A material suction tool for a single crystal furnace and a cleaning method thereof

Abstract

This application provides a material suction fixture for a single crystal furnace and its cleaning method, specifically relating to the field of single crystal production technology. The material suction fixture for a single crystal furnace includes an outer liner, an inner liner, and a differential pressure regulating device. The inner liner is nested inside the outer liner and has a tubular section for suctioning material, at least a portion of which extends outside the outer liner. The differential pressure regulating device is connected to the inner liner and is used to regulate the pressure difference between the inner liner and the main chamber of the single crystal furnace. Through the pressure difference between the main chamber of the single crystal furnace and the interior of the inner liner, the bottom material of the crucible is sucked into the inner liner through the tubular section. By combining the nested structure of the outer and inner liners with the differential pressure adsorption process, the problems of low production efficiency, high wear and tear on hot components, and high safety hazards caused by furnace shutdown and cooling are solved. Through dual innovation in structure and process, efficient and non-destructive cleaning of contaminated crucible bottom material is achieved without furnace shutdown, significantly shortening cleaning time and greatly improving the operating efficiency of the single crystal furnace.

Description

Technical Field

[0001] This application relates to the field of single crystal production technology, and in particular to a feeding fixture for a single crystal furnace and its cleaning method. Background Technology

[0002] In the production of monocrystalline silicon, the Czochralski (CZ) method is the mainstream process. This process involves heating and melting high-purity polycrystalline silicon material in a quartz crucible, and then slowly pulling out a monocrystalline silicon rod by lifting a seed crystal.

[0003] In actual production, if the silicon material itself is contaminated, or if secondary contamination occurs between the silicon material and the hot zone components in the furnace during crystal pulling, the molten silicon in the quartz crucible will accumulate a large amount of impurities (such as metallic impurities, oxygen and carbon impurities, etc.). The molten silicon residue left after crystal pulling (referred to as "crucible residue") will carry these impurities. If crystal pulling is directly repeated, impurities will continue to mix into the new molten silicon, not only causing abnormal minority carrier lifetimes in single-crystal silicon, significantly reducing the quality of the crystal rods, or even causing the crystal rods to be scrapped, but also accelerating the corrosion of the inner wall of the quartz crucible, shortening the crucible's service life, and causing serious waste of production costs.

[0004] In existing single-crystal furnace feeding fixtures, the mainstream method for addressing the aforementioned problems is the furnace-opening cooling and cleaning method. This involves shutting down the furnace, cooling it to room temperature, manually scraping away the solidified contaminated crucible bottom material, reloading, vacuuming, and heating up for crystal pulling. However, this method has the following drawbacks: Low production efficiency: From detecting minority carrier lifetime anomalies and stopping crystal pulling to cooling to room temperature, manually cleaning the crucible, and reheating for feeding, the entire process takes 10-13 hours, consuming a significant amount of production time; Wear and tear on thermal components: Some graphite thermal components and crucibles are worn out before reaching the expected number of cycles, increasing the unit cost of auxiliary materials; Reduced equipment utilization: Premature furnace shutdown disrupts the production schedule. Reloading, vacuuming, and melting the material takes several hours, during which time the equipment is in a non-productive state, directly reducing the overall efficiency of the equipment and the actual capacity of the factory. Summary of the Invention

[0005] This application provides a suction fixture for a single crystal furnace and its cleaning method. Through the synergistic cooperation of the nested structure of the outer and inner chambers and the differential pressure adsorption process, problems such as low production efficiency, high wear and tear on hot zone components, and high safety hazards caused by furnace shutdown and cooling are solved. The differential pressure regulating device, through precise control of the main chamber pressurization and the inner chamber negative pressure extraction, drives the efficient adsorption of contaminated silicon liquid into the fixture, ensuring minimal impurity residue. Through dual innovation in structure and process, efficient and non-destructive cleaning of the contaminated crucible bottom material is achieved without furnace shutdown, significantly shortening cleaning time and greatly improving the operating efficiency of the single crystal furnace.

[0006] The first aspect of this application provides a suction fixture for a single crystal furnace, comprising:

[0007] Outer liner;

[0008] The inner liner is nested inside the outer liner and has a tubular portion for absorbing materials, at least a portion of which extends to the outside of the outer liner.

[0009] Differential pressure regulating device, which is connected to the inner liner, is used to regulate the pressure difference between the inner liner and the main chamber of the single crystal furnace;

[0010] The pressure difference between the main chamber of the single crystal furnace and the inner liner is used to draw the bottom material of the crucible into the inner liner through the tubular part.

[0011] The first aspect of this application provides a single-crystal furnace suction fixture comprising an outer liner, an inner liner, and a differential pressure regulating device. The inner liner is nested inside the outer liner and has a tubular portion for suctioning material, at least a portion of which extends outside the outer liner. The differential pressure regulating device is connected to the inner liner and is used to regulate the pressure difference between the inner liner and the main chamber of the single-crystal furnace. Through the pressure difference between the main chamber and the inner liner, the crucible bottom material is sucked into the inner liner through the tubular portion. Thus, the single-crystal furnace suction fixture provided in this application, through the nested structure of the outer and inner liners and the synergistic effect of the differential pressure adsorption process, solves the problems of low production efficiency, high heat field component loss, and high safety hazards caused by furnace shutdown and cooling. The differential pressure regulating device, through precise control of the main chamber pressurization and the inner liner negative pressure extraction, drives the efficient adsorption of contaminated silicon liquid into the fixture, ensuring minimal impurity residue. Through dual innovation in structure and process, efficient and non-destructive cleaning of contaminated crucible bottom material is achieved without furnace shutdown, significantly shortening cleaning time and greatly improving the operating efficiency of the single-crystal furnace.

