Broken edge remelting process in later stage of crystal growth

Abstract

The invention provides a broken edge remelting process in the later stage of crystal growth. The broken edge remelting process comprises the following steps: S100, lowering the position of a crucible to separate the bottom end of a crystal from a liquid level; s200, the position of the crucible is adjusted, and the liquid opening distance is H; s300, the lower portion of the crystal extends into the crucible, and the distance between the bottom end of the crystal and the liquid level is L; s400, the rising height h of the liquid level in the crucible after the crystal located below the liquid level is molten back is determined; s500, the difference value between h1 and h2 is H, and H and h are compared; s600, if H is equal to h, the crystal below the crucible is molten back; if Hlt; h, the crystal below the crucible has not completed the remelting operation; s700, the H is made to be located at the position in the step S200 again; and S800, repeating the steps S300 to S600 until all the crystals are molten back. The invention provides a broken edge remelting process in the later stage of crystal growth, and aims to solve the problems that production equipment is easy to damage and even safety accidents are caused when crystals are remelted due to broken edges in the later stage of equal diameter or when the crystals are ended.

Description

Technical Field

[0001] The invention belongs to the technical field of crystal remelting, and more specifically, relates to a process for remelting broken edges in the late stage of crystal growth. Background Art

[0002] At present, the Czochralski method of crystal pulling is to place the raw materials in the crucible of the crystal pulling furnace, heat and melt the raw materials in the crystal pulling furnace, and then immerse a single crystal seed crystal in the melt. Through accurate temperature control, the melt is allowed to grow along the seed crystal, and through the process of seeding, shoulder release, shoulder rotation, equal diameter, and process, a crystal (also called crystal) for solar photovoltaic is finally formed. However, during the crystal growth process, crystal breakage (also called broken edge) often occurs.

[0003] According to the different growth stages of the crystal, the broken edges are divided into shoulder broken edges, early equal-diameter broken edges, late equal-diameter broken edges and tail broken edges. If the broken edges occur during shoulder or early equal-diameter period, since the melt in the crucible has not been reduced too much, the production staff can directly adjust the crucible to the seeding crucible position or the lower limit of the crucible and then melt the crystal back. The operation is simple and the risk is relatively low. If the broken edges occur in the late equal-diameter period or at the end, since the melt in the crucible is consumed more and the liquid level is low, the crucible cannot be directly lowered to a low position for remelting, otherwise it will affect the life of the crucible. Therefore, the production staff can only rely on constantly adjusting the position of the crucible during the remelting process to ensure the smooth remelting of the crystal, which not only threatens the personal safety of the production staff, but also may cause damage to the production equipment, raw materials, etc., resulting in a huge waste of manpower and material costs. Summary of the invention

[0004] The purpose of the present invention is to provide a process for melting back broken edges in the late stage of crystal growth, aiming to solve the problem that broken edges of crystals occur in the late stage of equal diameter or at the end, which easily causes damage to production equipment during crystal melting back and even causes safety accidents.

[0005] To achieve the above object, the technical solution adopted by the present invention is: A process for melting back broken edges in the late stage of crystal growth is provided, comprising: S100, lowering the crucible to separate the bottom of the crystal from the liquid surface, adjusting the power of the heater to the material melting power, so that the temperature of the melt in the crucible increases; S200, adjusting the position of the crucible so that the liquid mouth distance is H, 35 mm≤H≤50 mm, where the liquid mouth distance refers to the distance between the bottom end of the flow tube and the liquid surface; S300, extending the lower part of the crystal into the crucible and positioned below the melt, the distance between the bottom of the crystal and the liquid surface is L, 50 mm≤L≤200 mm, and starting to remelt the crystal; S400, obtaining a rising height h of the liquid level in the crucible after the crystal below the liquid level is melted back; S500. The liquid level distance h is the distance from the liquid level in the crucible to the crystal before the crystal located below the liquid level in the crucible starts to remelt. 1 , the liquid level distance h after the crystal located below the liquid level in the crucible remelts 2 , h 1 and h 2 The difference is △H, that is, the change value of the liquid level distance is △H, and compare the magnitudes of △H and h; S600. If △H = h, it means that the crystal below the crucible has finished remelting; if △H < h, it means that the crystal below the crucible has not completed the remelting operation; S700. If the crystal below the liquid level of the crucible has finished remelting, it means that this remelting is completed, and adjust the position of the crucible so that H returns to the position in step S200 again; S800. Repeat S300 - S600 until all the crystals have completed remelting.

