High-sealing single crystal furnace with lengthened furnace chamber

Abstract

The invention belongs to the technical field of extended single crystal furnaces, and particularly relates to a high-sealing single crystal furnace with an extended furnace chamber, which comprises a lower furnace body, the bottom end of the lower furnace body is fixedly connected with a furnace seat; an upper furnace body is connected to the lower furnace body in a sliding manner; a hydraulic cylinder is arranged to drive a first top plate to slide upwards or downwards and synchronously drive an upper furnace body to slide on the outer wall of a lower furnace body so as to adjust the extension or shortening of a furnace chamber, meanwhile, the upper furnace body synchronously drives an upper crucible to slide upwards or downwards on the outer wall of a lower crucible so as to adjust the extension or shortening of the crucible, and a vacuum technology is adopted in the furnace. Under the vacuum environment in the furnace, due to the close fit movement design of all the components, external gas invasion is effectively prevented, the purity of the single crystal growth environment is ensured, the sealing performance of the furnace body is greatly improved, the crucible is prolonged along with the furnace chamber, it is ensured that the longitudinal temperature gradient from the surface of a melt to the upper portion of the furnace chamber becomes stable, and the temperature gradient is stable. Therefore, the crystal growth is more stable, and the probability of dislocation proliferation and crystal cracking is reduced.

Description

Technical Field

[0001] This invention belongs to the field of extended single crystal furnace technology, specifically a highly sealed single crystal furnace with an extended furnace chamber. Background Technology

[0002] A single crystal furnace is a key piece of equipment used in the semiconductor industry, solar photovoltaic and other fields to prepare high-purity single crystal materials. Its core principle is to recrystallize polycrystalline raw materials and powder materials into single crystals with highly ordered atomic arrangement by precisely controlling the high-temperature melting and crystal growth process.

[0003] A patent application with publication number CN119372789A discloses a single crystal growth furnace, including an outer shell. An electromagnetic limiting sleeve is movably sleeved on the outside of the outer shell. An mounting plate is fixedly connected to the side of the electromagnetic limiting sleeve. A first mounting bracket is installed on the outside of the side of the electromagnetic limiting sleeve by fastening bolts. This single crystal growth furnace mainly controls the magnetic field of the electromagnet to change the temperature by detecting the temperature change of the crystallizing raw material inside the outer shell, thereby ensuring the stability of the raw material during crystallization.

[0004] In the application of single crystal furnaces, the aforementioned single crystal growth furnaces adjust the magnetic field by detecting the temperature change of the raw material inside the shell, thereby ensuring the stability of the raw material crystallization. However, traditional single crystal furnace designs have limitations. They are usually only suitable for growing crystal rods of a certain fixed size, which greatly limits the flexibility and adaptability of the crystal production process. Especially when it is necessary to produce crystal rods of different sizes, traditional single crystal furnaces often require replacing the entire furnace chamber and the internal crucible. This process is not only time-consuming and labor-intensive, but also highly complex, which can easily increase the production time.

[0005] Therefore, the present invention provides a highly airtight single crystal furnace with an extended furnace chamber. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0007] The technical solution adopted by the present invention to solve its technical problem is as follows: The present invention provides a high-sealing single crystal furnace with an extended furnace chamber, comprising a lower furnace body; a furnace base is fixedly connected to the bottom end of the lower furnace body; an upper furnace body is slidably connected to the lower furnace body; a hydraulic cylinder is fixedly connected to the furnace base; a No. 1 top plate is fixedly connected to the output end of the hydraulic cylinder, the No. 1 top plate is located at the bottom of the upper furnace body, and the No. 1 top plate is slidably connected to the outer wall of the lower furnace body; a plurality of lifting blocks are fixedly connected to the inner wall of the upper furnace body; a bracket is fixedly connected to the center of the lower furnace body; a lower crucible is fixedly connected to the bracket; an upper crucible is slidably connected to the outer wall of the lower crucible, and the upper crucible is attached to the plurality of lifting blocks.

[0008] Preferably, two support frames are fixedly connected to each other on the furnace base, and the first top plate is slidably connected to the outer wall of the support frame; the inner wall of the support frame is slidably connected to multiple limiting blocks through the second elastic element, and the cross-sectional shape of the limiting blocks is trapezoidal.

[0009] Preferably, a fixed seat is fixedly connected to the furnace base; a lifting frame is slidably connected to the inner wall of the fixed seat; a crystal pulling assembly is fixedly connected to the lifting frame; a second top plate is fixedly connected to the outer wall of the first top plate near the lifting frame, and the second top plate is fixedly connected to the lifting frame.

[0010] Preferably, a heater is fixedly connected to the bottom of the lower furnace body; a filling groove is provided on the first top plate and near the lower part of the upper furnace body, and multiple first filling pads are fixedly connected in the filling groove. The multiple first filling pads are stacked and installed in a stacked manner. The cross-sectional shape of the first filling pad is annular, and the material of the first filling pad is ceramic fiber composite material.

[0011] Preferably, a fixing plate is fixedly connected to the top outer wall of the lower furnace body; multiple No. 2 filling pads are fixedly connected between the fixing plate and the outer wall of the lower furnace body, and the multiple No. 2 filling pads are stacked; a No. 3 filling pad is fixedly connected to the bottom inner wall of the upper furnace body; the cross-sectional shape of the No. 2 filling pad and the No. 3 filling pad are both annular, and the material of the No. 2 filling pad and the No. 3 filling pad is expanded graphite.

[0012] Preferably, a sliding plate is slidably connected to the outer wall of the lower furnace body near the top of the No. 3 filling pad; a fixed cylinder is fixedly connected to the sliding plate; a sliding rod is slidably connected to the inner wall of the fixed cylinder, the sliding rod passes through the fixed plate and is supported below the No. 2 filling pad, and a ring plate is fixedly connected to the sliding rod, with the ring plate located between the sliding rod and the No. 2 filling pad; a No. 1 elastic element is fixedly connected inside the fixed cylinder.

[0013] Preferably, an oil pipe is fixedly connected to the interior of the upper furnace body near the fixed plate; a heat insulation pad is fixedly connected to the outer wall of the lower furnace body near the oil pipe, and the heat insulation pad has an annular cross-sectional shape.

[0014] Preferably, the sliding plate is provided with oil guide grooves, and three oil guide grooves are provided, with one side opening of the oil guide grooves close to the outer wall of the lower furnace body.

[0015] Preferably, a fixing frame is fixedly connected inside the upper furnace body, and the fixing frame is located above the upper crucible; a water-cooled heat shield is fixedly connected to the inner ring of the fixing frame.

