Silicon liquid guiding device for lower cavity of single crystal furnace

Abstract

The invention provides a single crystal furnace lower cavity silicon liquid flow guide device which comprises a device body, and the device body comprises a first flow guide pipe, a first packaging heater, a first fixed mounting plate, a second flow guide pipe, a second fixed mounting plate, a second packaging heater, a third flow guide pipe, a double-layer crucible and a cavity. The first packaging heater and the second packaging heater are packaging heaters of the same structure, each packaging heater comprises a packaging heating unit, an electromagnetic induction coil heating assembly and a sealing assembly, each packaging heating unit is composed of a high-purity graphite core body, a graphite sealing sleeve and flexible graphite paper, and the graphite core bodies are assembled in an inner cavity of the graphite sealing sleeve; graphite paper is laid on the upper end face and the lower end face of the core body to eliminate working gaps and prevent thermal-state looseness, then sealing baffles are welded to the axial and radial joint faces of the graphite paper and the sealing sleeve through the high-temperature welding technology, and an airtight packaging structure is formed; the electromagnetic induction coil heating assembly is composed of a coil end and a coil water passing end.

Description

Technical Field

[0001] This invention relates to the field of single crystal furnaces, and more specifically to a silicon liquid guiding device for the lower cavity of a single crystal furnace. Background Technology

[0002] In the current lower chamber structure of a single-crystal furnace's secondary feeding device, the feeding system typically uses a straight-through feeding pipe that extends directly to the lower crucible. During actual operation, as the molten silicon formed from the melting of the silicon rod in the upper chamber flows through the feeding pipe, temperature gradient changes due to heat loss from the pipe wall cause localized solidification of the high-temperature silicon at the transport cross-section, forming a silicon crystal deposition layer on the inner surface of the pipe wall. This indirect deposition effect accumulates over time, leading to a reduction in the flow channel cross-sectional area, ultimately causing blockage of the feeding pipe and significantly reducing silicon molten metal transport efficiency and process stability. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention provides a silicon liquid guiding device for the lower cavity of a single crystal furnace, so as to solve at least one of the above-mentioned technical problems.

[0004] The technical solution of this invention is: a silicon liquid guiding device for the lower cavity of a single crystal furnace, comprising a device body, characterized in that the device body includes a first guiding pipe, a first encapsulation heater, a first fixed mounting plate, a second guiding pipe, a second fixed mounting plate, a second encapsulation heater, a third guiding pipe, a double-layer crucible, and a cavity; the first encapsulation heater and the second encapsulation heater are both encapsulation heaters with identical structures; the encapsulation heater includes an encapsulation heating unit, an electromagnetic induction coil heating assembly, and a sealing assembly.

[0005] The encapsulation heating unit consists of a high-purity graphite core, a graphite sleeve, and flexible graphite paper. The graphite core is assembled into the inner cavity of the graphite sleeve. Graphite paper is laid on the upper and lower end faces of the core to eliminate working gaps and prevent loosening under heat. Then, a high-temperature welding process is used to weld sealing baffles on the axial and radial joint surfaces of the graphite paper and the sleeve to form an airtight encapsulation structure.

[0006] The electromagnetic induction coil heating assembly consists of two parts: the coil end and the coil water-passing end. The coil end consists of a coil, a coil frame, an adjusting block, and screws. After the heating unit is assembled, the electromagnetic coil is fitted onto the outer wall of the graphite sleeve, ensuring that it is coaxially positioned with the sleeve. Several threaded bosses are provided on the outside of the coil. The mounting holes of the coil frame are axially assembled with the bosses, and the anti-loosening nuts are tightened to the specified torque.

[0007] This invention establishes a dynamic temperature compensation mechanism along the silicon molten material flow path by integrating a temperature-controlled heating coil module. This scheme effectively suppresses unexpected solidification of the silicon molten material during transport, ensuring stable flow characteristics of the melt above the solid-liquid phase transition point, thereby guaranteeing the continuity and reliability of the secondary feeding process. When a high-frequency alternating current passes through the external excitation coil, a strong eddy current field is generated within the graphite core. Utilizing the properties of graphite, electrical energy is converted into heat energy, rapidly raising the core temperature to above 1450°C. The generated thermal radiation effectively maintains the uniformity of the temperature field on the inner wall of the enclosure, ensuring that the molten silicon flowing through the inner wall is always above its solidification point (1414°C), thus avoiding silicon phase transition precipitation and nodule formation on the inner wall. This encapsulation structure not only ensures electromagnetic-thermal conversion efficiency but also ensures structural stability under high-temperature conditions through the self-sealing design of multi-layer graphite materials, creating favorable conditions for silicon molten material transport.