[0006] In a possible implementation, S100 further includes adjusting the rotation speed of the crystal to 1 - 2 r / min and adjusting the rotation speed of the crucible to 0.5 - 1 r / min.

[0007] In a possible implementation, in S100, after adjusting the power of the heater, maintain the heating time for 15 - 30 min to increase the temperature of the melt in the crucible.

[0008] In a possible implementation, S400 specifically includes: S410. According to the height L of the crystal located below the liquid level in the crucible, the mass of the crystal can be calculated as: M = ρ 1 ×V 1 (1) where ρ 1 is the density of the crystal, and V 1 is the volume of the crystal; V 1 = πr 2 ×L (2) where r is the radius of the crystal, substitute formula (2) into formula (1) to obtain the mass of the crystal; S420. According to the law of conservation of mass, the mass of the crystal does not change before and after melting. Therefore, the volume V 2 after the crystal melts is: V 2 = M÷ρ 2 where ρ 2 is the density of the single crystal silicon after melting; M is obtained from S410; S430, according to the inner diameter of the crucible, the height h of the liquid level after the crystal is melted back can be calculated as: h = V 2 ÷(πR 2 ) Where R is the inner diameter of the crucible, V 2 Obtained from the S420.

[0009] In a possible implementation, in S410 , a caliper or a laser diameter gauge is used to measure the diameter of the crystal.

[0010] In a possible implementation, the S400 specifically includes: S410, calculate the mass of the crystal as: M=ρ 1 ×V 1 (1) Among them, ρ 1 is the density of the crystal, V 1 is the volume of the crystal; V 1 =πR 2 ×△L(2) Wherein, R is the inner diameter of the crucible, ΔL is the height difference of the liquid surface before and after the crystal enters the melt in the crucible. According to Archimedes' principle, the volume of the crystal below the liquid surface is consistent with the volume of the liquid discharged after the crystal enters the liquid surface; S420. According to the law of conservation of mass, the mass of the crystal does not change before and after melting, so the volume of the crystal after melting is V 2 for: V 2 = M÷ρ 2 Among them, ρ 2 is the density of single crystal silicon after melting; M is obtained from S410; S430, according to the inner diameter of the crucible, the height h of the liquid level after the crystal is melted back can be calculated as: h = V 2 ÷(πR 2 ) Where R is the inner diameter of the crucible, V 2 Obtained from the S420.

[0011] In a possible implementation, in S800, when the weight of the solid crystal is detected to be zero, it indicates that the crystal has been completely melted back.

[0012] In a possible implementation, in S800, a quality detector is provided in the furnace, and the quality detector is communicatively connected with an alarm. The quality detector is used to detect the quality of the solid-state crystal. When the quality detector detects that the quality of the solid-state crystal is zero, the alarm emits a sound wave and / or light wave alarm.

[0013] In a possible implementation, a distance detector is used in S200 to monitor the liquid mouth distance in real time, and in S300, the distance detector is used to detect that the distance L between the bottom end of the crystal and the liquid surface.

[0014] In a possible implementation, in S100 and S200, a lifting device is provided at the bottom of the crucible, and the lifting device is used to adjust the height of the crucible.