[0012] In one possible implementation, a stepped structure is provided on the inner bottom wall of the outer liner, and the lower edge of the inner liner rests on the stepped structure so that the stepped structure can support the inner liner.

[0013] In one possible implementation, the top of the inner liner is integrally formed with the tubular portion, the middle section of the tubular portion is provided with a necked section, and a flange is integrally formed above the necked section.

[0014] The diameter of the flange is larger than the diameter of the necked section.

[0015] In one possible implementation, a screw-in assembly is also included, which is connected to the outer liner and is used to drive the outer liner and the inner liner nested assembly to screw into or out of the single crystal furnace.

[0016] In one possible implementation, a connector is also included, one end of which is connected to the outer liner, and the other end of which is used to connect to the screw-in assembly.

[0017] In one possible implementation, the outer liner is made of a carbon-carbon composite material, and the carbon-carbon composite material has a heat resistance temperature ≥1600°C and can be reused at least 80 times.

[0018] In one possible implementation, the inner liner is made of high-purity quartz, and the purity of the high-purity quartz is ≥99.99%, and the heat resistance temperature is ≥1500℃.

[0019] In one possible implementation, a control unit is also included, which is electrically connected to the screwing assembly and the differential pressure regulating device, for controlling the screwing speed, differential pressure regulation, and tooling cooling.

[0020] In one possible implementation, a position sensor is also included, which is electrically connected to the control unit for real-time monitoring of the tooling position.

[0021] The second aspect of this application provides a cleaning method for a suction fixture used in a single crystal furnace, comprising:

[0022] After confirming that silicon contamination caused abnormal minority carrier lifetime, the crystal rod was moved to the auxiliary chamber of the single crystal furnace, and the main chamber of the single crystal furnace was kept in a low vacuum state.

[0023] The inner liner is nested inside the outer liner, and the suction tool is screwed into the main chamber of the single crystal furnace above the surface of the molten silicon liquid through the connector;

[0024] The material suction device is gradually lowered, and preheating is carried out in sections at the center of the water-cooled furnace body and the lower edge of the guide tube.

[0025] The suction device is lowered so that the tubular part is immersed below the surface of the molten silicon. By adjusting the furnace chamber pressure, the molten silicon is drawn into the inner liner under the action of pressure difference, thus completing the suction process.

[0026] The material suction device is lifted into the water-cooled jacket for segmented cooling, and then rotated out of the furnace after cooling.

[0027] It should be understood that the second aspect of this application corresponds to the technical solution of the first aspect of this application, and the beneficial effects achieved by each aspect and the corresponding feasible implementation are similar, and will not be repeated here.

[0028] In addition to the technical problems solved by this application, the technical features constituting the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions described above, other technical problems that can be solved by the single crystal furnace suction tool and its cleaning method provided by this application, other technical features contained in the technical solutions, and the beneficial effects brought about by these technical features will be further explained in detail in the specific embodiments. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are only a part of the embodiments of this application. These drawings and text descriptions are not intended to limit the scope of the concept of this application in any way, but to illustrate the concept of this application to those skilled in the art by referring to specific embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the structure of the suction tool for a single crystal furnace provided in an embodiment of this application;

[0031] Figure 2 This is a schematic diagram of the suction tool for a single crystal furnace provided in an embodiment of this application from another angle.

[0032] Figure 3 This is a cross-sectional schematic diagram of the suction fixture for a single crystal furnace provided in an embodiment of this application;

[0033] Figure 4 A schematic diagram of the structure of the suction tool for a single crystal furnace and its cooperation with the main chamber of the single crystal furnace provided in the embodiments of this application;

[0034] Figure 5 This is a schematic flowchart illustrating the cleaning method for the suction fixture used in a single crystal furnace provided in an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures:

[0036] 100 - Suction tooling for single crystal furnace;

[0037] 200 - Outer liner; 210 - Stepped structure;

[0038] 300 - Inner liner; 310 - Tubular section; 311 - Necked section; 312 - Flange;

[0039] 400-Single Crystal Furnace Main Chamber. Detailed Implementation

[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0041] As described in the background section, existing single-crystal furnace feeding fixtures typically employ a furnace-opening cooling and cleaning method to address impurities during crystal pulling. This involves shutting down the furnace, cooling to room temperature, manually scraping away the solidified contaminated crucible bottom material, reloading, vacuuming, and reheating for crystal pulling. However, this method has the following drawbacks: low production efficiency: from detecting minority carrier lifetime anomalies and stopping crystal pulling to cooling to room temperature, manually cleaning the crucible, and reheating for feeding, the entire process takes 10-13 hours, consuming significant production time; wear and tear on thermal components: some graphite thermal components and crucibles are worn out before reaching their expected lifespan, increasing the unit cost of auxiliary materials; reduced equipment utilization: premature furnace shutdown disrupts production scheduling. Reloading, vacuuming, and material processing take several hours, during which time the equipment is in a non-productive state, directly reducing overall equipment efficiency and the factory's actual capacity.