[0016] Preferably, a water guide pipe is fixedly connected to the outer wall of the upper furnace body; a diversion groove is formed inside the upper furnace body near the water guide pipe, and the diversion groove has two outlets; a circular slot is formed inside the fixing frame, one end of which can be connected to one outlet of the diversion groove, and the other end of which is connected to the water-cooled heat shield; a guide groove is formed inside the upper furnace body, the guide groove is spiral in shape, and the guide groove can be connected to the other outlet of the diversion groove; a drain pipe is fixedly connected to the outer wall of the upper furnace body, and the drain pipe is connected to the end of the guide groove away from the diversion groove.

[0017] The beneficial effects of this invention are as follows: 1. The present invention discloses a highly sealed single crystal furnace with an extended furnace chamber. A hydraulic cylinder output end drives a top plate to slide up or down, simultaneously causing the upper furnace body to slide against the outer wall of the lower furnace body, thereby adjusting the extension or shortening of the furnace chamber. Simultaneously, the upper furnace body drives the upper crucible to slide up or down against the outer wall of the lower crucible, adjusting the extension or shortening of the crucible. The furnace employs vacuum technology. Under vacuum conditions, the tight-fitting and moving design between components not only effectively prevents external gas intrusion, ensuring the purity of the single crystal growth environment, but also significantly improves the sealing performance of the furnace body. This highly sealed structure is crucial for maintaining a constant temperature and pressure field within the furnace, helping to reduce impurity incorporation during single crystal growth and improving the quality and purity of the single crystal. Furthermore, the vacuum... The application of air technology also promotes uniform heat distribution, allowing single crystals to undergo more balanced heat treatment during growth, further optimizing the crystal structure. The entire process ensures the stability and sealing of the single crystal furnace during furnace chamber length adjustment, effectively improving the flexibility and applicability of the single crystal furnace. It can better meet the requirements of single crystal furnace chamber length under different process conditions. As the furnace chamber is extended, the longitudinal temperature gradient from the melt surface to the upper part of the furnace chamber becomes more stable, which makes crystal growth more stable and reduces the probability of dislocation multiplication and crystal cracking. By setting up a single crystal furnace that can extend the furnace chamber and internal crucible, it replaces the traditional single crystal furnace that requires replacement of parts, saving the time of replacing parts during production and thus ensuring the efficiency of crystal rod production.

[0018] 2. The present invention discloses a highly airtight single crystal furnace with an extended furnace chamber. Multiple stacked annular No. 2 filling pads are attached between the fixed plate and the inner wall of the upper furnace body, and annular No. 3 filling pads are fixed to the bottom inner wall of the upper furnace body and attached to the outer wall of the lower furnace body. The expanded graphite No. 2 and No. 3 filling pads have excellent high-temperature resistance and sealing properties. When the furnace chamber temperature rises, the No. 2 and No. 3 filling pads expand and fit more tightly at the connection, forming a reliable sealing barrier. This effectively prevents gas leakage and the entry of outside air, further ensuring the stability and purity of the single crystal growth environment inside the furnace. This sealing design based on expanded graphite material is not only suitable for single crystal furnaces operating at high temperatures, but also... The sealing requirements under these conditions are met, and its excellent elasticity and adaptability allow it to maintain a long-term sealing effect, reducing the risk of seal failure due to aging and deformation of the seals. The stacked design of the No. 2 filler pads also enhances the redundancy of the sealing structure. Even if some No. 2 filler pads are damaged or worn, the others can continue to perform their sealing function, ensuring the reliability and safety of the single crystal furnace's long-term operation. Furthermore, the annular cross-sectional shape of the No. 2 and No. 3 filler pads matches the shape of the connection between the lower and upper furnace bodies, resulting in a more fitted and uniform seal, further improving the sealing effect. This refined sealing design provides a strong guarantee for the stable operation of the single crystal furnace under harsh working conditions such as high temperature and high pressure. Attached Figure Description

[0019] The invention will now be further described with reference to the accompanying drawings.

[0020] Figure 1 This is a perspective view of the present invention; Figure 2 This is a partial structural cross-sectional view of the upper furnace body in this invention; Figure 3 This is a schematic diagram of the lifting block in this invention; Figure 4 This is a partial structural cross-sectional view of the lower furnace body in this invention; Figure 5 This is a schematic diagram of the oil guide groove in this invention; Figure 6 This is a schematic diagram of the structure of the No. 1 filling pad in this invention.

[0021] In the diagram: 1. Lower furnace body; 11. Furnace base; 12. Upper furnace body; 13. Hydraulic cylinder; 14. Top plate No. 1; 15. Lifting block; 16. Bracket; 17. Lower crucible; 18. Upper crucible; 2. Fixed seat; 21. Lifting frame; 22. Crystal pulling assembly; 23. Top plate No. 2; 3. Heater; 31. Filling pad No. 1; 4. Fixed plate; 41. Filling pad No. 2; 42. Filling pad No. 3; 5. Fixed cylinder; 51. Sliding rod; 52. Elastic element No. 1; 53. Sliding plate; 6. Oil pipe; 61. Heat insulation pad; 7. Oil guide groove; 71. Fixed frame; 72. Water-cooled heat shield; 8. Water guide pipe; 81. Diversion groove; 82. Circular hole groove; 83. Flow guide groove; 84. Drain pipe; 9. Support frame; 91. Limiting block. Detailed Implementation

