Monocrystalline silicon rod drawing method and system based on dynamic parameter linkage

Abstract

The invention provides a single crystal silicon rod drawing method and system based on dynamic parameter linkage, and the method comprises the steps: implementing a temperature gradient dynamic control strategy according to different stages of single crystal silicon rod drawing; a linkage strategy of a rotation rate and a pulling speed is adopted, and the rotation rate of the seed crystal is kept at a high rotation speed in the initial stage of pulling to stabilize a melt interface; meanwhile, a stepped dynamic adjustment strategy is adopted for the lifting speed, low-speed lifting is kept in the initial stage so as to ensure the melt stability, and then the lifting speed is linearly increased according to the increase of the diameter of the silicon rod; and the crucible lifting speed is adjusted in real time based on a self-adaptive adjustment strategy, so that the crucible lifting speed and the increase of the diameter of the silicon rod are kept synchronous, the stability of the melt liquid level height is maintained, and the fluctuation of the dopant concentration is prevented. By dynamically adjusting the temperature gradient, the rotation rate, the pulling speed and the crucible lifting speed, thermal stress is reduced, melt convection is stabilized, the radial uniformity of the silicon wafer is improved, and the requirements of a BC battery for low-defect and high-uniformity doping are met.

Description

Technical Field

[0001] This invention relates to the field of monocrystalline silicon rod pulling technology, specifically to a method and system for pulling monocrystalline silicon rods based on dynamic parameter linkage, which is particularly suitable for adapting to the requirements of BC cells (back contact cells) for highly uniform doping and low defects in monocrystalline silicon wafers. Background Technology

[0002] Currently, monocrystalline silicon ingot pulling technology is a crucial link in the solar photovoltaic industry, and its product quality directly affects the performance and efficiency of subsequent solar cells. Traditional monocrystalline silicon ingot pulling technology mainly adopts static parameter control and a staged independent adjustment strategy. During the pulling process, parameters such as temperature field, rotation rate, and pulling power are independently controlled, which cannot dynamically respond to changes in thermal stress during crystal growth. This leads to fluctuations in radial doping concentration of the silicon wafer (resistivity range >5%) and high dislocation density (>200 / cm²), making it difficult to meet the requirements of BC cells for low defect and highly uniform doping.

[0003] The existing technology has the following drawbacks: Fixed temperature control: The heating rate is fixed throughout the process, which leads to local overheating during seed crystal fusion, causing cracks in the silicon wafer and a defect density as high as 200 / cm².

[0004] The parameters operate independently: parameters such as pulling speed and rotation rate are adjusted independently, resulting in chaotic melt convection, uneven distribution of dopants, and resistivity fluctuations of up to 5%.

[0005] The crucible lifting process is crude: a fixed speed can easily cause liquid surface fluctuations, contaminating the tail of the silicon wafer and increasing the defect rate by 10%.

[0006] Especially for BC cells, the uniformity of silicon wafer doping concentration is extremely important, requiring a uniformity of ±3%, which traditional processes cannot meet. Therefore, developing a single-crystal silicon rod pulling method and system that can dynamically respond to the crystal growth process and achieve parameter linkage control is particularly important. Summary of the Invention

[0007] The main objective of this invention is to provide a method and system for pulling single-crystal silicon rods based on dynamic parameter linkage. By dynamically adjusting the temperature gradient, rotation rate, pulling speed, and crucible lifting speed, thermal stress is reduced, melt convection is stabilized, and the radial uniformity of the silicon wafer is improved, thus meeting the requirements of BC cells for low defect and high uniform doping.

[0008] The present invention achieves the above objectives through the following technical solutions: A method for pulling single-crystal silicon rods based on dynamic parameter linkage, comprising: According to the different stages of single crystal silicon rod pulling, a dynamic temperature gradient control strategy is implemented. Specifically, in the early stage of seed crystal fusion, the temperature of the top of the hot zone is rapidly increased to the preset value while the bottom temperature is kept constant. When the diameter of the silicon rod reaches the preset proportion of the target size, the gradient cooling program is started to refine the grains. A linkage strategy of rotation rate and pulling speed is adopted. The seed crystal rotation rate is kept at a high speed in the early stage of pulling to stabilize the melt interface, and the rotation rate is reduced in the stable growth stage to reduce crystal edge defects. At the same time, the pulling speed adopts a step-type dynamic adjustment strategy. In the initial stage, the pulling speed is kept at a low speed to ensure melt stability, and then the pulling speed is linearly increased according to the increase of silicon rod diameter to match the melt volume change and maintain the stability of the pulling process. The crucible lifting speed is adjusted in real time based on an adaptive adjustment strategy to keep the crucible lifting speed synchronized with the increase in the diameter of the silicon rod, so as to maintain the stability of the melt level and prevent fluctuations in the dopant concentration.