[0015] The beneficial effect of the broken edge remelting process in the late stage of crystal growth provided by the present invention is that: compared with the prior art, by accurately controlling the crucible position, the heater power and the distance between the crystal and the liquid surface, the high efficiency and controllability of the crystal remelting process are achieved. After the crystal is separated from the liquid surface, the temperature of the melt is increased by lowering the crucible position and adjusting the heater power, thereby providing the necessary thermodynamic conditions for the crystal remelting. During the remelting process, the liquid mouth distance (H) and the distance (L) between the bottom of the crystal and the liquid surface are adjusted to ensure that the crystal can be evenly heated during the remelting process and avoid the occurrence of local overheating or supercooling. In addition, by calculating the liquid level rise height (h) and the liquid mouth distance change value (△H), the remelting progress can be monitored in real time to ensure accurate control of the remelting process. As the remelting process progresses, the crucible position is repeatedly adjusted and the remelting steps are repeated to ensure that the crystal can be completely remelted and avoid the existence of residual unmelted parts. The present invention not only improves the efficiency and quality of crystal remelting, but also enhances the operability and stability of the process. During the remelting process, the change of the liquid mouth distance is controlled so that the liquid mouth distance is always maintained within a reasonable range for remelting, thereby avoiding deformation and damage of the crucible caused by being in a baking and heating state for a long time, and avoiding the problem of stress damage to the crucible caused by excessive crystal falling stroke, thereby improving the safety of remelting. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A flow chart of a process for melting back broken edges in a later stage of crystal growth provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] In the claims, specification and the above drawings of the present invention, unless otherwise clearly defined, the terms "first", "second" or "third" are used to distinguish different objects, rather than to describe a specific order. Unless otherwise specified, other directional words, such as "vertical", "clockwise", "counterclockwise", etc., indicating directions or positional relationships are based on the directions and positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, so it cannot be understood as limiting the specific protection scope of the present invention. In the claims, specification and the above drawings of the present invention, unless otherwise clearly defined, the terms "fixed connection" or "fixed connection" should be understood in a broad sense, that is, any connection method without a displacement relationship and relative rotation relationship between the two, that is, including non-detachable fixed connection, detachable fixed connection, integrated connection and fixed connection through other devices or elements. In the claims, specification and the above drawings of the present invention, the terms "including", "having" and their variations are used, and the intention is to "include but not limited to".

[0020] See also Figure 1 The present invention provides a method for melting back the broken edges of a crystal at a later stage of crystal growth. The method comprises: S100, lowering the crucible to separate the bottom of the crystal from the liquid surface, adjusting the power of the heater to the material melting power, and raising the temperature of the melt in the crucible; S200, adjust the position of the crucible so that the liquid mouth distance is H, 35 mm≤H≤50 mm, the liquid mouth distance refers to the distance between the bottom end of the flow tube and the liquid surface; S300, insert the lower part of the crystal into the crucible and place it below the melt, the distance between the bottom of the crystal and the liquid surface is L, 50 mm≤L≤200 mm, and start to remelt the crystal; S400, obtaining a rising height h of the liquid level in the crucible after the crystal below the liquid level is melted back; S500, the distance from the liquid mouth before the crystal below the liquid surface in the crucible starts to melt back is h 1 , the distance h between the crystal below the liquid surface in the crucible and the liquid outlet after melting back 2 ,h 1 With h 2The difference is △H, that is, the change value of the liquid outlet distance is △H, and compare the magnitudes of △H and h; S600. If △H = h, it means that the crystal below the crucible has finished remelting; if △H < h, it means that the crystal below the crucible has not completed the remelting operation; S700. If the crystal below the crucible liquid level has finished remelting, it means that the current remelting is completed, adjust the position of the crucible to make H return to the position in step S200 again; S800. Repeat S300 - S600 until all the crystals have completed remelting.