[0022] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0023] like Figures 1 to 4 , Figure 6As shown in the embodiment of the present invention, a highly sealed single crystal furnace with an extended furnace chamber includes a lower furnace body 1; a furnace base 11 is fixedly connected to the bottom end of the lower furnace body 1; an upper furnace body 12 is slidably connected to the lower furnace body 1; a hydraulic cylinder 13 is fixedly connected to the furnace base 11; a top plate 14 is fixedly connected to the output end of the hydraulic cylinder 13, the top plate 14 is located at the bottom of the upper furnace body 12, and the top plate 14 is slidably connected to the outer wall of the lower furnace body 1; a plurality of lifting blocks 15 are fixedly connected to the inner wall of the upper furnace body 12; a bracket 16 is fixedly connected to the center of the interior of the lower furnace body 1; a lower crucible 17 is fixedly connected to the bracket 16; an upper crucible 18 is slidably connected to the outer wall of the lower crucible 17, and the upper crucible 18 is attached to the plurality of lifting blocks 15.In applications of high-sealing single crystal furnaces with extended chambers, the lower furnace body 1 serves as the main chamber, with the furnace base 11 supporting it below. The upper furnace body 12 slides along the outer wall of the lower furnace body 1 as an extended chamber. A bracket 16 is fixed at the center inside the lower furnace body 1, supporting the lower crucible 17, which is the main crucible. The upper crucible 18 slides along the outer wall of the lower crucible 17 as an extended crucible. When adjusting the high-sealing single crystal furnace to extend the chamber, the output end of the hydraulic cylinder 13 drives the first top plate 14 to slide upwards. The first top plate 14, supported at the bottom of the upper furnace body 12, pushes upwards, causing the upper furnace body 12 to slide upwards onto the lower furnace body. The outer wall of furnace 1 extends the furnace chamber. The first top plate 14 seals the connection between the upper furnace body 12 and the lower furnace body 1. Simultaneously, the upper furnace body 12 drives the upper crucible 18, supported by multiple lifting blocks 15, to slide upwards onto the outer wall of the lower crucible 17, extending the crucible. When the furnace chamber needs to be shortened, the output end of the hydraulic cylinder 13 is controlled to drive the first top plate 14 downwards, causing the upper furnace body 12 to slide down against the outer wall of the lower furnace body 1, shortening the furnace chamber. Simultaneously, the upper furnace body 12, relying on its own weight, drives the upper crucible 18, supported by multiple lifting blocks 15, to slide down against the outer wall of the lower crucible 17, completing the crucible shortening operation. The lower furnace body 1 and the upper... The furnace body 12 and the lower crucible 17 and upper crucible 18 move in close contact. Vacuum technology is used inside the furnace. This close-fitting design of the components in the vacuum environment effectively prevents external gas intrusion, ensuring the purity of the single crystal growth environment. It also significantly improves the furnace's sealing performance. This highly sealed structure is crucial for maintaining a constant temperature and pressure field inside the furnace, helping to reduce impurity incorporation during single crystal growth and improving the quality and purity of the single crystal. Furthermore, the application of vacuum technology promotes uniform heat distribution, allowing the single crystal to undergo more balanced heat treatment during growth, further enhancing its quality. By optimizing the crystal structure of single crystals, the entire process ensures the stability and sealing of the single crystal furnace during furnace chamber length adjustment, effectively improving the flexibility and applicability of the single crystal furnace. It better meets the requirements for furnace chamber length under different process conditions. As the furnace chamber extends, the longitudinal temperature gradient from the melt surface to the upper part of the furnace chamber becomes smoother, resulting in more stable crystal growth and reducing the probability of dislocation multiplication and crystal cracking. By setting up a single crystal furnace that can extend the furnace chamber and internal crucible, it replaces the traditional single crystal furnace that requires replacing parts, saving time on parts replacement during production and thus ensuring the efficiency of crystal rod production.

[0024] Two support frames 9 are fixedly connected to the furnace base 11, and a first top plate 14 is slidably connected to the outer wall of the support frame 9. Multiple limiting blocks 91 are slidably connected to the inner wall of the support frame 9 via a second elastic element, and the limiting blocks 91 have a trapezoidal cross-sectional shape. When the furnace chamber and crucible are extended, the two support frames 9 are fixed to the furnace base 11 and located on both sides of the lower furnace body 1 as supports. During the sliding process of the first top plate 14 pushed by the output end of the hydraulic cylinder 13, the first top plate 14 slides synchronously on the two support frames 9, and the first top plate 14 can press the inclined surface of the trapezoidal limiting block 91, causing the limiting block... The second elastic element is retracted into the support frame 9 by the compression of the first top plate 14. After the first top plate 14 passes the limiting block 91, the second elastic element pushes the limiting block 91 out. The upper surface of the trapezoidal limiting block 91 supports the bottom of the first top plate 14. At this time, the output end of the hydraulic cylinder 13 still provides the main support for the first top plate 14, while the limiting block 91 provides stable auxiliary support for the first top plate 14, ensuring the stability of the upper furnace body 12 and the upper crucible 18 after rising, making the furnace chamber extension operation more reliable. The second elastic element is set as a spring, and when the limiting block 91 is pushed out by the elastic force of the second elastic element, most of the limiting block 91... The first top plate 14 remains inside the support frame 9. Each time it slides between two limit blocks 91, it adjusts to a set height, adaptable to the required extension height of the furnace chamber. When the hydraulic cylinder 13 drives the first top plate 14 downwards, the upper surface of the trapezoidal limit block 91 needs to be manually pressed, causing the limit block 91 to retract into the support frame 9. After the first top plate 14 passes the limit block 91, the second elastic element pushes the limit block 91 out again, preparing for the next upward movement of the first top plate 14. This design enhances the stability of the entire extended furnace chamber structure, ensuring the furnace chamber extension... Based on the flexible implementation of the length and shortening functions, the reliability and safety of the high-sealing single crystal furnace during operation are further improved, providing a solid equipment guarantee for the high-quality growth of single crystals. At the same time, when the No. 1 top plate 14 is located on the upper plane of the two limiting blocks 91, since the width of the No. 1 top plate 14 is greater than the distance between the two limiting blocks 91, part of the limiting blocks 91 are still pressed between the support frame 9 and the inner wall of the No. 1 top plate 14. Relying on the No. 2 elastic element to squeeze the limiting blocks 91, one end of the limiting block 91 is pressed against the inner wall of the No. 1 top plate 14, which plays a role in auxiliary support and limiting of the No. 1 top plate 14.

[0025] like Figures 1 to 3As shown, a fixed seat 2 is fixedly connected to the furnace base 11; a lifting frame 21 is slidably connected to the inner wall of the fixed seat 2; a crystal pulling assembly 22 is fixedly connected to the lifting frame 21; a second top plate 23 is fixedly connected to the outer wall of the first top plate 14 near the lifting frame 21, and the second top plate 23 is fixedly connected to the lifting frame 21; when the crystal growth furnace chamber is extended, the position of the crystal pulling furnace chamber also needs to be raised. The lifting frame 21 slides inside the fixed seat 2 as the extension position, and the crystal pulling assembly 22 is used to enter the crystal pulling furnace chamber inside the crystal growth furnace chamber. The output end of the hydraulic cylinder 13 drives the first top plate 14 to slide upward to extend the crystal growth furnace chamber. The first top plate 14 synchronously pulls... The lifting frame 21 connected to the second top plate 23 and the crystal pulling furnace chamber slide upwards. The lifting frame 21 slides on the inner wall of the fixed base 2 to achieve positional adjustment of the crystal pulling furnace chamber. When the furnace chamber is shortened, the output end of the hydraulic cylinder 13 is controlled to drive the first top plate 14 to slide down. The first top plate 14 drives the lifting frame 21 connected to the second top plate 23 and the crystal pulling furnace chamber to slide down synchronously, so that the crystal pulling furnace chamber returns to the appropriate position. This synchronous adjustment design ensures the coordination between the crystal growth furnace chamber and the crystal pulling furnace chamber during the furnace chamber length adjustment process, avoids operation problems caused by mismatch between the two positions, and further improves the stability and reliability of the single crystal furnace operation.