[0042] To address the aforementioned technical problems, the first aspect of this application provides a material suction fixture for a single crystal furnace. This fixture includes an outer liner, an inner liner, and a differential pressure regulating device. The inner liner is nested inside the outer liner and has a tubular portion for suctioning material, at least a portion of which extends outside the outer liner. The differential pressure regulating device is connected to the inner liner and is used to regulate the pressure difference between the inner liner and the main chamber of the single crystal furnace. Through the pressure difference between the main chamber and the inner liner, the bottom material is sucked into the inner liner through the tubular portion. Thus, the material suction fixture for a single crystal furnace provided in this application, through the nested structure of the outer and inner liners and the synergistic effect of the differential pressure adsorption process, solves the problems of low production efficiency, high heat field component losses, and high safety hazards caused by furnace shutdown and cooling. The differential pressure regulating device, through precise control of the main chamber pressurization and the inner liner negative pressure extraction, drives the efficient adsorption of contaminated silicon liquid into the fixture, ensuring minimal impurity residue. Through dual innovation in structure and process, efficient and non-destructive cleaning of contaminated crucible bottom material is achieved without furnace shutdown, significantly shortening cleaning time and greatly improving the operating efficiency of single crystal furnace.

[0043] The second aspect of this application provides a method for cleaning a suction fixture for a single crystal furnace. This method includes, after confirming that silicon contamination is causing abnormal minority carrier lifetime, raising the crystal rod to the auxiliary chamber of the single crystal furnace while maintaining a low vacuum in the main chamber; nesting the inner liner inside the outer liner and screwing the suction fixture into the main chamber above the molten silicon surface using a connector; gradually lowering the suction fixture, performing segmented preheating at the furnace water-cooling center and the lower edge of the guide tube; lowering the suction fixture until the tubular portion is immersed below the molten silicon surface, and adjusting the furnace chamber pressure to draw the molten silicon into the inner liner under pressure differential, thus completing the suction; raising the suction fixture into the water-cooling jacket for segmented cooling, and then screwing it out of the furnace.

[0044] To make the above-mentioned objectives, features, and advantages of the embodiments of this application more apparent and understandable, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0045] This application provides a suction fixture for a single crystal furnace and its cleaning method. Through the synergistic cooperation of the nested structure of the outer and inner chambers and the differential pressure adsorption process, problems such as low production efficiency, high heat field component wear, and high safety hazards caused by furnace shutdown and cooling are solved. The differential pressure regulating device, through precise control of the main chamber pressurization and the inner chamber negative pressure extraction, drives the efficient adsorption of contaminated silicon liquid into the fixture, ensuring minimal impurity residue. Through dual innovation in structure and process, efficient and non-destructive cleaning of the contaminated crucible bottom material is achieved without furnace shutdown, significantly shortening cleaning time and greatly improving the operating efficiency of the single crystal furnace. The specific structure of the suction fixture for a single crystal furnace and its cleaning method provided in this application will be described below with reference to the accompanying drawings.

[0046] refer to Figure 1 , Figure 2 as well as Figure 3 This application provides a material suction fixture 100 for a single crystal furnace in a first aspect. The single crystal furnace material suction fixture 100 may include an outer liner 200, an inner liner 300, and a differential pressure regulating device (not shown in the figure). In this embodiment, the outer liner 200 has an internal cavity, and the inner liner 300 can be entirely nested within the internal cavity of the outer liner 200. Furthermore, a tubular portion 310 may be provided inside the inner liner 300, and at least a portion of the tubular portion 310 may extend outside the outer liner 200 to directly contact the molten silicon. It is understood that the tubular portion 310 can be used to suction material. Figure 4 As shown, the differential pressure regulating device can be connected to the inner liner 300 and linked to the pressure control system of the main chamber 400 of the single crystal furnace, so that the differential pressure regulating device can be used to regulate the pressure difference between the inner liner 300 and the main chamber 400 of the single crystal furnace.

[0047] Exemplarily, in one possible implementation, the differential pressure regulating device may include components such as a throttle valve, a ball valve, and a quick-acting valve, for regulating the pressure difference between the inner liner 300 and the main chamber 400 of the single crystal furnace. Additionally, the tubular portion 310 may extend 20-30 mm beyond the outer liner 200, thereby facilitating the material intake by the tubular portion 310. The embodiments described in this application are not intended to be limiting.

[0048] Thus, the single-crystal furnace suction fixture 100 provided in this embodiment achieves synergistic optimization of high-temperature strength and chemical inertness through the nested structure of the outer liner 200 and the inner liner 300. The outer liner 200 bears the thermal radiation and mechanical load, while the inner liner 300 provides a clean silicon liquid channel. The differential pressure regulating device utilizes the precise combination of the positive pressure in the main chamber and the negative pressure in the inner liner 300 to form a stable and controllable adsorption driving force, enabling the contaminated silicon liquid to be rapidly drawn into the inner liner 300 through the tubular part 310. Compared with the furnace shutdown and cooling cleaning in related technologies, the single-crystal furnace suction fixture 100 provided in this embodiment can directly complete the suction while hot, avoiding production efficiency loss and accelerated aging of hot zone components due to repeated heating and cooling, while also eliminating the safety risks of manual slag removal.

[0049] Continue to refer to Figure 3 Based on the above embodiments, in one possible implementation, a step structure 210 may be provided on the inner bottom wall of the outer liner 200, and the lower edge of the inner liner 300 may be placed on the step structure 210, so that the step structure 210 can be used to support the inner liner 300.