[0021] Compared with the prior art, the crystal late-stage edge-breaking remelting process provided by the present invention realizes the high efficiency and controllability of the crystal remelting process by precisely controlling the position of the crucible, the power of the heater, and the distance between the crystal and the liquid level. After the crystal is separated from the liquid level, by lowering the position of the crucible and adjusting the power of the heater, the temperature of the molten liquid is increased, providing the necessary thermodynamic conditions for crystal remelting. During the remelting process, the liquid outlet distance (H) and the distance (L) between the bottom end of the crystal and the liquid level are adjusted to ensure that the crystal can be uniformly heated during remelting, avoiding local overheating or overcooling. In addition, by calculating the rising height (h) of the liquid level and the change value (△H) of the liquid outlet distance, the remelting progress can be monitored in real time to ensure precise control of the remelting process. As the remelting progresses, the position of the crucible is repeatedly adjusted and the remelting steps are repeated to ensure that the crystal can be completely remelted, avoiding the existence of residual unmelted parts. The present invention not only improves the efficiency and quality of crystal remelting, but also enhances the operability and stability of the process. During the remelting process, the change of the liquid outlet distance is controlled to keep the liquid outlet distance within a reasonable range for remelting, avoiding the deformation and damage of the crucible caused by the long-term baking and heating state of the crucible, and also avoiding the problem of the crucible being damaged due to the excessive falling stroke of the crystal, improving the safety of remelting.

[0022] Precise temperature control: In step S100, after lowering the position of the crucible to separate the bottom end of the crystal from the liquid level, adjust the power of the heater to the material melting power to increase the temperature of the molten liquid. This operation can ensure that before remelting, the molten liquid is in a suitable high-temperature state, providing good thermodynamic conditions for subsequent crystal remelting, helping the crystal to remelt uniformly, reducing remelting defects caused by uneven temperature, and ensuring the remelting quality.

[0023] Improve the safety of remelting: In step S200, the liquid outlet distance H is limited to 35mm - 50mm. A stable liquid outlet distance can avoid the safety accident caused by the molten liquid in the crucible engulfing the draft tube.

[0024] Optimizing the remelting process: In step S300, the bottom end of the crystal is inserted into the melt by a specific distance L (50 mm - 200 mm) below the melt surface to start remelting. Such a setting enables the crystal to be heated sufficiently and uniformly in the melt, ensuring that the remelting rate of each part of the crystal is similar, effectively avoiding excessive or insufficient local remelting, and being conducive to improving the integrity and quality uniformity of the crystal after remelting.

[0025] Real-time monitoring of the remelting progress: After the crystal remelting is completed in S400, the rising height h of the liquid level in the crucible is calculated, and in S500, the magnitudes of △H and h are compared to determine whether the remelting is completed. This method of real-time monitoring of the remelting progress based on the change of physical quantities can accurately grasp the remelting situation, avoid over-remelting or insufficient remelting, improve the control accuracy of the remelting process, and save time and raw material costs.

[0026] Ensuring the integrity of remelting: When it is determined in S600 that △H < h, the position of the crucible is adjusted in S700 to make H return to the specified value, and then S300 - S600 are repeated until the entire crystal is remelted. This cyclic operation ensures that the crystal can be completely remelted regardless of its size and shape, ensuring the integrity of the remelting operation and improving the qualified rate of the product.

[0027] It should be noted that after the existing crystal has a broken edge during the later stage of equal diameter or at the end, there are two remelting solutions: The first one is during the remelting process, first separate the crystal from the liquid surface. After the temperature of the melt in the crucible rises, synchronously lower the positions of the crucible and the crystal to perform the remelting operation, and then complete the crystal remelting by repeatedly executing this step.

[0028] The second one is during the remelting process, directly lower the crucible to the seeding crucible position or the lower limit position of the crucible to ensure that the melt liquid level is always in a safe position, and then complete the crystal remelting by continuously lowering the position of the crystal.

