becomes more uniform and the effect is better. Ultimately, the furnace cover 130 is coated with a 3mm thick layer of the first insulating coating.

[0092] Of course, in other embodiments, the thickness of the first insulating coating applied to the inner wall of the furnace cover 130 near the heating chamber can also be 2mm or 4mm, etc., and there is no special limitation on this. It can be done by spraying 1mm each time and allowing it to stand for 10 minutes to dry in layers.

[0093] In one specific embodiment, when the first insulating coating is a barrier-type heat-insulating coating, the specific process of applying the first insulating coating to the inner wall of the furnace cylinder 120 near the heating chamber and allowing it to stand is as follows: First, spray a 1mm thick layer of the first insulating coating and wait 10 minutes for it to dry; second, spray a 1mm thick layer of the first insulating coating and wait 10 minutes for it to dry; third, spray a 1mm thick layer of the first insulating coating and wait 10 minutes for it to dry; fourth, spray a 1mm thick layer of the first insulating coating and wait 10 minutes for it to dry. By applying the first insulating coating to the furnace cylinder 120 in layers and allowing it to stand, the coating becomes more uniform and the effect is better. Ultimately, the furnace cylinder 120 is coated with a 4mm thick layer of the first insulating coating.

[0094] Of course, in other embodiments, the thickness of the first insulating coating applied to the inner wall of the furnace cylinder 120 near the heating chamber can also be 3mm or 5mm, etc., and there is no special limitation on this. It can be done by spraying 1mm each time and allowing it to stand for 10 minutes to dry in layers.

[0095] In one specific embodiment, when the first insulating coating is a barrier-type heat-insulating coating, the specific process of applying the first insulating coating to the inner wall of the furnace bottom 110 near the heating chamber and allowing it to stand is as follows: First, spray a 1mm thick layer of the first insulating coating and wait 10 minutes for it to dry; second, spray a 1mm thick layer of the first insulating coating and wait 10 minutes for it to dry; third, spray a 1mm thick layer of the first insulating coating and wait 10 minutes for it to dry; fourth, spray a 1mm thick layer of the first insulating coating and wait 10 minutes for it to dry; fifth, spray a 1mm thick layer of the first insulating coating and wait 10 minutes for it to dry. By applying the first insulating coating to the furnace bottom 110 in layers and allowing it to stand, the coating becomes more uniform and the effect is better. Ultimately, the furnace bottom 110 is coated with a 5mm thick layer of the first insulating coating.

[0096] Of course, in other embodiments, the thickness of the first insulating coating applied to the inner wall of the furnace bottom 110 near the heating chamber can also be 4mm or 6mm, etc., and there is no special limitation on this. It can be done by spraying 1mm each time and allowing it to stand for 10 minutes to dry in layers.

[0097] In one embodiment, after the step of vacuum calcining the single crystal furnace at a first preset power for a first preset time, the method further includes: coating the furnace cover 130, furnace cylinder 120, and furnace bottom 110 of the single crystal furnace with a second heat-insulating coating and allowing it to stand; and vacuum calcining the single crystal furnace at a second preset power for a second preset time; wherein the second heat-insulating coating is different from the first heat-insulating coating, and the second heat-insulating coating is one of a reflective heat-insulating coating, a radiative heat-insulating coating, and a barrier heat-insulating coating.

[0098] By coating the inner walls of the furnace cover 130, furnace cylinder 120 and furnace bottom 110 near the heating chamber with a second heat-insulating coating and allowing it to stand, the second heat-insulating coating can be surface-dried on the furnace cover 130, furnace cylinder 120 and furnace bottom 110. Then, the single crystal furnace is vacuum-calcined with a second preset power for a second preset time, so that the second heat-insulating coating is completely adhered to the inner wall of the heating chamber.

[0099] In one embodiment, the second thermal insulation coating is a radiation-insulating thermal insulation coating.