[0050] In a specific embodiment, a raised step structure 210 is machined or assembled on the inner bottom wall of the outer liner 200, and the step surface can be perpendicular to the side wall of the outer liner 200. The lower edge of the inner liner 300 is designed as a matching flat surface or flange. During installation, the inner liner 300 is placed into the outer liner 200 from top to bottom, so that the lower edge of the inner liner 300 is precisely placed on the step structure 210. The bearing surface of the step structure 210 and the lower edge of the inner liner 300 do not require welding or bolt fixing, and are maintained in contact only by gravity.

[0051] In this embodiment, it is understood that the stepped structure 210 provides simple and reliable axial positioning and support for the inner liner 300, preventing it from sinking or shaking during use. Due to the non-fastening connection, stress concentration or jamming failures caused by differences in thermal expansion coefficients will not occur at high temperatures, and the inner liner 300 can be easily removed for replacement or cleaning. Simultaneously, the stepped structure 210 separates the bottom of the inner liner 300 from the bottom of the outer liner 200 by a certain gap, which is beneficial for the uniform distribution of heat conduction and reduces the impact of localized overheating on the tooling's lifespan.

[0052] Continue to refer to Figure 1 Based on the above embodiments, the top of the inner liner 300 can be integrally formed with the tubular portion 310. In one possible implementation, the middle section of the tubular portion 310 may have a necked section 311, and a flange 312 may be integrally formed above the necked section 311. In this embodiment, the diameter of the flange 312 can be larger than the diameter of the necked section 311.

[0053] In a specific embodiment, the top of the inner liner 300 and the tubular portion 310 are integrally formed using high-purity quartz or the same material, avoiding any seams or welding. The middle section of the tubular portion 310 has a significantly narrowed neck section 311. Above the neck section 311, an integrally formed flange 312 extends radially outwards. The outer diameter of the flange 312 is significantly larger than the outer diameter of the neck section 311, and the lower surface of the flange 312 forms a right angle or an inclined transition with the root of the neck section 311.

[0054] In the embodiments of this application, it is understood that the necked section 311 can significantly increase the flow rate of molten silicon in the tubular section 310 under the same pressure differential, enhancing the shearing and carrying capacity of residues at the bottom of the crucible, while reducing the amount of air pumped out per feeding cycle. The flange 312 structure serves two purposes: firstly, it limits and prevents the tooling from accidentally inserting too deeply into the molten silicon or coming out during the feeding process; secondly, it facilitates gripping and disassembly of the fixture after cooling. The one-piece molding avoids the risk of leakage or contamination at the joints of multiple components, ensuring the long-term high purity and structural integrity of the inner liner 300.

[0055] Based on the above embodiments, in one possible implementation, the single crystal furnace suction fixture 100 may further include a screw-in assembly (not shown in the figure). In this embodiment, the screw-in assembly is connected to the outer liner 200. It is understood that the screw-in assembly can be used to drive the nested assembly of the outer liner 200 and the inner liner 300 to screw into or out of the single crystal furnace.

[0056] In a specific embodiment, the rotary feed assembly may include a drive motor, a reducer, a lead screw, or a rotary feed mechanism. The output end of the rotary feed assembly can mate with the connection interface of the outer liner 200. The rotary feed assembly is installed in the auxiliary chamber of the single crystal furnace. A retractable drive rod drives the outer liner 200 and the nested inner liner 300 to achieve rotary feed motion, allowing the material suction fixture to safely rotate into a predetermined position inside the furnace from outside, and then rotate out in the opposite direction after material suction is completed.

[0057] For example, the screw-in assembly can smoothly screw into or out of the furnace at a constant speed of 800 mm / min. The screw-in speed of 800 mm / min is optimized to ensure the efficiency of the cleaning operation while preventing tooling wobbling or silicon molten material splashing due to excessive speed.

[0058] In the embodiments of this application, it is understood that the rotary feeding assembly achieves automated mechanical docking between the material suction fixture and the single crystal furnace, eliminating the need for manual hand-held operation near the high-temperature furnace opening, significantly reducing the risk of burns and mechanical injuries. Compared to direct insertion, the rotary feeding method offers better guiding accuracy and self-locking capability, preventing the fixture from accidentally falling off due to furnace vibration or pressure fluctuations.

[0059] Based on the above embodiments, in one possible implementation, the single crystal furnace suction fixture 100 may further include a connector (not shown in the figure), one end of which may be connected to the outer liner 200, and the other end of which may be used to connect to the screw-in assembly.

[0060] In a specific embodiment, one end of the connector is fixedly connected to the hole at the top of the outer liner 200 by bolts or pins, and the other end of the connector is connected to the end of the drive rod of the screw-in assembly by a quick-detachable plug-in structure. The length of the connector can be selected or customized according to the furnace depth of the single crystal furnace.

[0061] For example, the connector can be a high-strength tungsten wire rope. This high-strength tungsten wire rope uses multi-strand stranded tungsten wire rope with a diameter of 6–10 mm, has a high-temperature resistance of not less than 1800℃, and a tensile strength of not less than 500 MPa, and can safely bear the overall weight of the tooling (≤25 kg). Replacing metal rods or chains with high-strength tungsten wire rope fundamentally solves the problems of softening, creep, or breakage of mechanical transmission components under high-temperature environments. The tungsten wire rope maintains a tensile strength greater than 500 MPa even at 1800℃, and its multi-strand stranded structure has excellent flexibility, effectively absorbing minor vibrations during tooling movement and preventing rigid collisions that could damage hot components inside the furnace.