[0008] Further preferably, the inner wall of the lead-out end of the coil is provided with a groove for placing a sealing ring, and the end face of the copper electrode rod-shaped end is provided with a groove for placing a sealing ring. After the copper electrode rod-shaped end is inserted into the hole of the lead-out end of the coil, it is sealed by the sealing ring. The inner wall of the sealing flange is provided with a groove for placing a sealing ring. After the copper electrode is inserted into the hole of the sealing flange, it is sealed by the sealing ring.

[0009] Since this single crystal furnace is a high-vacuum sealed structure, the entire coil heating structure must not affect the sealing performance of the cavity. The coil and its supporting structure must be sealed in a space that is in communication with the cavity.

[0010] In a further preferred embodiment, the two mounting holes at the upper end of the adjusting block are aligned with the machined through holes on the bottom plate of the graphite sleeve, and are then fixed in place by screws.

[0011] Ensure the overall structural rigidity and assembly stability.

[0012] Further preferably, the water-conducting end of the coil consists of a copper electrode, a ceramic sleeve, a sealing flange, a flange, a copper sealing gasket, a lock nut, a copper washer, a water pipe connector, an electrode clamp, a fireproof cover, an electrode clamp, and a connecting guide plate. After the coil end is assembled, the rod-shaped ends of the two copper electrodes are aligned with the reserved holes at the coil lead-out end and inserted. The electrode clamp mechanism is used for radial fixation. Then, the other end of the copper electrode is precisely aligned with the mounting hole of the flange and inserted. The ceramic sleeve, the sealing flange, and the copper sealing gasket are assembled in sequence. The bottom end of the flange has a positioning stop, and the ceramic sleeve fits tightly with it. The upper end of the flange has a flange structure, which is fitted with the sealing flange, and a copper sealing gasket is placed on it.

[0013] This ensured a tight seal after connection.

[0014] In a further preferred embodiment, the flange portion of the flange is provided with threaded holes, and the copper gasket and the sealing flange are provided with through holes at corresponding positions. High-strength screws are used to achieve a fastening connection between the three. The flange is provided with a threaded cylindrical platform, and the fireproof cover is fixed to the flange by screws.

[0015] In a further preferred embodiment, the protruding end of the copper electrode is machined with an external thread, and its position is above the plane of the copper sealing gasket. Then, the locking nut, copper washer, connecting guide plate, copper washer and locking screw are installed in sequence. The top hole of the copper electrode is provided with an internal thread, and the internal water circulation cooling of the coil is realized by connecting a water pipe connector.

[0016] Further optimization involves adding an electrode clamp between the two sets of connecting guide plates to ensure insulation requirements are met and to prevent short circuits between electrodes.

[0017] Further preferably, the end face of the first fixed mounting plate is provided with 6 threaded holes. The adjusting block in the first encapsulation heater is fixedly connected to the first fixed mounting plate by screws through the through hole of the bottom plate of the intermediate encapsulation heating unit. The first encapsulation heater is horizontally placed into the cavity along the waist-shaped opening on the side of the cavity. The external thread at the bottom of the first guide tube is coaxially aligned with the central threaded hole of the first fixed mounting plate and inserted axially. The upper circular end cap of the first guide tube is rotated using a tooling clamp to form a rigid threaded connection between the first guide tube and the first fixed mounting plate.

[0018] The upper cover of the second encapsulated heater has four threaded holes. The second guide tube is fixedly connected by screws through the through hole of the middle second fixed mounting plate. A circular disk is welded to the bottom of the second encapsulated heater. The third guide tube is fixedly connected to the through hole on the circular disk by bolts.

[0019] The connection method has been optimized, the device has a compact structure, and operates smoothly.

[0020] Beneficial effects:

[0021] 1. Through the cooperation of three core modules, the electromagnetic induction coil heats the graphite, ensuring the sealing performance of the encapsulation heater and the cavity in the vacuum cavity, so as to achieve a continuous and stable flow of molten silicon into the crucible.