[0100] In one specific embodiment, when the second insulating coating is a radiative heat-insulating coating, the specific process for applying the second insulating coating to the inner wall of the furnace cover 130 near the heating chamber and allowing it to stand is as follows: First, spray a 1mm thick layer of the second insulating coating and wait 10 minutes for it to dry completely; second, spray a 1mm thick layer of the second insulating coating and wait 10 minutes for it to dry completely; third, spray a 1mm thick layer of the second insulating coating and wait 10 minutes for it to dry completely. By applying the second insulating coating to the furnace cover 130 in layers and allowing it to stand, the coating becomes more uniform and the effect is better. Ultimately, the furnace cover 130 is coated with a 3mm thick layer of the second insulating coating.

[0101] Of course, in other embodiments, the thickness of the second insulating coating applied to the inner wall of the furnace cover 130 near the heating chamber can also be 2mm or 4mm, etc., and there is no special limitation on this. It can be done by spraying 1mm each time and allowing it to stand for 10 minutes to dry in layers.

[0102] In one specific embodiment, when the second thermal insulation coating is a radiative thermal insulation coating, the specific process for applying the second thermal insulation coating to the inner wall of the furnace cylinder 120 near the heating chamber and allowing it to stand is as follows: First, spray a 1mm thick layer of the second thermal insulation coating and wait 10 minutes for it to dry completely; then spray a second 1mm thick layer of the second thermal insulation coating and wait 10 minutes for it to dry completely. By applying the second thermal insulation coating to the furnace cylinder 120 in layers and allowing it to stand, the coating becomes more uniform and the effect is better. Ultimately, the furnace cylinder 120 is coated with a 2mm thick layer of the second thermal insulation coating.

[0103] Of course, in other embodiments, the thickness of the second insulating coating applied to the inner wall of the furnace cylinder 120 near the heating chamber can also be 1 mm or 3 mm, etc., and there is no special limitation on this. It is acceptable as long as it is applied by spraying 1 mm at a time and allowing it to stand for 10 minutes to dry.

[0104] In one specific embodiment, when the second insulating coating is a radiative heat-insulating coating, the specific process of applying the second insulating coating to the inner wall of the furnace bottom 110 near the heating chamber and allowing it to stand is as follows: First, spray a 1mm thick layer of the second insulating coating and wait 10 minutes for it to dry; second, spray a 1mm thick layer of the second insulating coating and wait 10 minutes for it to dry; third, spray a 1mm thick layer of the second insulating coating and wait 10 minutes for it to dry. By applying the second insulating coating to the furnace bottom 110 in layers and allowing it to stand, the coating becomes more uniform and the effect is better. Ultimately, the furnace bottom 110 is coated with a 3mm thick layer of the second insulating coating.

[0105] Of course, in other embodiments, the thickness of the second insulating coating applied to the inner wall of the furnace bottom 110 near the heating chamber can also be 4mm or 6mm, etc., and there is no special limitation on this. It can be done by spraying 1mm each time and allowing it to stand for 10 minutes to dry in layers.

[0106] In one embodiment, after the step of vacuum calcining the single crystal furnace at a second preset power for a second preset time, the method further includes: spraying a third heat-insulating coating onto the furnace cover 130, furnace cylinder 120, and furnace bottom 110 of the single crystal furnace and allowing it to stand; and vacuum calcining the single crystal furnace at a third preset power for a third preset time. The third heat-insulating coating is different from both the first and second heat-insulating coatings, and is one of a reflective heat-insulating coating, a radiative heat-insulating coating, and a barrier heat-insulating coating.

[0107] By coating the inner walls of the furnace cover 130, furnace cylinder 120 and furnace bottom 110 near the heating chamber with a third heat-insulating coating and allowing it to stand, the third heat-insulating coating can be surface-dried on the furnace cover 130, furnace cylinder 120 and furnace bottom 110. Then, the single crystal furnace is vacuum-calcined with a third preset power for a third preset time, so that the third heat-insulating coating is completely adhered to the inner wall of the heating chamber.

[0108] In one embodiment, the third thermal insulation coating is a reflective thermal insulation coating.