[0026] like Figures 1 to 4 , Figure 6 As shown, a heater 3 is fixedly connected to the bottom of the lower furnace body 1; a filling groove is provided on the first top plate 14 near the lower part of the upper furnace body 12, and multiple first filling pads 31 are fixedly connected in the filling groove. The multiple first filling pads 31 are stacked and installed in a stacked manner. The cross-sectional shape of the first filling pad 31 is annular, and the material of the first filling pad 31 is ceramic fiber composite material. When the silicon material is heated in the crucible, the heater 3 is installed inside the lower furnace body 1 and located below the lower crucible 17 to heat and melt the silicon material in the lower crucible 17. The multiple stacked annular first filling pads 31 fill the filling groove of the first top plate 14, and the material of the first filling pad 31 is selected as... The ceramic fiber composite material has excellent high temperature resistance and heat insulation effect. Multiple No. 1 filling pads 31 can be tightly fitted to the connection between the upper furnace body 12 and the lower furnace body 1 to seal the connection. During the extension and shortening of the furnace chamber, as the No. 1 top plate 14 moves up and down, the No. 1 filling pads 31 always maintain a tight fit with the connection between the upper furnace body 12 and the lower furnace body 1, effectively preventing heat loss and external gas intrusion, and further enhancing the sealing performance of the furnace body. At the same time, the stacked installation design of the No. 1 filling pads 31 allows them to adaptively adjust according to the actual gap at the connection between the upper furnace body 12 and the lower furnace body 1, ensuring the stability and reliability of the sealing effect.

[0027] like Figures 1 to 5As shown, a fixing plate 4 is fixedly connected to the top outer wall of the lower furnace body 1; multiple No. 2 filling pads 41 are fixedly connected between the fixing plate 4 and the outer wall of the lower furnace body 1, and the multiple No. 2 filling pads 41 are stacked; a No. 3 filling pad 42 is fixedly connected to the bottom inner wall of the upper furnace body 12; the cross-sectional shape of the No. 2 filling pad 41 and the No. 3 filling pad 42 is annular, and the material of the No. 2 filling pad 41 and the No. 3 filling pad 42 is expanded graphite; when sealing the connection between the lower furnace body 1 and the upper furnace body 12, the fixing plate is used. 4. Fixed at the angle of the protruding part of the lower furnace body 1, multiple stacked annular No. 2 filling pads 41 are attached between the fixing plate 4 and the inner wall of the upper furnace body 12, and are fixed to the bottom inner wall of the upper furnace body 12 and attached to the outer wall of the lower furnace body 1, in conjunction with annular No. 3 filling pads 42. The expanded graphite No. 2 filling pads 41 and No. 3 filling pads 42 have excellent high temperature resistance and sealing performance. When the furnace temperature rises, the No. 2 filling pads 41 and No. 3 filling pads 42 will expand and fit more tightly at the joint, forming a A reliable sealing barrier effectively prevents gas leakage and the entry of outside air, further ensuring the stability and purity of the single crystal growth environment inside the furnace. This sealing design based on expanded graphite material not only meets the sealing requirements of the single crystal furnace under high-temperature operating conditions, but also maintains a long-term sealing effect due to its good elasticity and adaptability, reducing the sealing failure caused by aging and deformation of the sealing components. At the same time, the stacked installation of the No. 2 filling pad 41 also enhances the redundancy of the sealing structure. Even if some of the No. 2 filling pads 41 are damaged or worn, the other No. 2 filling pads 41 can still continue to play a sealing role, ensuring the reliability and safety of the single crystal furnace in long-term operation. In addition, the annular cross-sectional shape of the No. 2 filling pad 41 and the No. 3 filling pad 42 matches the shape of the connection between the lower furnace body 1 and the upper furnace body 12, making the seal more fitted and uniform, further improving the sealing effect. This refined sealing design provides a strong guarantee for the stable operation of the single crystal furnace under harsh working conditions such as high temperature and high pressure.

[0028] A sliding plate 53 is slidably connected to the outer wall of the lower furnace body 1 near the top of the third filling pad 42; a fixed cylinder 5 is fixedly connected to the sliding plate 53; a sliding rod 51 is slidably connected to the inner wall of the fixed cylinder 5, the sliding rod 51 passes through the fixed plate 4 and is supported below the second filling pad 41, and an annular plate is fixedly connected to the sliding rod 51, with the annular plate located between the sliding rod 51 and the second filling pad 41; a first elastic element 52 is fixedly connected inside the fixed cylinder 5; when the second filling pad 41 and the third filling pad 42 seal the connection between the lower furnace body 1 and the upper furnace body 12, the annular plate on the sliding rod 51 and the sliding plate 53 respectively adhere to the surfaces of the second filling pad 41 and the third filling pad 42. As the furnace chamber extends, the upper furnace body 12 slides upward, which can squeeze the sliding rod 51 to retract. Inside the fixed cylinder 5, the first elastic element 52 contracts and is subjected to force, causing the sliding plate 53 at the bottom of the fixed cylinder 5 to work with the ring plate on the sliding rod 51 to further compress the third filling pad 42 and the second filling pad 41, thereby improving the sealing tightness. When the furnace chamber shortens, the upper furnace body 12 slides down under its own weight, and the first elastic element 52 also extends accordingly. During this process, the sliding rod 51 and its ring plate always keep in close contact with the second filling pad 41, and the sliding plate 53 and the surface of the third filling pad 42 also continuously abut against each other, ensuring the continuity and stability of the sealing structure. At the same time, the design of the fixed cylinder 5 also takes into account the thermal expansion factor. The sliding design of the sliding rod 51 in the fixed cylinder 5 reserves sufficient thermal expansion space to avoid sealing failure caused by thermal expansion and contraction.