[0009] According to the single-crystal silicon rod pulling method based on dynamic parameter linkage provided by the present invention, in the initial stage of seed crystal fusion, the temperature rise rate K ranges from 8 to 10℃ / s. The heating power is dynamically adjusted by the difference between the top temperature T1 of the thermal field and the initial temperature T0, which is collected in real time. To ensure rapid heating during the welding stage and avoid thermal shock; When the diameter of the silicon rod reaches 20% of the target size, the axial temperature gradient is dynamically calculated using the following formula:

[0010] in, T 0 represents the temperature at the top of the thermal field when the seed crystal just comes into contact with the melt during the single-crystal silicon rod pulling process. T 1 represents the real-time temperature at the top of the thermal field, collected in real time via thermocouples. T 2. To maintain the stability of the melt, the bottom temperature of the thermal field. D The real-time diameter of a single-crystal silicon rod is monitored online using a CCD vision system or a laser diameter gauge.

[0011] According to the present invention, a method for pulling single-crystal silicon rods based on dynamic parameter linkage is provided. When the diameter D increases, the axial temperature gradient T is dynamically reduced, the cooling rate is automatically slowed down, the heat dissipation efficiency is reduced due to the increase in crystal size, and lattice distortion caused by local overcooling is avoided. The diameter D is monitored online at a predetermined sampling frequency using a CCD vision system or a laser diameter gauge, and the data is fed back to the control unit in real time for dynamic recalculation of the target temperature gradient value. When the real-time rate of change of diameter D exceeds the preset threshold, the closed-loop control of temperature gradient adjustment is triggered to adjust the heating power at the top of the hot field or the cooling rate at the bottom to ensure that the T gradient is synchronously adapted to the diameter growth. Set a lower limit for the temperature gradient to prevent dislocation multiplication caused by an excessively large diameter D leading to an excessively low T gradient and insufficient melt undercooling. By combining the real-time value of diameter D with the target temperature gradient curve, a gradient cooling buffer segment is dynamically inserted. When the diameter reaches 50%~80% of the target size, the cooling rate is reduced in stages to further optimize the grain growth orientation.

[0012] According to the present invention, a method for pulling single-crystal silicon rods based on dynamic parameter linkage is provided. In the linkage strategy between rotation rate and pulling speed, the seed crystal rotation rate adopts a segmented dynamic adjustment strategy, specifically including: Segmented control logic: Initial high-speed control: When the real-time diameter D of the single crystal silicon rod is less than 20 mm, the seed crystal rotation speed is set to 10 rpm. Rapid rotation suppresses melt turbulence and accelerates the formation of a stable melt-crystal interface. Low rotation speed control during the stabilization period: When the real-time diameter D of the single crystal silicon rod is ≥ 20 mm, the seed crystal rotation speed is reduced to 5 rpm to reduce the interference of centrifugal force on melt flow and reduce crystal edge dislocations and slip defects. The seed crystal rotation rate R is dynamically selected according to the following formula:

[0013] The rotation rate is switched by real-time monitoring of the diameter D to ensure melt stability during process transitions.

[0014] According to the present invention, a method for pulling single-crystal silicon rods based on dynamic parameter linkage is provided, wherein the pulling speed adopts a step-type dynamic adjustment strategy and is matched with the real-time diameter D of the single-crystal silicon rod and the change in melt volume, specifically including: Stepped speed control logic: Initial stage: The lifting speed is set to the base value of 0.1 mm / min; Stable growth stage: After the diameter of the single crystal silicon rod tends to stabilize, the pulling speed is increased to the range of 0.3~0.5 mm / min, and is adjusted in real time through dynamic compensation to match the requirements of melt volume change; The lifting speed V is calculated in real time according to the following formula:

[0015] Among them, D 实时 D represents the current diameter of the single-crystal silicon rod obtained through an online monitoring system. 目标 The target diameter value is preset; the dynamic compensation term is... It increases linearly with the diameter, ensuring that the pulling rate is synchronized with the expansion of the crystal cross-sectional area.