[0062] In the embodiments of this application, it is understood that the connector acts as a transition bridge between the tooling and the screw-in assembly, preventing the screw-in assembly from directly contacting the high-temperature area of ​​the outer liner 200, thus extending the service life of the drive mechanism. The quick-disassembly design allows the same screw-in assembly to be adapted to tooling of different specifications, improving the equipment's versatility. Furthermore, the connector can be quickly separated after the tooling cools, facilitating the removal of the inner liner 300 for waste disposal and shortening the cleaning cycle.

[0063] Based on the above embodiments, in one possible implementation, exemplarily, the outer liner 200 can be made of carbon fiber reinforced carbon-based composite material (carbon-carbon composite material), and the carbon-carbon composite material has a heat resistance temperature ≥1600℃ and can be reused at least 80 times. The embodiments in this application are not intended to be limiting.

[0064] In a specific embodiment, the outer liner 200 is integrally molded or machined from a carbon-carbon composite material. The material has a heat resistance temperature of not less than 1600℃, and can withstand the heat radiation and heat conduction of high-temperature molten silicon in the main chamber 400 of the single crystal furnace for a long time. Under normal use conditions, the outer liner 200 can be reused at least 80 times, and after each use, it can be reassembled simply by removing the surface deposits.

[0065] In the embodiments of this application, it is understood that carbon-carbon composite materials possess low density, high specific strength, excellent thermal shock resistance, and an extremely low coefficient of thermal expansion, maintaining dimensional stability and mechanical properties even at high temperatures. Compared to graphite or metal outer shells, carbon-carbon materials do not introduce metallic impurities that contaminate the furnace atmosphere at high temperatures. A lifespan of over 80 heats significantly reduces consumable costs and eliminates the need for frequent tooling changes, ensuring consistency in the material feeding process.

[0066] Based on the above embodiments, in one possible implementation, exemplarily, the inner liner 300 is made of high-purity quartz, and the purity of the high-purity quartz is ≥99.99%, and the heat resistance temperature is ≥1500℃.

[0067] In a specific embodiment, the inner liner 300 is made of high-purity quartz material with a purity of not less than 99.99%, and the total concentration of impurity elements (such as Fe, Ni, Cu, Al, etc.) is controlled below 10 ppm. The heat resistance temperature of the inner liner 300 is not less than 1500℃, and it will not soften or precipitate microparticles when in contact with molten silicon. The inner liner 300 has a uniform wall thickness, and the inner surface is polished to reduce silicon adhesion and crystallization residue.

[0068] In the embodiments of this application, it is understood that high-purity quartz has good chemical compatibility with molten silicon and will not introduce additional metal contamination during the feeding process, thereby ensuring the minority carrier lifetime of the remaining clean silicon material. The low thermal conductivity of quartz helps maintain the fluidity of the molten silicon in the tubular section 310 during feeding, preventing premature solidification and blockage. The polished inner surface makes it easy to remove the waste silicon block as a whole after feeding, reducing the difficulty of cleaning. Even after multiple thermal cycles, the transparency of the quartz inner liner 300 can still assist in visual inspection for cracks or contamination residues.

[0069] Based on the above embodiments, in one possible implementation, the single crystal furnace suction fixture 100 may further include a control unit (not shown in the figure). In this embodiment, the control unit is electrically connected to the spiral advance assembly and the differential pressure regulating device. It is understood that the control unit can be used to control the spiral advance speed, differential pressure regulation, and fixture cooling.

[0070] In the embodiments of this application, it is understood that the control unit transforms the material feeding operation, which originally relied on manual experience, into a standardized and automated process, significantly reducing the skill threshold and the probability of human error. By precisely controlling the spiral speed, the timing of differential pressure establishment, and the cooling rate, problems such as tooling breakage, silicon molten metal splashing, or incomplete material feeding can be effectively avoided. The linkage between the control unit and the furnace pressure system allows the material feeding process to be seamlessly connected with the normal crystal pulling process in the main chamber, enabling furnace-stop operation and greatly shortening the overall cleaning time.

[0071] Based on the above embodiments, in one possible implementation, the single crystal furnace suction fixture 100 may further include a position sensor (not shown in the figure). In this embodiment, the position sensor may be electrically connected to the control unit. It is understood that the position sensor can be used to monitor the position of the fixture in real time.

[0072] In this embodiment, it is understood that the position sensor enables closed-loop control of the tooling stroke, ensuring precise and controllable immersion depth of the tubular section 310 in the molten silicon, preventing damage to the tooling due to excessive depth or interruption of material feeding due to insufficient depth. During segmented preheating and cooling, the position information ensures that the tooling accurately remains within the set temperature range, optimizing thermal stress management. The position sensor data can also be used to record the position trajectory of each material feeding, providing quantitative basis for process optimization and quality traceability. Furthermore, when the position sensor detects an abnormal position deviation, the control unit immediately stops the rotation and issues an alarm to prevent the tooling from colliding with hot components.

[0073] refer to Figure 5 This application provides a second aspect of a cleaning method for a single-crystal furnace suction fixture 100. The cleaning method may include: after confirming that silicon contamination has caused abnormal minority carrier lifetime, raising the crystal rod to the auxiliary chamber of the single-crystal furnace and maintaining a low vacuum state in the main chamber 400; nesting the inner liner 300 within the outer liner 200, and screwing the suction fixture into the main chamber 400 above the molten silicon surface using a connector; gradually lowering the suction fixture, performing segmented preheating at the furnace water-cooling center and the lower edge of the guide tube; lowering the suction fixture so that the tubular portion 310 is immersed below the molten silicon surface, and by adjusting the furnace chamber pressure, drawing the molten silicon into the inner liner 300 under pressure differential, thus completing the suction; raising the suction fixture into the water-cooling jacket for segmented cooling, and then screwing it out of the furnace.