[0029] like Figures 1 to 4As shown, an oil pipe 6 is fixedly connected to the interior of the upper furnace body 12 near the fixed plate 4; a heat insulation pad 61 is fixedly connected to the outer wall of the lower furnace body 1 near the oil pipe 6, and the heat insulation pad 61 has an annular cross-sectional shape. When the No. 3 filling pad 42 seals the connection between the lower furnace body 1 and the upper furnace body 12, the oil pipe 6 is first opened, and lubricating oil is injected into the interior of the oil pipe 6. The lubricating oil then enters the cavity formed between the lower furnace body 1 and the upper furnace body 12 and accumulates on the No. 3 filling pad 42. Subsequently, the oil pipe 6 is blocked, and a small amount of lubricating oil accumulates on the No. 3 filling pad 42. This not only provides an oil seal at the connection between the lower furnace body 1 and the upper furnace body 12, but also lubricates the outer wall of the lower furnace body 1, reducing friction when the upper furnace body 12 and the No. 3 filling pad 42 slide upwards. This design effectively reduces wear between components and extends the service life of the equipment. At the same time, the oil film formed by the lubricating oil can also prevent external damage to a certain extent. Impurities entering the joint further protect the sealed environment inside the furnace. When furnace chamber adjustment operations are required, the presence of lubricating oil makes the sliding of the upper furnace body 12 and the No. 3 filling pad 42 smoother, reducing the resistance caused by friction and ensuring the smooth progress of the furnace chamber extension and shortening process. In addition, the design of the heat insulation pad 61 can also insulate the lubricating oil in the cavity, preventing the lubricating oil from deteriorating due to the high temperature inside the furnace and ensuring that the lubricating oil always maintains good lubrication performance. The annular cross-sectional shape of the heat insulation pad 61 fits tightly against the outer wall of the lower furnace body 1, effectively blocking the direct transfer of heat and providing a relatively stable working environment for the lubricating oil. This sealing auxiliary structure that combines oil seal and heat insulation design not only improves the sealing effect of the single crystal furnace, but also further enhances the stability and reliability of the single crystal furnace operation by reducing component wear and the intrusion of external impurities, creating more favorable conditions for the high-quality growth of single crystals.

[0030] The sliding plate 53 is provided with oil guide grooves 7, and there are three oil guide grooves 7. One side opening of the oil guide groove 7 is close to the outer wall of the lower furnace body 1. When lubricating oil accumulates in the cavity formed between the lower furnace body 1 and the upper furnace body 12, some lubricating oil seeps into the three oil guide grooves 7, so that some lubricating oil lubricates the outer wall of the lower furnace body 1. This design further optimizes the lubrication effect, ensures the smoothness of the outer wall of the lower furnace body 1 during the sliding process of the upper furnace body 12, and reduces energy loss and component wear caused by friction. At the same time, the setting of one side opening of the oil guide groove 7 close to the outer wall of the lower furnace body 1 allows the lubricating oil to act more directly on the contact surface, improving the efficiency and uniformity of lubrication. In the operation of extending and shortening the furnace chamber, this design ensures that the lubricating oil can continuously and effectively provide lubrication to the components, thereby extending the service life of the equipment.

[0031] A fixing frame 71 is fixedly connected inside the upper furnace body 12, and the fixing frame 71 is located above the upper crucible 18. A water-cooled heat shield 72 is fixedly connected to the inner ring of the fixing frame 71. When the crystal pulling assembly 22 pulls the crystal rod, the fixing frame 71 is fixed above the upper crucible 18, and the water-cooled heat shield 72 is fixed above the center of the upper crucible 18. Circulating cooling water is introduced into the water-cooled heat shield 72 to cool the pulled crystal rod in a timely and effective manner, preventing the crystal rod from deforming or developing internal defects due to excessive temperature during the pulling process. The circulating cooling water flows inside the water-cooled heat shield 72, carrying away the heat conducted from the crystal rod through heat exchange, maintaining the crystal rod within a suitable temperature range for growth and pulling operations. This cooling design is crucial for ensuring the crystal rod... The quality and integrity of the crystal structure are crucial. It can precisely control the temperature gradient of the crystal rod, keeping the cooling rate of each part of the crystal rod relatively consistent during the growth process. This reduces stress concentration and crystal defects caused by uneven temperature. At the same time, the fixed position design of the fixing frame 71 and the water-cooled heat shield 72 ensures that the cooling water can accurately act on the pulled crystal rod, improving cooling efficiency. Moreover, this cooling structure is coordinated with the overall design of the single crystal furnace and will not interfere with other operations and components in the furnace chamber. During the extension and shortening of the furnace chamber, the fixing frame 71 and the water-cooled heat shield 72 move synchronously with the movement of the upper furnace body 12, always maintaining effective cooling of the crystal rod, providing a reliable temperature control guarantee for the high-quality growth of single crystals.

[0032] A water guide pipe 8 is fixedly connected to the outer wall of the upper furnace body 12; a diversion groove 81 is provided inside the upper furnace body 12 near the water guide pipe 8, and the diversion groove 81 has two outlets; a circular hole groove 82 is provided inside the fixing frame 71, one end of the circular hole groove 82 can be connected to one outlet of the diversion groove 81, and the other end of the circular hole groove 82 is connected to the water-cooled heat shield 72; a guide groove 83 is provided inside the upper furnace body 12, the guide groove 83 is spiral in shape, and the guide groove 83 can be connected to the other outlet of the diversion groove 81; a drain pipe 84 is fixedly connected to the outer wall of the upper furnace body 12, and the drain pipe 84 is connected to the end of the guide groove 83 away from the diversion groove 81; when cooling water is introduced into the water-cooled heat shield 72, an external water pump pumps cooling water into the interior of the water guide pipe 8, and the cooling water flows into the diversion groove 81 for diversion, the outlet diameter of the diversion groove 81 near the water-cooled heat shield 72 is larger than that of the diversion groove 81 near the guide groove 81. The outlet diameter of the flow channel 83 allows most of the cooling water to be sent into the water-cooled heat shield 72 through the circular hole channel 82 to cool the crystal rod. A portion of the cooling water flows downwards into the interior of the guide channel 83 in a spiral pattern, cooling the cavity between the lower furnace body 1 and the upper furnace body 12. This ensures that the working environment temperature of each sealing component is not too high, thus maintaining the stability of the sealing component performance and avoiding the problem of accelerated aging and decreased sealing effect caused by high temperature. The cooling water flowing out of the guide channel 83 is finally discharged from the single crystal furnace through the drain pipe 84, completing a cooling cycle. This split cooling water design ensures effective cooling during the crystal rod pulling process while also taking into account the temperature control of key sealing parts inside the furnace. This refined cooling water design, closely integrated with the overall sealing and furnace chamber adjustment structure of the single crystal furnace, provides comprehensive temperature protection for the stable operation of the single crystal furnace under complex process conditions, further improving the quality and consistency of single crystal growth.