[0029] For the first remelting technology, the crucible and the crystal are lowered simultaneously. Since the amount of melt in the crucible is small and the liquid level is low in the later stage of equal diameter, the crystal is continuously converted into melt during the remelting process, which will cause the liquid level to rise. Therefore, it is necessary to match the descent range of the crucible and the crystal at all times. In the early stage of remelting, if the crystal drops too much, it may directly pierce the bottom of the crucible and cause a leakage accident; in the middle and late stages of remelting, the liquid level rises. If the crucible is not lowered in time during the remelting process, the melt may engulf the guide tube and cause a safety accident. Therefore, the descent range of the crucible and the descent range of the crystal need to be matched to a certain extent to avoid accidents as much as possible. As for the descent range of the crucible and the crystal, in most cases it is judged based on the experience of on-site production personnel, and the liquid level position needs to be observed visually in real time. There are no strict specifications, which greatly wastes manpower and time costs and cannot avoid the occurrence of safety accidents.

[0030] For the second remelting technology, the crucible is directly lowered to the seeding position or the lower limit for remelting. This method can ensure that the liquid level is always in a safe position during the remelting process and will not contact the guide tube. It is suitable for remelting operations of broken edges at the shoulder or the early stage of equal diameter. However, for remelting when the liquid level is at a low position in the later stage of equal diameter, the crucible will be in a baking and heating state for a long time without liquid, which may cause the crucible to deform in severe cases. In particular, after the crucible is directly lowered to the lower limit, the crucible is closer to the heater, which increases the speed of crucible deformation. Once the crucible is deformed, it means that the single crystal cannot be pulled any further, which greatly wastes costs.

[0031] In some embodiments, see Figure 1 , S100 also includes adjusting the rotation speed of the crystal to 1-2 r / min, and adjusting the rotation speed of the crucible to 0.5-1 r / min.

[0032] Adjusting the rotation speed of the crystal and crucible to a lower range (1-2 r / min and 0.5-1 r / min) not only optimizes the thermodynamic and kinetic conditions during the crystal remelting process, but also improves the stability, controllability and energy utilization efficiency of the process, providing a reliable guarantee for the growth and subsequent processing of high-quality crystals. This embodiment further optimizes the control accuracy and effect of the broken edge remelting process in the later stage of crystal growth. The slow rotation of the crystal and crucible can make the temperature distribution in the solution or melt more uniform, avoiding the occurrence of local overheating or supercooling. In addition, a lower rotation speed can effectively reduce turbulence and disturbance in the solution or melt, and avoid crystal surface damage or impurity introduction due to violent flow.

[0033] It should be noted that the melting point of single crystal silicon (crystal) is 1414°C, and the vaporization temperature is 2355°C. The temperature of the melt during the remelting process is near the melting point, and generally does not exceed 1450°C. This is because the crucible may deform under long-term baking at high temperature. After the crucible is deformed, the single crystal cannot be pulled, which will lead to waste of all raw materials (polysilicon, quartz crucible) and increase costs. Therefore, the temperature of the melt is strictly controlled during the remelting process, and the single crystal silicon will not be vaporized. It is only a transition between solid and liquid states, and there will be no quality change, and it will not affect the liquid level.

[0034] In some embodiments, see Figure 1 In S100, after adjusting the power of the heater, the heating time is maintained for 15-30 minutes to increase the temperature of the melt in the crucible.

[0035] Prolonging the heating time can ensure that the melt in the crucible fully absorbs heat and the overall temperature rises evenly. A heating time of 15-30 minutes can avoid uneven crystal remelting due to the temperature of some areas not meeting the remelting requirements due to too short heating time. It can ensure that the solution temperature rises effectively, create a good thermal environment for crystal remelting, and avoid energy waste and excessive equipment damage due to overheating. At the same time, a stable and suitable high-temperature environment will help the crystal to remelt at a similar rate in all parts during the subsequent remelting process, reduce remelting defects caused by temperature fluctuations, improve the quality and integrity of the crystal after remelting, and thus improve the product yield.