[0109] In one specific embodiment, when the third insulating coating is a reflective heat-insulating coating, the specific process of applying the third insulating coating to the inner wall of the furnace cover 130 near the heating chamber and allowing it to stand is as follows: First, spray a 1mm thick layer of the third insulating coating and wait 10 minutes for it to dry; second, spray a 1mm thick layer of the third insulating coating and wait 10 minutes for it to dry; third, spray a 1mm thick layer of the third insulating coating and wait 10 minutes for it to dry; fourth, spray a 1mm thick layer of the third insulating coating and wait 10 minutes for it to dry. By applying the third insulating coating to the furnace cover 130 in layers and allowing it to stand, the coating becomes more uniform and the effect is better. Ultimately, the furnace cover 130 is coated with a 4mm thick layer of the third insulating coating.

[0110] Of course, in other embodiments, the thickness of the third insulating coating applied to the inner wall of the furnace cover 130 near the heating chamber can also be 3mm or 5mm, etc., and there is no special limitation on this. It can be done by layering spraying 1mm each time and allowing it to stand for 10 minutes to dry.

[0111] In one specific embodiment, when the third thermal insulation coating is a reflective thermal insulation coating, the specific process of applying the third thermal insulation coating to the inner wall of the furnace cylinder 120 near the heating chamber and allowing it to stand is as follows: First, spray a 1mm thick layer of the third thermal insulation coating and wait 10 minutes for it to dry; second, spray a 1mm thick layer of the third thermal insulation coating and wait 10 minutes for it to dry; third, spray a 1mm thick layer of the third thermal insulation coating and wait 10 minutes for it to dry; fourth, spray a 1mm thick layer of the third thermal insulation coating and wait 10 minutes for it to dry. By applying the third thermal insulation coating to the furnace cylinder 120 in layers and allowing it to stand, the coating becomes more uniform and the effect is better. Ultimately, the furnace cylinder 120 is coated with a 4mm thick layer of the third thermal insulation coating.

[0112] Of course, in other embodiments, the thickness of the third insulating coating applied to the inner wall of the furnace cylinder 120 near the heating chamber can also be 2mm, 3mm, or 5mm, etc., and there is no special limitation on this. It can be done by layering spraying 1mm each time and allowing it to stand for 10 minutes to dry.

[0113] In one specific embodiment, when the third insulating coating is a reflective heat-insulating coating, the specific process of applying the third insulating coating to the inner wall of the furnace bottom 110 near the heating chamber and allowing it to stand is as follows: First, spray a 1mm thick layer of the third insulating coating and wait 10 minutes for it to dry completely; then spray a second 1mm thick layer of the third insulating coating and wait 10 minutes for it to dry completely. By applying the third insulating coating to the furnace bottom 110 in layers and allowing it to stand, the coating becomes more uniform and the effect is better. Ultimately, the furnace bottom 110 is coated with a 2mm thick layer of the third insulating coating.

[0114] Of course, in other embodiments, the thickness of the third insulating coating applied to the inner wall of the furnace bottom 110 near the heating chamber can also be 1mm, 3mm, or 4mm, etc., and there is no special limitation on this. It can be done by layering spraying 1mm each time and allowing it to stand for 10 minutes to dry.

[0115] It should be noted that the order in which the barrier thermal insulation coating, reflective thermal insulation coating, and radiative thermal insulation coating are applied in the preparation method of the single crystal furnace described in this application is not limited. The coating can be applied in the order described in the above embodiments, or in the order of radiative thermal insulation coating, barrier thermal insulation coating, and reflective thermal insulation coating, or in the order of reflective thermal insulation coating, barrier thermal insulation coating, and radiative thermal insulation coating.

[0116] In one embodiment, the thickness of the reflective heat-insulating coating applied to the inner wall of the furnace bottom 110 is defined as the first thickness h1, the thickness of the radiative heat-insulating coating applied to the inner wall of the furnace bottom 110 is defined as the second thickness h2, and the thickness of the barrier heat-insulating coating applied to the inner wall of the furnace bottom 110 is defined as the third thickness h3; wherein, the first thickness h1 is less than the second thickness h2, and the second thickness h2 is less than the third thickness h3.