[0033] Working process: In the application of a high-sealing single crystal furnace with an extended furnace chamber, the lower furnace body 1 serves as the main furnace chamber, the furnace base 11 is supported below the lower furnace body 1, and the upper furnace body 12 slides against the outer wall of the lower furnace body 1 as an extended furnace chamber. The bracket 16 is fixed at the center inside the lower furnace body 1, supporting the lower crucible 17, which is the main crucible. The upper crucible 18 slides against the outer wall of the lower crucible 17 as an extended crucible. When adjusting the high-sealing single crystal furnace to extend the furnace chamber, the output end of the hydraulic cylinder 13 drives the first top plate 14 to slide upward, supporting the first top plate 14 at the bottom of the upper furnace body 12. The top plate 14 is pushed upwards, causing the upper furnace body 12 to slide against the outer wall of the lower furnace body 1, extending the furnace chamber. The top plate 14 can seal the connection between the upper furnace body 12 and the lower furnace body 1. At the same time, the upper furnace body 12, under its own weight, drives the upper crucible 18, supported by multiple lifting blocks 15, to slide down against the outer wall of the lower crucible 17, extending the crucible. When it is necessary to shorten the furnace chamber, the output end of the hydraulic cylinder 13 is controlled to drive the top plate 14 downwards, causing the upper furnace body 12 to slide down against the outer wall of the lower furnace body 1, shortening the furnace chamber. At the same time, the upper furnace body 12 drives the upper crucible 18, supported by multiple lifting blocks 15, to slide down against the outer wall of the lower furnace body 1, shortening the furnace chamber. Crucible 18 slides down onto the outer wall of lower crucible 17 under gravity, completing the shortening operation of the crucible. The lower furnace body 1 and upper furnace body 12, as well as the lower crucible 17 and upper crucible 18, move in close contact. Vacuum technology is used inside the furnace. This close-fitting design between components in the vacuum environment effectively prevents the intrusion of external gases, ensuring the purity of the single crystal growth environment, and greatly improves the sealing performance of the furnace. This highly airtight structure is crucial for maintaining a constant temperature and pressure field inside the furnace, helping to reduce impurity incorporation during single crystal growth and improving the quality and purity of the single crystal. Furthermore, the application of vacuum technology promotes the uniform distribution of heat, enabling the single crystal to undergo more balanced heat treatment during growth, further optimizing the crystal structure of the single crystal. The entire process ensures the stability and sealing of the single crystal furnace during the adjustment of the furnace chamber length, effectively improving the flexibility and applicability of the single crystal furnace. It can better meet the requirements of the single crystal furnace chamber length under different process conditions. As the furnace chamber is extended, the longitudinal temperature gradient from the melt surface to the upper part of the furnace chamber becomes more stable, which makes the crystal growth more stable and reduces the probability of dislocation multiplication and crystal cracking.When extending the furnace chamber and crucible, two support frames 9 are fixed to the furnace base 11 and located on both sides of the lower furnace body 1 as supports. During the sliding of the first top plate 14 at the output end of the hydraulic cylinder 13, the first top plate 14 slides synchronously on the two support frames 9, and the first top plate 14 can press the inclined surface of the trapezoidal limiting block 91, so that the limiting block 91 presses the second elastic element into the interior of the support frame 9. After the first top plate 14 passes the limiting block 91, the second elastic element pushes the limiting block 91 out, and the upper surface of the trapezoidal limiting block 91 supports the furnace. At the bottom of the first top plate 14, the output end of the hydraulic cylinder 13 still provides the main support for the first top plate 14, while the limiting block 91 provides stable auxiliary support for the first top plate 14, ensuring the stability of the upper furnace body 12 and the upper crucible 18 after rising, making the furnace chamber extension operation more reliable. The second elastic element is set as a spring, and when the limiting block 91 is pushed out by the elastic force of the second elastic element, most of the limiting block 91 is still located inside the support frame 9. At the same time, each time the first top plate 14 slides between two limiting blocks 91 in a set, it is adjusted. A set height can be adaptively adjusted according to the required extension height of the furnace chamber. When the output end of the hydraulic cylinder 13 drives the first top plate 14 to slide down, the upper surface of the trapezoidal limit block 91 needs to be manually pressed. The limit block 91 retracts into the support frame 9. After the first top plate 14 passes the limit block 91, the second elastic element pushes the limit block 91 out again, preparing for the next rise of the first top plate 14. This design enhances the stability of the entire extended furnace chamber structure and further improves the efficiency while ensuring the flexible realization of the furnace chamber extension and shortening functions. The high-sealing single crystal furnace provides a solid equipment guarantee for the high-quality growth of single crystals due to its reliability and safety during operation. At the same time, when the No. 1 top plate 14 is located on the upper plane of the two limiting blocks 91, since the width of the No. 1 top plate 14 is greater than the distance between the two limiting blocks 91, part of the limiting blocks 91 are still pressed between the support frame 9 and the inner wall of the No. 1 top plate 14. The limiting blocks 91 are squeezed by the No. 2 elastic element, so that one end of the limiting block 91 is pressed against the inner wall of the No. 1 top plate 14, which plays a role in auxiliary support and limiting of the No. 1 top plate 14. When the crystal growth furnace chamber is extended, the position of the crystal pulling furnace chamber also needs to be raised. The lifting frame 21 slides inside the fixed base 2 as the extension position, and the crystal pulling assembly 22 is used to enter the crystal pulling furnace chamber inside the crystal growth furnace chamber. The output end of the hydraulic cylinder 13 drives the first top plate 14 to slide upward to extend the crystal growth furnace chamber. The first top plate 14 simultaneously drives the lifting frame 21 connected to the second top plate 23 and the crystal pulling furnace chamber to slide upward. The lifting frame 21 slides on the inner wall of the fixed base 2 to realize the position adaptation and lifting of the crystal pulling furnace chamber. When the furnace chamber is shortened, the output end of the hydraulic cylinder 13 is controlled to drive the first top plate 14 to slide downward. The first top plate 14 drives the lifting frame 21 connected to the second top plate 23 and the crystal pulling furnace chamber to slide downward synchronously, so that the crystal pulling furnace chamber returns to the appropriate position. This synchronous adjustment design ensures the coordination between the crystal growth furnace chamber and the crystal pulling furnace chamber during the furnace chamber length adjustment process, avoids the operation problems caused by the mismatch between the two positions, and further improves the stability and reliability of the single crystal furnace operation. When the silicon material is heated in the crucible, a heater 3 is installed inside the lower furnace body 1 and located below the lower crucible 17 to heat and melt the silicon material in the lower crucible 17. Multiple stacked annular No. 1 filling pads 31 are filled in the filling groove of the No. 1 top plate 14. The material of the No. 1 filling pads 31 is ceramic fiber composite material, which has excellent high temperature resistance and heat insulation effect. Multiple No. 1 filling pads 31 can fit tightly against the connection between the upper furnace body 12 and the lower furnace body 1 to seal the connection. During the extension and shortening of the furnace chamber, as the No. 1 top plate 14 moves up and down, the No. 1 filling pads 31 always maintain a tight fit with the connection between the upper furnace body 12 and the lower furnace body 1, effectively preventing heat loss and external gas intrusion, and further enhancing the sealing performance of the furnace body. At the same time, the stacked installation design of the No. 1 filling pads 31 allows them to adaptively adjust according to the actual gap at the connection between the upper furnace body 12 and the lower furnace body 1, ensuring the stability and reliability of the sealing effect. When sealing the connection between the lower furnace body 1 and the upper furnace body 12, a fixing plate 4 is used to fix the lower furnace body 1 at the angle of the protruding part. Multiple stacked annular No. 2 filling pads 41 are attached between the fixing plate 4 and the inner wall of the upper furnace body 12. These, along with annular No. 3 filling pads 42, are fixed to the bottom inner wall of the upper furnace body 12 and attached to the outer wall of the lower furnace body 1. The expanded graphite No. 2 filling pads 41 and No. 3 filling pads 42 have excellent high-temperature resistance and