[0016] According to the present invention, a method for pulling single-crystal silicon rods based on dynamic parameter linkage is provided, wherein the crucible lifting speed implements an adaptive dynamic adjustment strategy, specifically including: Crucible lifting speed V The crucible is calculated in real time using the following formula: V Crucible = Basic velocity component + Dynamic compensation component The base velocity component is 0.5 mm / min to ensure the basic supply demand of the melt, and the dynamic compensation component is... k D It increases linearly with the increase of diameter. D The real-time diameter of the single-crystal silicon rod. k This is the proportionality coefficient.

[0017] The present invention provides a method for pulling single-crystal silicon rods based on dynamic parameter linkage, based on the formula: melt volume ∝ silicon rod cross-sectional area = π(D / 2). 2 The proportional relationship, through diameter D 实时 Feedback adjustment of the lifting speed compensates for the increased melt consumption caused by the increased diameter, and maintains a stable melt level. The linkage strategy of rotation rate and lifting speed, the dynamic control strategy of temperature gradient and the adaptive adjustment strategy of crucible lifting speed are linked to form a four-parameter closed-loop control system. Through diameter D Online monitoring triggers synchronous adjustment of the crucible lifting speed; When the diameter reaches 50% of the target size, the synchronous adjustment of the pulling speed and gradient cooling is triggered to avoid lattice defects caused by the mismatch between the cooling rate and the pulling rate.

[0018] A single-crystal silicon rod pulling system based on dynamic parameter linkage, characterized in that it includes: The temperature gradient dynamic control module is used to implement the above-mentioned temperature gradient dynamic control strategy. The rotation rate and lifting speed linkage module is used to implement the above-mentioned linkage strategy between rotation rate and lifting speed. The crucible lifting speed adaptive adjustment module is used to implement the above-mentioned adaptive adjustment strategy for crucible lifting speed; The data acquisition and processing module is used to collect parameters in real time, including at least the thermal field temperature and the diameter of the single crystal silicon rod, and transmit them to each control module to achieve dynamic adjustment.

[0019] According to the present invention, a single-crystal silicon rod pulling system based on dynamic parameter linkage is provided. The data acquisition and processing module includes a ring heater thermocouple, a CCD vision system or a laser diameter measuring instrument, for real-time acquisition of the top temperature of the hot zone, the bottom temperature of the hot zone and the diameter of the single-crystal silicon rod.

[0020] According to the present invention, a single crystal silicon rod pulling system based on dynamic parameter linkage is provided. The system further includes a control unit for receiving parameters transmitted by a data acquisition and processing module. The parameters include at least one of temperature parameters, rotation rate parameters, pulling speed parameters, and crucible lifting speed parameters. The received parameters are calculated and processed, and the results of the calculated parameters are analyzed and judged. The analysis and judgment are based on the judgment rules set according to the specific requirements of each parameter at different stages in the material preparation process, including but not limited to at least one of parameter threshold judgment, parameter change trend judgment, and parameter synergy judgment. Output control commands to at least one of the following modules: temperature gradient dynamic control module, rotation rate and lifting speed linkage module, and crucible lifting speed adaptive adjustment module; Among them, the control commands output to the temperature gradient dynamic control module are used to adjust the temperature gradient during the preparation process so that the temperature parameters meet the preset requirements; the control commands output to the rotation rate and lifting speed linkage module are used to coordinate the rotation rate and lifting speed; and the control commands output to the crucible lifting speed adaptive adjustment module are used to adaptively adjust the crucible lifting speed according to the real-time state of material preparation, so as to achieve the linkage control of the four parameters of temperature, rotation rate, lifting speed and crucible lifting speed.

[0021] Therefore, compared with the prior art, the single-crystal silicon rod pulling method and system based on dynamic parameter linkage proposed in this invention has the following beneficial effects: 1. Significant thermal stress control: The temperature rise during the seed crystal fusion stage is greatly reduced, effectively avoiding dislocations caused by sudden temperature changes, and reducing the dislocation density from 200 / cm² in traditional processes. 2 Reduced to 80 / cm 2 This significantly improved the quality of the crystal.

[0022] 2. Significantly improved doping uniformity: By stabilizing melt convection, the uniform diffusion of dopants (such as boron) is ensured, and the boron diffusion concentration difference is optimized from 5% in the traditional process to ≤3%, which perfectly meets the high-precision contact requirements of the back electrode of BC battery.

[0023] 3. Adaptable to large-size silicon wafer pulling: The system supports the pulling of large-size silicon wafers (such as G12). Through the adaptive algorithm of crucible lifting speed, the crucible lifting speed is dynamically adjusted according to the real-time diameter of the silicon rod to maintain the stability of the melt height, reduce manual intervention, and improve production efficiency and product consistency.