[0074] Figure 5 A schematic flowchart illustrating a cleaning method for a single crystal furnace suction fixture 100 provided in this application embodiment is shown below. Figure 5 As shown in the embodiment of this application, a cleaning method for a single crystal furnace suction fixture 100 includes:

[0075] S501. After confirming that silicon contamination has caused abnormal minority carrier lifetime, the crystal rod is lifted to the auxiliary chamber of the single crystal furnace, and the main chamber 400 of the single crystal furnace is kept in a low vacuum state.

[0076] During the single crystal pulling process, the crystal quality is monitored in real time by an online minority carrier lifetime detector. If an abnormal minority carrier lifetime is detected and confirmed to be caused by silicon material contamination, the control system does not immediately shut down the furnace, but continues pulling the crystal until the remaining material at the bottom of the crucible is controlled within the range of 2-15 kg. At this time, the pulled crystal rod is safely lifted to the auxiliary chamber, and the flap valve between the auxiliary chamber and the main chamber is closed to isolate the main and auxiliary chambers and prevent the contaminated atmosphere from spreading to the crystal rod. At the same time, the main chamber maintains a low vacuum of 8 torr to keep the molten silicon in a clean and stable thermal environment. Outside the furnace, the operator nests the high-purity quartz inner liner 300 inside the carbon-carbon composite outer liner 200, ensuring that the lower edge of the inner liner 300 is precisely placed on the stepped structure 210 on the bottom wall of the outer liner 200, ensuring that the quartz tube necking section 311 flange 312 is installed in place, and that the quartz tube extends 20-30 mm outward from the bottom through hole of the outer liner 200, completing the rapid assembly of the tooling.

[0077] In this embodiment, by controlling the crucible bottom material to 2-15 kg instead of pulling it all out, both the damage caused by dry burning of the crucible due to insufficient material and the reduction of the total amount of material to be sucked in later are avoided, thus shortening the cleaning time. Maintaining a low vacuum of 8 torr in the main chamber effectively inhibits the thickening of the oxide film on the surface of the contaminated silicon melt, reducing the suction resistance. The stepped nesting and pre-extension design of the tooling assembly ensures the repeatability of the assembly, fixing the extension length of the quartz tube and providing a reliable benchmark for the subsequent immersion depth in the silicon melt. The entire preparation process does not require furnace shutdown and cooling; the single crystal furnace thermal field remains at a high temperature, creating conditions for efficient subsequent material suction.

[0078] S502. The inner liner 300 is nested inside the outer liner 200, and the suction tool is screwed into the main chamber 400 of the single crystal furnace above the surface of the molten silicon liquid through the connector.

[0079] The operator inserts a high-purity quartz inner liner 300 into a carbon-carbon composite outer liner 200, ensuring the lower edge of the inner liner 300 sits precisely on the stepped structure 210 on the bottom wall of the outer liner 200, thus guaranteeing the stability of the tooling assembly. One end of the connector is then fixedly connected to the flange 312 interface of the outer liner 200, and the other end is connected to the drive rod of the screw-in assembly. The screw-in speed is set to 800 mm / min by the control unit, and the screw-in assembly is activated to screw the material suction tooling into the main chamber along the feeding hole or observation hole of the single crystal furnace, ultimately positioning it above the surface of the molten silicon. A position sensor provides real-time feedback on the tooling coordinates, and the control unit automatically stops screwing in when the predetermined position is reached.

[0080] In this embodiment, the stepped nested structure of the outer liner 200 and inner liner 300 achieves reliable positioning without additional fasteners, avoiding the risk of metal bolts jamming or contaminating the molten metal at high temperatures. The screw-in assembly, in conjunction with the connector, enables automated and smooth transport of the tooling from outside the furnace to inside, eliminating the need for manual approach to the high-temperature furnace opening and significantly reducing the risk of burns and mechanical injuries. Simultaneously, the segmented screw-in speed is adjustable to prevent damage to the furnace's hot zone components due to impact or vibration. Closed-loop control by the position sensor ensures precise alignment of the tubular section 310 with the molten silicon surface, providing millimeter-level positioning accuracy for subsequent material suction.

[0081] S503. The material suction device is gradually lowered, and preheating is carried out in sections at the center of the water-cooled furnace body and the lower edge of the guide tube.

[0082] The process of rotating the crystal is preheated in three steps: First, the fixture is lowered to the center of the water-cooled section (based on the lower edge of the fixture) and left for 2 minutes to allow the fixture to be preheated. Second, the fixture is lowered to the lower edge of the guide tube and left for 5-10 minutes to allow the internal temperature of the fixture to rise further and become more uniform. Third, the fixture is lowered to near the liquid surface. When the exposed tubular part 310 of the inner liner 300 contacts and is lifted off the liquid surface, the liquid surface is observed to tremble slightly. The position of the crystal is then confirmed and recorded. The fixture is then lifted 10-20 mm and left for 5-10 minutes. At the same time, the crystal lifting speed is changed from 800 mm / min to 200 mm / min and the crucible rotation speed is changed from 1 rpm to 0 rpm.