sealing performance. When the furnace temperature rises, the No. 2 filling pads 41 and No. 3 filling pads 42 will expand and fit more tightly at the connection, forming a reliable sealing barrier that effectively prevents gas leakage from the furnace and outside air leakage. The entry of expanded graphite material further ensures the stability and purity of the single crystal growth environment inside the furnace. This sealing design not only meets the sealing requirements of the single crystal furnace under high-temperature operating conditions, but also maintains a long-term sealing effect due to its good elasticity and adaptability, reducing the sealing failure caused by aging and deformation of the seals. Meanwhile, the stacked design of the second-level filling pad 41 enhances the redundancy of the sealing structure. Even if some of the second-level filling pads 41 are damaged or worn, the others can still continue to perform their sealing function, ensuring the reliability and safety of the single crystal furnace's long-term operation. Furthermore, the ring of the second-level filling pad 41 and the third-level filling pad 42... The cross-sectional shape matches the shape of the connection between the lower furnace body 1 and the upper furnace body 12, making the seal more fitted and uniform, further improving the sealing effect. This refined sealing design provides a strong guarantee for the stable operation of the single crystal furnace under harsh working conditions such as high temperature and high pressure. When the second filling pad 41 and the third filling pad 42 seal the connection between the lower furnace body 1 and the upper furnace body 12, the ring plate and the sliding plate 53 on the sliding rod 51 are respectively attached to the surface of the second filling pad 41 and the third filling pad 42. As the furnace chamber extends, the upper furnace body 12 slides upward, which can squeeze the sliding rod 51 into the interior of the fixed cylinder 5. The first elastic element 52 contracts and is subjected to force, so that the bottom of the fixed cylinder 5... The sliding plate 53 of the part, together with the ring plate on the sliding rod 51, further squeezes the No. 3 filling pad 42 and the No. 2 filling pad 41, thereby improving the tightness of the seal. When the furnace chamber shortens, the upper furnace body 12 slides down under its own weight, and the No. 1 elastic element 52 also extends accordingly. During this process, the sliding rod 51 and its ring plate always keep in close contact with the No. 2 filling pad 41, and the sliding plate 53 and the surface of the No. 3 filling pad 42 also continuously abut against each other, ensuring the continuity and stability of the sealing structure. At the same time, the design of the fixed cylinder 5 also takes into account the thermal expansion factor. The sliding design of the sliding rod 51 in the fixed cylinder 5 reserves enough thermal expansion space to avoid sealing failure caused by thermal expansion and contraction. When the No. 3 filling pad 42 seals the connection between the lower furnace body 1 and the upper furnace body 12, the oil pipe 6 is first opened, and lubricating oil is injected into the oil pipe 6. The lubricating oil then enters the cavity formed between the lower furnace body 1 and the upper furnace body 12 and accumulates on the No. 3 filling pad 42. Subsequently, the oil pipe 6 is sealed, and a small amount of lubricating oil accumulates on the No. 3 filling pad 42. This not only provides an oil seal at the connection between the lower furnace body 1 and the upper furnace body 12 but also lubricates the outer wall of the lower furnace body 1, reducing friction when the upper furnace body 12 and the No. 3 filling pad 42 slide upwards. This design effectively reduces wear between components and extends the service life of the equipment. At the same time, the oil film formed by the lubricating oil can also prevent external impurities from entering the connection to a certain extent, further protecting the sealing environment inside the furnace. When furnace chamber adjustment operations are required... At the same time, the presence of lubricating oil makes the sliding of the upper furnace body 12 and the No. 3 filling pad 42 smoother, reducing the resistance caused by friction and ensuring the smooth progress of the furnace chamber extension and shortening process. In addition, the design of the heat insulation pad 61 can also insulate the lubricating oil in the cavity, prevent the lubricating oil from deteriorating due to the high temperature inside the furnace, and ensure that the lubricating oil always maintains good lubrication performance. The annular cross-sectional shape of the heat insulation pad 61 fits tightly against the outer wall of the lower furnace body 1, effectively blocking the direct transfer of heat and providing a relatively stable working environment for the lubricating oil. This sealing auxiliary structure that combines oil seal and heat insulation design not only improves the sealing effect of the single crystal furnace, but also further enhances the stability and reliability of the single crystal furnace operation by reducing component wear and the intrusion of external impurities, creating more favorable conditions for the high-quality growth of single crystals. When lubricating oil accumulates in the cavity formed between the lower furnace body 1 and the upper furnace body 12, some of the lubricating oil seeps into the three oil guide grooves 7, allowing some of the lubricating oil to lubricate the outer wall of the lower furnace body 1. This design further optimizes the lubrication effect, ensuring the smoothness of the outer wall of the lower furnace body 1 during the sliding process of the upper furnace body 12, reducing energy loss and component wear caused by friction. At the same time, the setting of one side opening of the oil guide groove 7 close to the outer wall of the lower furnace body 1 allows the lubricating oil to act more directly on the contact surface, improving the efficiency and uniformity of lubrication. In the operation of extending and shortening the furnace chamber, this design ensures that the lubricating oil can continuously and effectively provide lubrication to the components, thereby extending the service life of the equipment. When the crystal pulling assembly 22 pulls the crystal rod, it is fixed above the upper crucible 18 by the fixing bracket 71, and the water-cooled heat shield 72 is fixed above the center of the upper crucible 18. Circulating cooling water is introduced into the water-cooled heat shield 72, which can cool the pulled crystal rod in a timely and effective manner, preventing the crystal rod from being damaged by temperature during the pulling process. Excessive heat can cause deformation and internal defects. Circulating cooling water flows within the water-cooled heat shield 72, carrying away the heat conducted from the crystal rod through heat exchange. This maintains the crystal rod within a suitable temperature range for growth and pulling operations. This cooling design is crucial for ensuring the quality of the crystal rod and the integrity of the crystal structure. It can precisely control the temperature gradient of the crystal rod, keeping the cooling rate of each part of the crystal rod relatively consistent during growth, reducing stress concentration and crystal defects caused by uneven temperature. At the same time, the fixed position design of the fixing frame 71 and the water-cooled heat shield 72 ensures that the cooling water can accurately act on the pulled crystal rod, improving cooling efficiency. Moreover, this cooling structure is coordinated with the overall design of the single crystal furnace and will not interfere with other operations and components in the furnace chamber. During the extension and shortening of the furnace chamber, the fixing frame 71 and the water-cooled heat shield 72 move synchronously with the movement of the upper furnace body 12, always maintaining effective cooling of the crystal rod, providing reliable temperature control for high-quality growth of single crystals.When cooling water is introduced into the water-cooled heat shield 72, an external water pump pumps the cooling water into the water guide pipe 8. The cooling water flows into the diversion channel 81 for diversion. The outlet diameter of the diversion channel 81 near the water-cooled heat shield 72 is larger than the outlet diameter of the diversion channel 81 near the guide channel 83. Therefore, most of the cooling water is sent into the water-cooled heat shield 72 through the circular slot 82 to cool the crystal rod. The remaining cooling water flows down into the guide channel 83 in a spiral flow to cool the cavity between the lower furnace body 1 and the upper furnace body 12, ensuring that the working environment temperature of each seal does not become too high, thereby maintaining the performance of the seal. To ensure stable cooling and prevent accelerated aging and reduced sealing performance of seals due to high temperatures, the cooling water flowing from the guide channel 83 is ultimately discharged outside the single crystal furnace via the drain pipe 84, completing a cooling cycle. This split-flow cooling water design ensures effective cooling during the crystal rod pulling process while also taking into account temperature control of key sealing components within the furnace. This refined cooling water design, closely integrated with the overall sealing and furnace chamber regulation structure of the single crystal furnace, provides comprehensive temperature protection for the stable operation of the single crystal furnace under complex process conditions, further improving the quality and consistency of single crystal growth.