[0024] 4. Enhanced melt stability: The strategy of linking rotation speed and pulling speed is adopted. In the initial stage, high-speed rotation suppresses melt turbulence, and in the stable period, low-speed rotation reduces the disturbance of centrifugal force on the melt. At the same time, the stepwise increase of the pulling speed matches the change of melt volume, which significantly improves the melt stability and reduces the dopant concentration fluctuation to 2%.

[0025] 5. Improved battery efficiency: The phased speed adjustment significantly reduces dislocation density and metallization recombination losses, thereby greatly improving the efficiency of BC cells and further enhancing the power generation performance and market competitiveness of photovoltaic products.

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0027] Figure 1 This is a flowchart of an embodiment of a single-crystal silicon rod pulling method based on dynamic parameter linkage according to the present invention.

[0028] Figure 2 This is a schematic diagram of an embodiment of a single-crystal silicon rod pulling system based on dynamic parameter linkage according to the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0030] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0031] An embodiment of a method for pulling single-crystal silicon rods based on dynamic parameter linkage See Figure 1 This embodiment provides a method for pulling single-crystal silicon rods based on dynamic parameter linkage, including: Step S1: Implement a dynamic temperature gradient control strategy according to different stages of single crystal silicon rod pulling. Specifically, in the early stage of seed crystal fusion, rapidly increase the temperature of the top of the hot zone to a preset value while keeping the bottom temperature constant; when the diameter of the silicon rod reaches a preset proportion of the target size, start the gradient cooling program to refine the grains. Step S2 employs a linkage strategy between rotation speed and pulling speed. The seed crystal rotation speed is kept at a high speed in the early stage of pulling to stabilize the melt interface, and the rotation speed is reduced in the stable growth stage to reduce crystal edge defects. At the same time, the pulling speed adopts a step-type dynamic adjustment strategy. In the initial stage, the pulling speed is kept at a low speed to ensure melt stability, and then the pulling speed is linearly increased according to the increase of silicon rod diameter to match the melt volume change and maintain the stability of the pulling process. Step S3: Adjust the crucible lifting speed in real time based on an adaptive adjustment strategy to keep the crucible lifting speed synchronized with the increase in the diameter of the silicon rod, so as to maintain the stability of the melt level and prevent fluctuations in the dopant concentration.

[0032] In step S1 above, during the initial stage of seed crystal fusion, the temperature rise rate K ranges from 8 to 10℃ / s. The heating power is dynamically adjusted based on the real-time difference between the top temperature T1 of the thermal field and the initial temperature T0. To ensure rapid heating during the welding stage and avoid thermal shock; When the diameter of the silicon rod reaches 20% of the target size, the axial temperature gradient is dynamically calculated using the following formula:

[0033] in, T 1 represents the real-time temperature at the top of the thermal field, collected in real time via thermocouples. T 2. The bottom temperature of the thermal field is a constant value set to maintain melt stability (usually 1420±5℃). D The real-time diameter of a single-crystal silicon rod is monitored online using a CCD vision system or a laser diameter gauge. T 0 represents the temperature at the top of the thermal field when the seed crystal first contacts the melt during the single-crystal silicon rod pulling process. As the starting point for dynamically adjusting the temperature gradient, ensuring rapid heating in the initial stage of fusion (to avoid thermal shock) has a crucial impact on crystal quality: if T If T0 is too high, it may cause the melt to overheat and the dislocation density to increase; if T0 is too low, the welding time will be prolonged and the efficiency will be reduced.

[0034] As can be seen, the above formula essentially calculates the axial temperature gradient (unit: ℃ / mm) dynamically. By introducing the diameter D as a denominator parameter, it achieves dynamic adjustment of "the larger the diameter, the gentler the temperature gradient," thus compensating for the influence of melt volume changes on the temperature field. In the initial stage of seed crystal fusion: rapidly increase the temperature at the top of the thermal field ( T=8~10 ℃ / s), accelerate seed crystal fusion, but keep the bottom temperature constant (avoid overheating); when the silicon rod diameter reaches 20% of the target size, start gradient cooling (top cooling rate 5℃ / min, bottom remains stable) to refine the grains.

[0035] For example: If the initial temperature T0 = 1450°C, and the top temperature increases at a rate of ΔT = 10°C / s during the welding stage, then the top temperature after t seconds is: T1 = 1450 + 10 t.