[0083] In this embodiment, the three-step preheating method involves sequentially stopping at three different temperature zones, allowing the thermal stress of the carbon-carbon outer liner 200 and the quartz inner liner 300 to be released gradually, completely avoiding the risk of cracking caused by direct immersion in high-temperature molten silicon. When the liquid surface vibrates, the crystal position is recorded and the fixture is lifted, which can accurately calibrate the relative height between the tubular part 310 and the liquid surface. Subsequently, the crystal lifting speed is reduced and the crucible rotation is stopped, eliminating the interference of melt disturbance on the material suction process and creating statically stable liquid surface conditions for subsequent differential pressure adsorption.

[0084] S504. The suction device is lowered so that the tubular part 310 is immersed below the surface of the molten silicon liquid. By adjusting the furnace chamber pressure, the molten silicon liquid is drawn into the inner liner 300 under the action of pressure difference, thus completing the suction.

[0085] After the fixture enters the molten silicon, ensure that the lower edge of the fixture is inside the crucible, and that the protruding tubular part 310 is immersed 15–25 mm below the liquid surface. The operator manually operates the differential pressure regulating device in the following sequence: first, return the dry pump throttle valve opening to zero from its normal operating value (original throttle valve opening was 25%), then close the ball valve, and finally quickly open the quick-flush valve. Following this sequence, the furnace pressure rapidly increases from 8 torr to 80–140 torr. During this process, continuously observe the crucible weight value and the remaining material in the crucible displayed on the sensor. When molten silicon begins to be drawn into the fixture, simultaneously lower the fixture manually by another 2–3 mm. Once the sensor weight value reaches its maximum value and no longer changes, the material intake is confirmed to be complete.

[0086] In this embodiment, it is understood that the immersion depth of the tubular part 310, 15–25 mm, ensures sufficient submersion of the suction port while avoiding excessive depth that would cause the bottom of the tooling to contact the bottom of the crucible. The strict sequence of zeroing the throttle valve, closing the ball valve, and opening the quick-flush valve first cuts off the dry pump's evacuation path to the main chamber, then opens the high-pressure gas source, causing the main chamber pressure to jump from low vacuum to positive pressure in a very short time. This creates a stable pressure difference of 80–130 torr between the main chamber pressure and the original low vacuum state of the inner liner 300, driving the molten contaminated silicon liquid to be drawn into the inner liner 300 at high speed. Manually lowering the tooling by 2–3 mm during the suction process compensates for the reduced immersion depth due to the drop in liquid level, maintaining a continuous and efficient suction driving force. A stable weight value indicates that the inner liner 300 is full and the residual silicon liquid at the bottom of the crucible has been completely removed. The entire process is fast, reliable, and requires no furnace shutdown.

[0087] S505. The material suction device is lifted into the water-cooled jacket for segmented cooling, and then rotated out of the furnace after cooling.

[0088] After material suction is completed, the control unit instructs the screw-in assembly to vertically lift the fixture to the water-cooling jacket area. The fixture's position within the water-cooling jacket is adjusted according to the suction volume (0–6 kg or 6–13 kg): for 0–6 kg, one-third of the fixture's length is positioned inside the water-cooling jacket, and two-thirds above it; for 6–13 kg, half of the fixture's length is positioned inside the water-cooling jacket, and half above it. A cooling timer is set for 5–10 minutes. After the timer expires, a 20-second wait is allowed before the fixture is lifted to a position where it can be isolated, i.e., between the main and auxiliary chamber flap valves. The flap valves are then closed to isolate the main and auxiliary chambers.

[0089] In the embodiments of this application, it is understood that cooling in different zones according to the amount of material sucked can avoid the problem of inconsistent cooling rates caused by differences in the amount of waste silicon in the tooling: when the amount of material sucked is small, the center of gravity of the tooling is higher, and one-third immersion in water cooling is sufficient for heat dissipation; when the amount of material sucked is large, the water cooling immersion ratio needs to be increased to accelerate the cooling of the core area. The forced cooling time of 5 to 10 minutes reduces the surface temperature of the tooling from about 1400°C to below 300°C, significantly shortening the several hours required for natural cooling. An additional 20-second wait ensures sufficient cooling, after which the tooling is raised to the isolation position and the flap valve is closed, so that subsequent furnace unloading operations will not disturb the main chamber thermal field, preparing for continuous feeding production.

[0090] Additionally, once the tooling is completely removed from the furnace, new silicon material is immediately added. When adding the first cylinder, before preparing to unload and open the quartz cone, a power increase operation is performed: the guide tube is raised to its upper limit, and the heating power is set to 90kW + 60kW (total 150kW). The first three cylinders of silicon material are processed using this power (90kW + 60kW); starting from the fourth cylinder, the power is changed to the mass production processing power (i.e., the processing power setting value during normal crystal pulling).

[0091] In this embodiment, it is understood that raising the guide tube to its upper limit increases the thermal radiation space within the furnace, preventing the guide tube from obstructing the direct heating of the upper part of the crucible by the heater. The first three tubes use a high-power melting system of 150 kW, which can quickly melt the cold silicon material, compensating for the heat loss caused by the short-term drop in the furnace's thermal field after material suction and cleaning, and shortening the material melting waiting time; at the same time, it avoids the impact on furnace pressure and oxygen content control caused by insufficient power leading to prolonged unmelted silicon material. Starting from the fourth tube, the production power is restored, indicating that the furnace's thermal field has returned to a steady state, and the normal crystal pulling process can then begin. This feeding strategy enables rapid resumption of production after material suction and cleaning, minimizing the impact of furnace shutdown, and shortening the overall production cycle by more than 80% compared to the traditional furnace shutdown cooling and cleaning method.