[0034] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A highly airtight single crystal furnace with an extended furnace chamber, characterized in that: The furnace includes a lower furnace body; a furnace base is fixedly connected to the bottom end of the lower furnace body; an upper furnace body is slidably connected to the lower furnace body; a hydraulic cylinder is fixedly connected to the furnace base; a No. 1 top plate is fixedly connected to the output end of the hydraulic cylinder, the No. 1 top plate is located at the bottom of the upper furnace body, and the No. 1 top plate is slidably connected to the outer wall of the lower furnace body; multiple lifting blocks are fixedly connected to the inner wall of the upper furnace body; a bracket is fixedly connected to the center of the lower furnace body; a lower crucible is fixedly connected to the bracket; an upper crucible is slidably connected to the outer wall of the lower crucible, and the upper crucible is attached to the multiple lifting blocks.

2. A highly airtight single crystal furnace with an extended furnace chamber according to claim 1, characterized in that: Two support frames are fixedly connected to each other on the furnace base, and the No. 1 top plate is slidably connected to the outer wall of the support frame; the inner wall of the support frame is slidably connected to multiple limiting blocks through the No. 2 elastic element, and the cross-sectional shape of the limiting blocks is trapezoidal.

3. A highly airtight single crystal furnace with an extended furnace chamber according to claim 1, characterized in that: A fixed seat is fixedly connected to the furnace base; a lifting frame is slidably connected to the inner wall of the fixed seat; a crystal pulling assembly is fixedly connected to the lifting frame; a second top plate is fixedly connected to the outer wall of the first top plate near the lifting frame, and the second top plate is fixedly connected to the lifting frame.

4. A highly airtight single crystal furnace with an extended furnace chamber according to claim 1, characterized in that: A heater is fixedly connected to the bottom of the lower furnace body; a filling groove is opened on the No. 1 top plate near the lower part of the upper furnace body, and multiple No. 1 filling pads are fixedly connected in the filling groove. The multiple No. 1 filling pads are stacked and installed. The cross-sectional shape of the No. 1 filling pad is annular, and the material of the No. 1 filling pad is ceramic fiber composite material.

5. A highly airtight single crystal furnace with an extended furnace chamber according to claim 1, characterized in that: A fixing plate is fixed to the top outer wall of the lower furnace body; multiple No. 2 filling pads are fixed between the fixing plate and the outer wall of the lower furnace body, and the multiple No. 2 filling pads are stacked; a No. 3 filling pad is fixed to the bottom inner wall of the upper furnace body; the cross-sectional shape of the No. 2 filling pad and the No. 3 filling pad are both annular, and the material of the No. 2 filling pad and the No. 3 filling pad is expanded graphite.

6. A highly airtight single crystal furnace with an extended furnace chamber according to claim 5, characterized in that: A sliding plate is slidably connected to the outer wall of the lower furnace body near the top of the No. 3 filling pad; a fixed cylinder is fixedly connected to the sliding plate; a sliding rod is slidably connected to the inner wall of the fixed cylinder, the sliding rod passes through the fixed plate and is supported below the No. 2 filling pad, and a ring plate is fixedly connected to the sliding rod, and the ring plate is located between the sliding rod and the No. 2 filling pad; a No. 1 elastic element is fixedly connected inside the fixed cylinder.

7. A highly airtight single crystal furnace with an extended furnace chamber according to claim 5, characterized in that: An oil pipe is fixedly connected to the interior of the upper furnace body near the fixed plate; a heat insulation pad is fixedly connected to the outer wall of the lower furnace body near the oil pipe, and the heat insulation pad has a ring-shaped cross-section.

8. A highly airtight single crystal furnace with an extended furnace chamber according to claim 6, characterized in that: The sliding plate is provided with oil guide grooves, and there are three oil guide grooves. One side opening of the oil guide groove is close to the outer wall of the lower furnace body.

9. A highly airtight single crystal furnace with an extended furnace chamber according to claim 1, characterized in that: A fixing frame is fixed inside the upper furnace body, and the fixing frame is located above the upper crucible; a water-cooled heat shield is fixed to the inner ring of the fixing frame.

10. A highly airtight single crystal furnace with an extended furnace chamber according to claim 9, characterized in that: A water guide pipe is fixedly connected to the outer wall of the upper furnace body; a diversion channel is provided inside the upper furnace body near the water guide pipe, and the diversion channel has two outlets; a circular slot is provided inside the fixing frame, one end of which can be connected to one outlet of the diversion channel, and the other end of which is connected to the water-cooled heat shield; a spiral guide channel is provided inside the upper furnace body, and the guide channel can be connected to the other outlet of the diversion channel; a drain pipe is fixedly connected to the outer wall of the upper furnace body, and the drain pipe is connected to the end of the guide channel away from the diversion channel.

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