[0117] During crystal growth, the furnace bottom 110 is directly subjected to heat conduction from the internal thermal system composed of graphite components 140. The circulating cooling water in the furnace bottom 110 protects the furnace bottom plate, thus carrying away the heat transferred from the growth thermal system to the furnace bottom plate, resulting in energy loss. Therefore, the thickness h3 of the barrier thermal insulation coating on the furnace bottom 110 is set to be greater than the thickness h2 of the reflective thermal insulation coating and the thickness h1 of the radiative thermal insulation coating. This results in a thicker barrier thermal insulation coating, effectively reducing the heat exchange rate between the internal thermal system composed of graphite components 140 and the furnace bottom 110, while also effectively reducing the heat carried away by the protective circulating cooling water in the furnace bottom 110, further reducing heat loss.

[0118] In one specific embodiment, the ratio of the first thickness h1 to the second thickness h2 and the third thickness h3 is 2:3:5.

[0119] In another specific embodiment, the ratio of the first thickness h1 to the second thickness h2 and the third thickness h3 is 3:4:5.

[0120] In one embodiment, the thickness of the reflective heat-insulating coating applied to the inner wall of the furnace cylinder 120 is the fourth thickness h4, the thickness of the radiative heat-insulating coating applied to the inner wall of the furnace cylinder 120 is the fifth thickness h5, and the thickness of the barrier heat-insulating coating applied to the inner wall of the furnace cylinder 120 is the sixth thickness h6; wherein, the fourth thickness h4 and the sixth thickness h6 are both greater than the fifth thickness h5, and the values ​​of the fourth thickness h4 and the sixth thickness h6 are the same or different.

[0121] During crystal growth, the furnace cylinder 120 is subjected to direct heat radiation from the internal thermal system composed of graphite components 140 and heat conduction via convection from the internal vacuum gas. The circulating cooling water in the furnace cylinder 120, designed to protect it, carries away the heat transferred from the growth thermal system, resulting in energy loss. Therefore, the thickness h4 of the reflective thermal insulation coating and the thickness h6 of the barrier thermal insulation coating on the furnace cylinder 120 are set to be greater than the thickness h5 of the radiative thermal insulation coating. This results in thicker reflective and barrier thermal insulation coatings, effectively reducing the heat exchange rate between the internal thermal system composed of graphite components 140 and the furnace cylinder 120, while also reducing the heat carried away by the protective circulating water in the furnace cylinder 120, further minimizing heat loss.

[0122] In one specific embodiment, the ratio of the fourth thickness h4 to the fifth thickness h5 and the sixth thickness h6 is 4:2:4.

[0123] In another specific embodiment, the ratio of the fourth thickness h4 to the fifth thickness h5 and the sixth thickness h6 is 4:2:3.

[0124] In another specific embodiment, the ratio of the fourth thickness h4 to the fifth thickness h5 and the sixth thickness h6 is 3:2:4.

[0125] In another specific embodiment, the ratio of the fourth thickness h4 to the fifth thickness h5 and the sixth thickness h6 is 4:3:4.

[0126] In one embodiment, the thickness of the reflective heat-insulating coating applied to the inner wall of the furnace cover 130 is the seventh thickness h7, the thickness of the radiative heat-insulating coating applied to the inner wall of the furnace cover 130 is the eighth thickness h8, and the thickness of the barrier heat-insulating coating applied to the inner wall of the furnace cover 130 is the ninth thickness h9; wherein, the eighth thickness h8 and the ninth thickness h9 are both less than the seventh thickness h7, and the values ​​of the eighth thickness h8 and the ninth thickness h9 are the same or different.

[0127] During crystal growth, the furnace cover 130 is directly exposed to heat radiation from the crystal rod and molten silicon surface. The circulating cooling water in the furnace cover 130 carries away energy transferred from the growth heat system to the furnace cover 130, resulting in energy loss. Therefore, the thickness h7 of the reflective heat-insulating coating on the furnace cover 130 is set to be greater than the thickness h8 of the radiation-insulating coating and the thickness h9 of the barrier-insulating coating. This results in a thicker reflective heat-insulating coating, effectively reducing the heat exchange rate between the internal thermal system composed of the graphite components 140 and the furnace cover 130. Simultaneously, it effectively reduces the heat carried away by the protective circulating water in the furnace cylinder 120, further reducing heat loss.