[0036] In some embodiments, see Figure 1 , S400 specifically includes: S410. According to the height L of the crystal below the liquid surface in the crucible, the mass of the crystal can be calculated as: M=ρ 1 ×V 1 (1) Among them, ρ 1 is the density of the crystal, V 1 is the volume of the crystal; V 1 =πr 2 × L (2) Where r is the radius of the crystal. Substituting formula (2) into formula (1) yields the mass of the crystal.

[0037] S420. According to the law of conservation of mass, the mass of the crystal does not change before and after melting, so the volume of the crystal after melting is V 2 for: V 2 = M÷ρ 2 Among them, ρ 2is the density of single crystal silicon after melting; M is obtained from S410; S430. According to the inner diameter of the crucible, the height h of the liquid level after the crystal is melted back can be calculated as: h = V 2 ÷(πR 2 ) Where R is the inner diameter of the crucible, V 2 Obtained from S420.

[0038] This embodiment provides an effective method for calculating relevant quantities of the crystal before and after melting based on the position of the crystal in the crucible and related physical parameters, which has many beneficial effects. In terms of crystal mass calculation, by measuring the height L of the crystal below the liquid surface in the crucible, combined with the crystal density ρ 1 The crystal mass M is calculated accurately using the formula based on the radius r, which provides basic data for subsequent calculations and provides a clear starting point for the study of crystal-related quantities. The volume V of the crystal after melting is calculated based on the law of conservation of mass. 2 This idea is clever and reasonable. It can effectively use the crystal mass data before melting to coherently deduce the volume after melting, which is of great significance for understanding the volume change law during the crystal state change process. Finally, according to the crucible inner diameter R and the volume after melting V 2 Calculate the height h of the liquid level rise. This calculation result is critical for monitoring and controlling the crystal melting process and ensuring that the production or experiment proceeds as expected in actual production or experiments. It helps to accurately control the process and improve product quality or experimental accuracy.

[0039] Specifically, ρ 1 2.33 g / cm 3 , ρ 2 2.53g / cm 3 .

[0040] In some embodiments, see Figure 1 In S410, a caliper or a laser diameter gauge is used to measure the diameter of the crystal.

[0041] In this embodiment, a simple measuring tool is used to obtain the diameter of the crystal, and then the radius of the crystal.

[0042] In some embodiments, see Figure 1 , S400 specifically includes: S410, calculate the mass of the crystal as: M=ρ 1 ×V 1 (1) Among them, ρ 1 is the density of the crystal, V 1 is the volume of the crystal; V 1 =πR 2 ×△L(2) Where R is the inner diameter of the crucible, △L is the height difference of the liquid surface before and after the crystal enters the melt in the crucible. According to Archimedes' principle, the volume of the crystal below the liquid surface is consistent with the volume of the liquid discharged after the crystal enters the liquid surface. S420. According to the law of conservation of mass, the mass of the crystal does not change before and after melting, so the volume of the crystal after melting is V 2 for: V 2 = M÷ρ 2 Among them, ρ 2 is the density of single crystal silicon after melting; M is obtained from S410; S430. According to the inner diameter of the crucible, the height h of the liquid level after the crystal is melted back can be calculated as: h = V 2 ÷(πR 2 ) Where R is the inner diameter of the crucible, V 2 Obtained from S420.

[0043] This embodiment uses the change in the liquid level in the crucible before and after the crystal is inserted to obtain the change in the volume of the solution, thereby obtaining the volume of the crystal in the melt according to Archimedes' principle, and thus the mass of the crystal in the melt can be calculated. This solution does not require measuring the diameter of the crystal, simplifying the measurement steps.

[0044] Specifically, ρ 1 2.33 g / cm 3 , ρ 2 2.53g / cm 3 .

[0045] In some embodiments, see Figure 1 In S800, when the weight of the solid crystal is detected to be zero, it indicates that the crystal has been completely melted back. By detecting the quality of the remaining crystal, the progress of the crystal remelting can be obtained, and then it can be determined whether the crystal is completely remelted.