[0022] 2. Design a compact temperature compensation system: Integrate a high-efficiency heat source and a dynamic temperature control module within a limited space to ensure that the molten silicon in the upper furnace cover maintains a temperature above the liquidus line and avoids local solidification caused by heat loss;

[0023] 3. Achieve a modular structure for rapid deployment: Develop lightweight heating components that couple with existing furnace bodies through standardized interfaces, simplifying the installation process while ensuring temperature field uniformity to meet the process requirements of continuous silicon melt flow to the crucible. Attached Figure Description

[0024] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0025] Figure 2 This is a schematic diagram of the structure of the encapsulated heating unit of the present invention;

[0026] Figure 3 This is a schematic diagram of the electromagnetic induction coil heating assembly structure of the present invention;

[0027] Figure 4 This is a schematic diagram of the structure of the coil end of the present invention;

[0028] Figure 5 This is a schematic diagram of the water-passing end structure of the coil of the present invention;

[0029] Figure 6 This is a cross-sectional view of the water-passing end of the coil of the present invention;

[0030] Figure 7 This is a schematic diagram of the sealing assembly of the present invention;

[0031] Figure 8 This is a partially enlarged view of the sealing component of the present invention.

[0032] In the diagram: 1. First guide tube; 2. First encapsulated heater; 3. First fixed mounting plate; 4. Second guide tube; 5. Second fixed mounting plate; 6. Second encapsulated heater; 7. Third guide tube; 8. Double-layer crucible; 9. Cavity; 10. Graphite core; 11. Graphite sleeve; 12. Flexible graphite paper; 13. Coil; 14. Coil frame; 15. Adjusting block; 16. Copper electrode; 17. Ceramic sleeve; 18. Sealing flange; 19. Flange; 20. Copper sealing gasket; 21. Locking nut; 22. Copper washer; 23. Water pipe connector; 24. Electrode clamp; 25. Fireproof cover; 26. Electrode clamp; 27. Connecting guide plate; 28. Coil end; 29. ​​Coil water supply end. Detailed Implementation

[0033] The present invention will now be further described with reference to the accompanying drawings.

[0034] Reference Figures 1-8 As shown, a silicon liquid guiding device for the lower cavity of a single crystal furnace includes a main body, which comprises a first guiding pipe 1, a first encapsulation heater 2, a first fixed mounting plate 3, a second guiding pipe 4, a second fixed mounting plate 5, a second encapsulation heater 6, a third guiding pipe 7, a double-layer crucible 8, and a cavity 9. The first and second encapsulation heaters are both encapsulation heaters with identical structures. Each encapsulation heater includes an encapsulation heating unit, an electromagnetic induction coil heating assembly, and a sealing assembly.

[0035] The encapsulation heating unit consists of a high-purity graphite core 10, a graphite sleeve 11, and flexible graphite paper 12. The graphite core is assembled into the inner cavity of the graphite sleeve. Graphite paper is laid on the upper and lower end faces of the core to eliminate working gaps and prevent loosening under heat. Then, a high-temperature welding process is used to weld sealing baffles on the axial and radial joint surfaces of the graphite paper and the sleeve to form an airtight encapsulation structure.

[0036] The electromagnetic induction coil heating assembly consists of two parts: the coil end 28 and the coil water-passing end 29. The coil end consists of the coil 13, the coil frame 14, the adjusting block 15, and the screw. After the heating unit is assembled, the electromagnetic coil is fitted onto the outer wall of the graphite sleeve, ensuring that it is coaxially positioned with the sleeve. Several threaded bosses are provided on the outside of the coil. The mounting holes of the coil frame are axially assembled with the bosses, and the anti-loosening nuts are tightened to the specified torque.

[0037] This invention establishes a dynamic temperature compensation mechanism along the silicon molten material flow path by integrating a temperature-controlled heating coil module. This scheme effectively suppresses unexpected solidification of the silicon molten material during transport, ensuring stable flow characteristics of the melt above the solid-liquid phase transition point, thereby guaranteeing the continuity and reliability of the secondary feeding process. When a high-frequency alternating current passes through the external excitation coil, a strong eddy current field is generated within the graphite core. Utilizing the properties of graphite, electrical energy is converted into heat energy, rapidly raising the core temperature to above 1450°C. The generated thermal radiation effectively maintains the uniformity of the temperature field on the inner wall of the enclosure, ensuring that the molten silicon flowing through the inner wall is always above its solidification point (1414°C), thus avoiding silicon phase transition precipitation and nodule formation on the inner wall. This encapsulation structure not only ensures electromagnetic-thermal conversion efficiency but also ensures structural stability under high-temperature conditions through the self-sealing design of multi-layer graphite materials, creating favorable conditions for silicon molten material transport.

[0038] Further preferred, the inner wall of the coil lead-out end is provided with a groove for placing a sealing ring, and the end face of the copper electrode rod-shaped end is provided with a groove for placing a sealing ring. After the copper electrode rod-shaped end is inserted into the hole of the coil lead-out end, it is sealed by the sealing ring. The inner wall of the sealing flange is provided with a groove for placing a sealing ring. After the copper electrode is inserted into the hole of the sealing flange, it is sealed by the sealing ring.