[0128] In one specific embodiment, the ratio of the seventh thickness h7 to the eighth thickness h8 and the ninth thickness h9 is 4:3:3.

[0129] In another specific embodiment, the ratio of the seventh thickness h7 to the eighth thickness h8 and the ninth thickness h9 is 4:3:2.

[0130] In another specific embodiment, the ratio of the seventh thickness h7 to the eighth thickness h8 and the ninth thickness h9 is 4:2:3.

[0131] In another specific embodiment, the ratio of the seventh thickness h7 to the eighth thickness h8 and the ninth thickness h9 is 4:2:2.

[0132] In the method for preparing the single crystal furnace in this application, the heat transfer mode of the single crystal growth thermal system and different parts of the furnace body (furnace bottom 110, furnace cylinder 120 and furnace cover 130) is different, which results in different thicknesses of the barrier heat insulation coating, reflective heat insulation coating and radiative heat insulation coating applied to the furnace bottom 110, furnace cylinder 120 and furnace cover 130, thereby achieving a better heat insulation effect.

[0133] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0134] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A single crystal furnace, characterized in that, The single crystal furnace includes a furnace bottom (110), a furnace cylinder (120), and a furnace cover (130); the furnace bottom (110) is fixedly connected to the furnace cylinder (120), and the furnace cover (130) is detachably connected to the side of the furnace cylinder (120) away from the furnace bottom (110); When the furnace cover (130) is connected to the furnace cylinder (120), the furnace bottom (110), the furnace cylinder (120) and the furnace cover (130) can be together arranged to form a heating chamber; the inner walls of the furnace bottom (110), the furnace cylinder (120) and the furnace cover (130) near the heating chamber are all coated with heat-insulating material; The insulation material coated on the inner wall of the furnace bottom (110) includes reflective heat insulation coating, radiative heat insulation coating and barrier heat insulation coating. The thickness of the reflective heat-insulating coating applied to the inner wall of the furnace bottom (110) is defined as the first thickness h1, the thickness of the radiative heat-insulating coating applied to the inner wall of the furnace bottom (110) is defined as the second thickness h2, and the thickness of the barrier heat-insulating coating applied to the inner wall of the furnace bottom (110) is defined as the third thickness h3; wherein, the first thickness h1 is less than the second thickness h2, and the second thickness h2 is less than the third thickness h3. The thermal insulation material coated on the inner wall of the furnace cylinder (120) includes reflective thermal insulation coating, radiative thermal insulation coating, and barrier thermal insulation coating; the thickness of the reflective thermal insulation coating on the inner wall of the furnace cylinder (120) is the fourth thickness h4, the thickness of the radiative thermal insulation coating on the inner wall of the furnace cylinder (120) is the fifth thickness h5, and the thickness of the barrier thermal insulation coating on the inner wall of the furnace cylinder (120) is the sixth thickness h6; wherein, the fourth thickness h4 and the sixth thickness h6 are both greater than the fifth thickness h5, and the values ​​of the fourth thickness h4 and the sixth thickness h6 are the same or different. The thermal insulation material coated on the inner wall of the furnace cover (130) includes reflective thermal insulation coating, radiative thermal insulation coating and barrier thermal insulation coating; the thickness of the reflective thermal insulation coating coated on the inner wall of the furnace cover (130) is the seventh thickness h7, the thickness of the radiative thermal insulation coating coated on the inner wall of the furnace cover (130) is the eighth thickness h8, and the thickness of the barrier thermal insulation coating coated on the inner wall of the furnace cover (130) is the ninth thickness h9; wherein, the eighth thickness h8 and the ninth thickness h9 are both less than the seventh thickness h7, and the values ​​of the eighth thickness h8 and the ninth thickness h9 are the same or different.