[0046] In some embodiments, see Figure 1 In S800, a quality detector is arranged in the furnace, and the quality detector is connected to the alarm for communication. The quality detector is used to detect the quality of the solid crystal. When the quality detector detects that the quality of the solid crystal is zero, the alarm sends out a sound wave and / or a light wave alarm.

[0047] In step S800, by setting up a quality detector in the furnace and establishing a communication connection with the alarm, real-time monitoring of the quality of the solid crystal is achieved. The quality detector can accurately detect the quality changes of the solid crystal. When it is detected that the quality of the solid crystal drops to zero, it indicates that the crystal may have been completely melted or other abnormal conditions have occurred. At this time, the alarm will immediately trigger the sound wave and / or light wave alarm to promptly remind the operator to take corresponding measures. This design not only improves the automation level of the production process, but also significantly enhances safety and reliability, avoiding equipment damage or production accidents caused by complete melting of the crystal or other abnormal conditions. At the same time, real-time monitoring and alarm functions also help to optimize process parameters, improve production efficiency and product quality. Overall, step S800 provides important safety guarantees and quality control measures for the crystal melting process by introducing quality detectors and alarm systems.

[0048] In some embodiments, see Figure 1 In S200, a distance detector is used to monitor the liquid port distance in real time. In S300, a distance detector is used to detect that the distance L between the bottom of the crystal and the liquid surface is. In S200, the real-time monitoring of the liquid mouth distance by the distance detector ensures the stability of the liquid level height, provides uniform environmental conditions for crystal growth, and avoids crystal defects or uneven growth problems caused by liquid level fluctuations. In S300, by detecting the distance L between the bottom of the crystal and the liquid surface, the position and state of crystal growth can be accurately grasped, providing accurate data support for the subsequent calculation of crystal quality, volume and liquid level changes. This real-time monitoring mechanism not only improves the controllability and stability of the crystal growth process, but also significantly reduces human operation errors, improves production efficiency and product quality. In addition, through real-time data feedback, operators can adjust process parameters in time and optimize crystal growth conditions, thereby further improving the yield and performance of single crystal silicon. This embodiment does not need to rely on manual observation and experience, and improves the accuracy and safety of remelting.

[0049] In some embodiments, see Figure 1 In S100 and S200, a lifting device is provided at the bottom of the crucible, and the lifting device is used to adjust the height of the crucible. The position of the crucible is automatically adjusted by the lifting device without manual operation, which improves the adjustment effect and adjustment accuracy.

[0050] Optionally, the lifting device can be a hydraulic or pneumatic lifting rod, or a lead screw.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for melting back broken edges in the late stage of crystal growth, characterized in that: Including: S100. Lower the position of the crucible to separate the bottom end of the crystal from the liquid surface, and adjust the power of the heater to the material melting power to increase the temperature of the molten liquid in the crucible. S200. Adjust the position of the crucible so that the liquid port distance is H, where 35 mm ≤ H ≤ 50 mm. The liquid port distance refers to the distance between the bottom end of the deflector and the liquid surface. S300. Insert the lower part of the crystal into the crucible and place it below the molten liquid. The distance between the bottom end of the crystal and the liquid surface is L, where 50 mm ≤ L ≤ 200 mm, and start remelting the crystal. S400. Obtain the rising height h of the liquid surface in the crucible after the crystal remelting under the liquid surface is completed. S500. The liquid port distance before the crystal under the liquid surface in the crucible starts to remelt is h1, and the liquid port distance after the crystal under the liquid surface in the crucible is remelted is h2. The difference between h1 and h2 is ΔH, that is, the liquid port distance change value is ΔH. Compare the size of ΔH and h. S600. If ΔH = h, it means that the crystal below the crucible has been remelted; if ΔH < h, it means that the crystal below the crucible has not completed the remelting operation. S700. If the crystal below the liquid surface of the crucible has been remelted, it means that this remelting is completed. Adjust the position of the crucible so that H returns to the position in step S200 again. S800. Repeat S300 - S600 until all the crystals are remelted.