[0039] Since this single crystal furnace is a high-vacuum sealed structure, the entire coil heating structure must not affect the sealing performance of the cavity. The coil and its supporting structure must be sealed in a space that is in communication with the cavity.

[0040] Further optimization involves aligning the two mounting holes at the upper end of the adjusting block with the machined through holes on the bottom plate of the graphite sleeve, and then securing them a second time with screws.

[0041] Ensure the overall structural rigidity and assembly stability.

[0042] Further optimization shows that the water-conducting end of the coil consists of a copper electrode 16, a ceramic sleeve 17, a sealing flange 18, a flange 19, a copper sealing gasket 20, a lock nut 21, a copper washer 22, a water pipe connector 23, an electrode clamp 24, a fireproof cover 25, an electrode clamp 26, and a connecting guide plate 27. After the coil end is assembled, the rod-shaped ends of the two copper electrodes are aligned with the reserved holes at the coil lead-out end and inserted. The electrode clamp mechanism is used for radial fixation. Then, the other end of the copper electrode is precisely aligned with the mounting hole of the flange and inserted. The ceramic sleeve, the sealing flange, and the copper sealing gasket are assembled in sequence. The bottom of the flange has a positioning stop, and the ceramic sleeve fits tightly with it. The upper part of the flange has a flange structure, which is fitted with the sealing flange, and a copper sealing gasket is placed on it.

[0043] This ensured a tight seal after connection.

[0044] Further optimization involves evenly distributed threaded holes on the flange portion of the flange, through holes at corresponding positions on the copper gasket and sealing flange, and the use of high-strength screws to achieve a tight connection between the three. The flange is equipped with a threaded cylindrical platform, and the fireproof cover is fixed to the flange with screws.

[0045] Further optimization involves machining an external thread on the protruding end of the copper electrode, positioning it above the plane of the copper sealing gasket. Then, the locking nut, copper washer, connecting guide plate, copper washer, and locking screw are installed in sequence. The top hole of the copper electrode is provided with an internal thread, and water circulation cooling inside the coil is achieved by connecting a water pipe connector.

[0046] Further optimization involves adding an electrode clamp between the two sets of connecting guide plates to ensure insulation requirements are met and to prevent short circuits between electrodes.

[0047] Further preferred, the end face of the first fixed mounting plate is provided with 6 threaded holes. The adjusting block in the first encapsulated heater is fixedly connected to the first fixed mounting plate by screws through the through hole of the bottom plate of the intermediate encapsulated heating unit. The first encapsulated heater is horizontally placed into the cavity along the waist-shaped opening on the side of the cavity. The external thread at the bottom of the first guide tube is coaxially aligned with the central threaded hole of the first fixed mounting plate and inserted axially. The upper circular end cap of the first guide tube is rotated using a tooling clamp to form a rigid threaded connection between the first guide tube and the first fixed mounting plate.

[0048] The upper cover of the second encapsulated heater has four threaded holes. The second guide tube is fixedly connected by screws through the through hole of the middle second fixed mounting plate. A circular disk is welded to the bottom of the second encapsulated heater. The third guide tube is fixedly connected to the through hole on the circular disk by bolts.

[0049] The connection method has been optimized, the device has a compact structure, and operates smoothly.

[0050] Beneficial effects:

[0051] 1. Through the cooperation of three core modules, the electromagnetic induction coil heats the graphite, ensuring the sealing performance of the encapsulation heater and the cavity in the vacuum cavity, so as to achieve a continuous and stable flow of molten silicon into the crucible.

[0052] 2. Design a compact temperature compensation system: Integrate a high-efficiency heat source and a dynamic temperature control module within a limited space to ensure that the molten silicon in the upper furnace cover maintains a temperature above the liquidus line and avoids local solidification caused by heat loss;

[0053] 3. Achieve a modular structure for rapid deployment: Develop lightweight heating components that couple with existing furnace bodies through standardized interfaces, simplifying the installation process while ensuring temperature field uniformity to meet the process requirements of continuous silicon melt flow to the crucible.