2. The single crystal furnace according to claim 1, characterized in that, The insulation material has a multi-layer structure.

3. The single crystal furnace according to claim 2, characterized in that, The thickness h of the insulation material meets the following condition: 10mm≤h≤20mm.

4. A method for preparing a single crystal furnace, characterized in that, The method for preparing the single crystal furnace includes: Clean the walls of the heating chamber of the single crystal furnace; Thermal insulation material is coated on the inner walls of the furnace cover (130), furnace cylinder (120) and furnace bottom (110) of the single crystal furnace on the side near the heating chamber; The single crystal furnace is vacuum-calcined at a preset power for a preset duration; Wherein, the thickness of the reflective heat-insulating coating applied to the inner wall of the furnace bottom (110) is the first thickness h1, the thickness of the radiation heat-insulating coating applied to the inner wall of the furnace bottom (110) is the second thickness h2, and the thickness of the barrier heat-insulating coating applied to the inner wall of the furnace bottom (110) is the third thickness h3; the first thickness h1 is less than the second thickness h2, and the second thickness h2 is less than the third thickness h3. The thickness of the reflective heat-insulating coating applied to the inner wall of the furnace cylinder (120) is defined as the fourth thickness h4, the thickness of the radiative heat-insulating coating applied to the inner wall of the furnace cylinder (120) is defined as the fifth thickness h5, and the thickness of the barrier heat-insulating coating applied to the inner wall of the furnace cylinder (120) is defined as the sixth thickness h6; both the fourth thickness h4 and the sixth thickness h6 are greater than the fifth thickness h5, and the values ​​of the fourth thickness h4 and the sixth thickness h6 are the same or different. The thickness of the reflective heat-insulating coating applied to the inner wall of the furnace cover (130) is the seventh thickness h7, the thickness of the radiative heat-insulating coating applied to the inner wall of the furnace cover (130) is the eighth thickness h8, and the thickness of the barrier heat-insulating coating applied to the inner wall of the furnace cover (130) is the ninth thickness h9; the eighth thickness h8 and the ninth thickness h9 are both less than the seventh thickness h7, and the values ​​of the eighth thickness h8 and the ninth thickness h9 are the same or different.

5. The method for preparing a single crystal furnace according to claim 4, characterized in that, The inner walls of the furnace cover (130), furnace cylinder (120) and furnace bottom (110) of the single crystal furnace near the heating chamber are coated with heat-insulating material. The steps of vacuum calcining the single crystal furnace at a preset power for a preset duration specifically include: The inner walls of the furnace cover (130), furnace cylinder (120) and furnace bottom (110) near the heating chamber of the single crystal furnace are coated with a first heat-insulating coating and left to stand. The single crystal furnace is vacuum-calcined at a first preset power for a first preset duration; The first thermal insulation coating is one of a reflective thermal insulation coating, a radiative thermal insulation coating, and a barrier thermal insulation coating.

6. The method for preparing a single crystal furnace according to claim 5, characterized in that, After the step of vacuum calcining the single crystal furnace at a first preset power for a first preset time, the method further includes: The second heat-insulating coating is applied to the furnace cover (130), furnace cylinder (120) and furnace bottom (110) of the single crystal furnace and left to stand; The single crystal furnace is vacuum-calcined at a second preset power for a second preset duration; The second thermal insulation coating is different from the first thermal insulation coating. The second thermal insulation coating is one of reflective thermal insulation coating, radiative thermal insulation coating, and barrier thermal insulation coating.

7. The method for preparing a single crystal furnace according to claim 6, characterized in that, After the step of vacuum calcining the single crystal furnace at a second preset power for a second preset time, the method further includes: A third heat-insulating coating is sprayed onto the furnace cover (130), furnace cylinder (120), and furnace bottom (110) of the single crystal furnace and left to stand; The single crystal furnace is vacuum-calcined at a third preset power for a third preset duration; The third thermal insulation coating is different from both the first and second thermal insulation coatings. The third thermal insulation coating is one of the following: reflective thermal insulation coating, radiative thermal insulation coating, and barrier thermal insulation coating.

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