[0092] In this embodiment, the single-crystal furnace suction fixture 100 provided solves the problems of low production efficiency, high heat field component wear, and high safety hazards caused by furnace shutdown and cooling through the nested structure of the outer liner 200 and the inner liner 300 and the synergistic cooperation of differential pressure adsorption technology. The differential pressure regulating device drives the contaminated silicon liquid to be efficiently adsorbed into the fixture through precise control of the main chamber pressurization and the inner liner 300 negative pressure, ensuring that the impurity residue rate is minimized. Through dual innovation in structure and process, efficient and non-destructive cleaning of the contaminated crucible bottom material is achieved without furnace shutdown, significantly shortening the cleaning time and greatly improving the operating efficiency of the single-crystal furnace.

[0093] The various embodiments or implementation methods described in this specification are presented in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.

[0094] It should be noted that phrases such as "in specific implementations," "in some embodiments," "in this embodiment," and "exemplarily" in the specification indicate that the described embodiments may include specific features, structures, or characteristics, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not, is within the knowledge scope of those skilled in the art.

[0095] Generally speaking, terms should be understood at least in part by their use in context. For example, at least in part by context, the term "one or more" as used in the text can be used to describe any feature, structure, or characteristic of the singular meaning, or a combination of features, structures, or characteristics of the plural meaning. Similarly, at least in part by context, terms such as "a" or "the" can also be understood to convey either singular or plural usage.

[0096] It should be readily understood that “on,” “above,” and “on top of” in this disclosure should be interpreted in the broadest manner, such that “on” means not only “directly on something” but also “on something” with an intermediate feature or layer therebetween, and that “above” or “on top of” means not only “on something” but also “on something” without an intermediate feature or layer therebetween (i.e., directly on something).

[0097] Furthermore, for ease of explanation, spatially relative terms such as "below," "below," "under," "above," and "above" may be used to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation other than those shown in the figures. The device may have other orientations (rotated 90 degrees or in other orientations), and the spatially relative descriptive terms used herein may be interpreted accordingly.

[0098] Finally, it should be noted that other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and alterations may be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A material suction fixture for a single crystal furnace, characterized in that, include: Outer liner (200); The inner liner (300) is nested inside the outer liner (200), and the inner liner (300) has a tubular portion (310) for absorbing materials, at least a portion of which extends outside the outer liner (200). A differential pressure regulating device is connected to the inner liner (300) and is used to regulate the pressure difference between the inner liner (300) and the main chamber (400) of the single crystal furnace; The crucible bottom material is drawn into the inner liner (300) through the tubular part (310) by the pressure difference between the main chamber (400) of the single crystal furnace and the inner liner (300).

2. The feeding fixture for a single crystal furnace according to claim 1, characterized in that, The inner bottom wall of the outer liner (200) is provided with a stepped structure (210), and the lower edge of the inner liner (300) rests on the stepped structure (210) so that the stepped structure (210) can support the inner liner (300).

3. The feeding fixture for a single crystal furnace according to claim 2, characterized in that, The top of the inner liner (300) is integrally formed with the tubular part (310), the middle section of the tubular part (310) is provided with a necked section (311), and a flange (312) is integrally formed above the necked section (311). The diameter of the flange (312) is larger than the diameter of the necked section (311).

4. The feeding fixture for a single crystal furnace according to any one of claims 1-3, characterized in that, It also includes a screw-in assembly, which is connected to the outer liner (200) and is used to drive the outer liner (200) and the inner liner (300) nested assembly to screw into or out of the single crystal furnace.

5. The feeding fixture for a single crystal furnace according to claim 4, characterized in that, It also includes a connector, one end of which is connected to the outer shell (200), and the other end of which is used to connect to the screw-in assembly.

6. The feeding fixture for a single crystal furnace according to any one of claims 1-3, characterized in that, The outer liner (200) is made of carbon-carbon composite material, and the heat resistance temperature of the carbon-carbon composite material is ≥1600℃, and it can be reused at least 80 times.

7. The feeding fixture for a single crystal furnace according to any one of claims 1-3, characterized in that, The inner liner (300) is made of high-purity quartz, and the purity of the high-purity quartz is ≥99.99%, and the heat resistance temperature is ≥1500℃.

8. The suction fixture for a single crystal furnace according to claim 4, characterized in that, It also includes a control unit, which is electrically connected to the gyratory assembly and the differential pressure regulating device, and is used to control the gyratory speed, differential pressure regulation and tooling cooling.

9. The material suction fixture for a single crystal furnace according to claim 8, characterized in that, It also includes a position sensor, which is electrically connected to the control unit and is used to monitor the position of the suction tool in real time.

10. A cleaning method for a suction fixture used in a single crystal furnace, characterized in that, include: After confirming that silicon contamination caused abnormal minority carrier lifetime, the crystal rod was lifted to the auxiliary chamber of the single crystal furnace, and the main chamber (400) of the single crystal furnace was kept in a low vacuum state. The inner liner (300) is nested inside the outer liner (200), and the suction tool is screwed into the main chamber (400) of the single crystal furnace above the surface of the molten silicon liquid through the connector; The material suction device is gradually lowered, and preheating is carried out in sections at the center of the water-cooled furnace body and the lower edge of the guide tube. The suction device is lowered so that the tubular part (310) is immersed below the surface of the molten silicon liquid. By adjusting the furnace chamber pressure, the molten silicon liquid is drawn into the inner liner (300) under the action of pressure difference, thus completing the suction. The material suction device is lifted into the water-cooled jacket for segmented cooling, and then rotated out of the furnace after cooling.

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