2. The crystal growth late stage broken edge melting back process as claimed in claim 1, characterized in that: The S100 further includes adjusting the rotation speed of the crystal to 1 - 2 r / min and adjusting the rotation speed of the crucible to 0.5 - 1 r / min.

3. The crystal growth late stage broken edge melting back process as claimed in claim 1, characterized in that: In the S100, after adjusting the power of the heater, maintain the heating time for 15 - 30 min to increase the temperature of the molten liquid in the crucible.

4. The crystal growth late stage broken edge melting back process as claimed in claim 1, characterized in that: The S400 specifically includes: S410. According to the height L of the crystal below the liquid surface in the crucible, the mass of the crystal can be calculated as: M = ρ1×V1 (1) where ρ1 is the density of the crystal and V1 is the volume of the crystal. V1=πr 2 ×L(2) where r is the radius of the crystal. Substitute formula (2) into formula (1) to obtain the mass of the crystal. S420. According to the law of conservation of mass, the mass before and after the crystal melts does not change. Therefore, the volume V2 of the crystal after melting is: V2 = M÷ρ2 where ρ2 is the density of the single crystal silicon after melting; M is obtained from S410. S430. According to the inner diameter size of the crucible, the rising height h of the liquid surface after the crystal remelting is completed can be calculated as: h= V2÷(πR 2 ) where R is the inner diameter of the crucible, and V2 is obtained from S420.

5. The crystal growth late stage broken edge melting back process as claimed in claim 4, characterized in that: In S410, a caliper or a laser diameter gauge is used to measure the diameter of the crystal.

6. The crystal growth late stage broken edge melting back process as claimed in claim 1, characterized in that: The S400 specifically includes: S410. Calculate the mass of the crystal as: M = ρ1×V1 (1) where ρ1 is the density of the crystal and V1 is the volume of the crystal. V1=πR 2 ×△L(2) where R is the inner diameter of the crucible, and ΔL is the height difference of the liquid surface before and after the crystal enters the molten liquid in the crucible. According to Archimedes' law, the volume of the crystal below the liquid surface is the same as the volume of the liquid discharged after the crystal enters below the liquid surface. S420. According to the law of conservation of mass, the mass before and after the crystal melts does not change. Therefore, the volume V2 of the crystal after melting is: V2 = M÷ρ2 Wherein, ρ2 is the density of single crystal silicon after melting; M is obtained from S410; S430, according to the inner diameter of the crucible, the height h of the liquid level after the crystal is melted back can be calculated as: h= V2÷(πR 2 ) Wherein, R is the inner diameter of the crucible, and V2 is obtained by the S420.

7. The crystal growth late stage broken edge melting back process as claimed in claim 1, characterized in that: In the S800, when the weight of the solid crystal is detected to be zero, it indicates that the crystal has been completely melted back.

8. The crystal growth late stage broken edge melting back process as claimed in claim 7, characterized in that: In the S800, a quality detector is arranged in the furnace, and the quality detector is communicatively connected with the alarm. The quality detector is used to detect the quality of the solid crystal. When the quality detector detects that the quality of the solid crystal is zero, the alarm emits a sound wave and / or light wave alarm.

9. The crystal growth late stage broken edge melting back process as claimed in claim 1, characterized in that: In the S200, a distance detector is used to monitor the liquid port distance in real time. In the S300, the distance detector is used to detect that the distance L between the bottom end of the crystal and the liquid surface is.

10. The crystal growth late stage broken edge melting back process as claimed in claim 1, characterized in that: In the S100 and S200, a lifting device is provided at the bottom of the crucible, and the lifting device is used to adjust the height of the crucible.

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