[0054] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A silicon liquid guiding device for the lower cavity of a single crystal furnace, comprising a main body, characterized in that, The main body of the device includes a first flow guide tube, a first encapsulation heater, a first fixed mounting plate, a second flow guide tube, a second fixed mounting plate, a second encapsulation heater, a third flow guide tube, a double-layer crucible, and a cavity. The first encapsulation heater and the second encapsulation heater are both encapsulation heaters with identical structures. The encapsulation heater includes an encapsulation heating unit, an electromagnetic induction coil heating assembly, and a sealing assembly. The encapsulation heating unit consists of a high-purity graphite core, a graphite sleeve, and flexible graphite paper. The graphite core is assembled into the inner cavity of the graphite sleeve. Graphite paper is laid on the upper and lower end faces of the core to eliminate working gaps and prevent loosening under heat. Then, a high-temperature welding process is used to weld sealing baffles on the axial and radial joint surfaces of the graphite paper and the sleeve to form an airtight encapsulation structure. The electromagnetic induction coil heating assembly consists of two parts: the coil end and the coil water-passing end. The coil end consists of a coil, a coil frame, an adjusting block, and screws. After the heating unit is assembled, the electromagnetic coil is fitted onto the outer wall of the graphite sleeve, ensuring that it is coaxially positioned with the sleeve. Several threaded bosses are provided on the outside of the coil. The mounting holes of the coil frame are axially assembled with the bosses, and the anti-loosening nuts are tightened to the specified torque.

2. The silicon liquid guiding device for the lower cavity of a single crystal furnace according to claim 1, characterized in that, The inner wall of the lead-out end of the coil is provided with a groove for placing a sealing ring, and the end face of the copper electrode rod-shaped end is provided with a groove for placing a sealing ring. After the copper electrode rod-shaped end is inserted into the hole of the lead-out end of the coil, it is sealed by the sealing ring. The inner wall of the sealing flange is provided with a groove for placing a sealing ring. After the copper electrode is inserted into the hole of the sealing flange, it is sealed by the sealing ring.

3. The silicon liquid guiding device for the lower cavity of a single crystal furnace according to claim 1, characterized in that, The two mounting holes at the upper end of the adjusting block are aligned with the machined through holes on the bottom plate of the graphite sleeve, and are then fixed in place by screws.

4. The silicon liquid guiding device for the lower cavity of a single crystal furnace according to claim 1, characterized in that, The water-conducting end of the coil consists of copper electrodes, a ceramic sleeve, a sealing flange, a flange, a copper gasket, a lock nut, a copper washer, a water pipe connector, an electrode clamp, a fireproof cover, an electrode clamp, and a connecting guide plate. After the coil end is assembled, the rod-shaped ends of the two copper electrodes are aligned with the reserved holes at the coil lead-out end and inserted. The electrode clamp mechanism is used for radial fixation. Then, the other end of the copper electrode is precisely aligned with the mounting hole of the flange and inserted. The ceramic sleeve, sealing flange, and copper gasket are assembled in sequence. The bottom of the flange has a positioning stop, and the ceramic sleeve fits tightly with it. The upper part of the flange has a flange structure, which is fitted with the sealing flange, and the copper gasket is placed on it.

5. A silicon liquid guiding device for the lower cavity of a single crystal furnace according to claim 4, characterized in that, The flange portion of the flange is evenly distributed with threaded holes, and the copper sealing gasket and sealing flange are provided with through holes at corresponding positions. High-strength screws are used to achieve a fastening connection between the three. The flange is provided with a threaded cylindrical platform, and the fireproof cover is fixed to the flange by screws.

6. A silicon liquid guiding device for the lower cavity of a single crystal furnace according to claim 4, characterized in that, The copper electrode has an external thread at its top protruding end, and its position is above the plane of the copper sealing gasket. Then, the locking nut, copper washer, connecting guide plate, copper washer and locking screw are installed in sequence. The top hole of the copper electrode has an internal thread, and the internal water circulation cooling of the coil is achieved by connecting a water pipe connector.

7. A silicon liquid guiding device for the lower cavity of a single crystal furnace according to claim 6, characterized in that, An electrode clamp is installed between the two sets of connecting guide plates.

8. The silicon liquid guiding device for the lower cavity of a single crystal furnace according to claim 1, characterized in that, The end face of the first fixed mounting plate is provided with 6 threaded holes. The adjusting block in the first encapsulated heater is fixedly connected to the first fixed mounting plate by screws through the through hole of the bottom plate of the intermediate encapsulated heating unit. The first encapsulated heater is placed into the cavity. The external thread at the bottom of the first guide tube is coaxially aligned with the central threaded hole of the first fixed mounting plate and inserted axially. The upper circular end cap of the first guide tube is rotated using a tooling clamp to form a rigid threaded connection between the first guide tube and the first fixed mounting plate. The upper cover of the second encapsulated heater has four threaded holes. The second guide tube is fixedly connected by screws through the through hole of the middle second fixed mounting plate. A circular disk is welded to the bottom of the second encapsulated heater. The third guide tube is fixedly connected to the through hole on the circular disk by bolts.

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