[0036] As the diameter D increases, the axial temperature gradient T is dynamically reduced by increasing the denominator D in the above formula, automatically slowing down the cooling rate, compensating for the decrease in heat dissipation efficiency caused by the increase in crystal size, and avoiding lattice distortion caused by local overcooling. The diameter D is monitored online using a CCD vision system or a laser diameter gauge at a predetermined sampling frequency (≥10Hz), and the data is fed back to the control unit in real time for dynamic recalculation of the target temperature gradient value. When the real-time rate of change of diameter D exceeds the preset threshold (e.g., ±0.1 mm / s), the closed-loop control of temperature gradient adjustment is triggered to adjust the heating power at the top of the hot field or the cooling rate at the bottom, ensuring that the T gradient is synchronously adapted to the diameter growth. Set a lower limit for the temperature gradient (e.g., 0.5℃ / mm) to prevent dislocation multiplication caused by an excessively large diameter D leading to an excessively low temperature gradient and insufficient melt undercooling. By combining the real-time value of diameter D with the target temperature gradient curve, a gradient cooling buffer segment is dynamically inserted. When the diameter reaches 50%~80% of the target size, the cooling rate is reduced in stages to further optimize the grain growth orientation.

[0037] It is evident that as the crystal diameter increases, the specific surface area decreases, leading to a reduction in heat dissipation efficiency. The above formula automatically slows down the cooling rate and avoids lattice distortion by increasing D → increasing the denominator → decreasing the gradient T.

[0038] In step S2 above, the seed crystal rotation rate of the linkage strategy between rotation rate and pulling speed adopts a segmented dynamic adjustment strategy, specifically including: Segmented control logic: Initial high-speed control: When the real-time diameter D of the single crystal silicon rod is less than 20 mm, the seed crystal rotation speed is set to 10 rpm. Rapid rotation suppresses melt turbulence and accelerates the formation of a stable melt-crystal interface. Low rotation speed control during the stabilization period: When the real-time diameter D of the single crystal silicon rod is ≥ 20 mm, the seed crystal rotation speed is reduced to 5 rpm to reduce the interference of centrifugal force on melt flow and reduce crystal edge dislocations and slip defects. The seed crystal rotation rate R is dynamically selected according to the following formula:

[0039] The rotation rate is switched by real-time monitoring of the diameter D to ensure melt stability during process transitions.

[0040] In this embodiment, the pulling speed adopts a step-type dynamic adjustment strategy and is matched with the real-time diameter D of the single crystal silicon rod and the change in melt volume, specifically including: Stepped speed control logic (initial 0.1 mm / min → stabilized 0.3-0.5 mm / min) to match melt volume changes: Initial stage: The pulling speed is set to the base value of 0.1 mm / min: to ensure that the melt level drops slowly and to avoid a sudden drop in dopant concentration caused by a sudden decrease in melt volume; Stable growth stage: After the diameter of the single crystal silicon rod tends to stabilize, the pulling speed is increased to the range of 0.3~0.5 mm / min, and is adjusted in real time through dynamic compensation to match the requirements of melt volume change; The lifting speed V is calculated in real time according to the following formula:

[0041] Among them, D 实时 D represents the current diameter of the single-crystal silicon rod obtained through an online monitoring system. 目标 The target diameter value is preset; the dynamic compensation term is... It increases linearly with the diameter, ensuring that the pulling rate is synchronized with the expansion of the crystal cross-sectional area.

[0042] Based on the formula: melt volume ∝ silicon rod cross-sectional area = π(D / 2) 2 The proportional relationship, through diameter D 实时 Feedback adjustment of the lifting speed compensates for the increased melt consumption caused by the increase in diameter, maintains a stable melt level, matches the change in melt volume, and reduces dopant concentration fluctuation to 2%; the above formula automatically adapts to different target diameters (e.g., D target = 300 mm for G12 silicon wafers) without the need for manual parameter adjustment.

[0043] Thermal and flow field balance: The initial high speed (10 rpm) is combined with rapid heating (ΔT=10°C / s) to accelerate seed crystal welding and shorten the process time; the low speed stabilization period (5 rpm) is combined with gradient cooling (5°C / min at the top) to refine the grains and reduce oxygen precipitates.

[0044] BC battery process compatibility: Radial uniformity: The lifting speed is linked to the diameter ratio to ensure that the boron diffusion concentration difference is ≤3%, which meets the requirements for the consistency of the contact resistance of the back electrode; Defect control: Staged speed adjustment makes the dislocation density ≤80 / cm², reduces metallization recombination loss, and improves battery efficiency by 0.2%.

[0045] In step S3 above, the crucible lifting speed is subject to an adaptive dynamic adjustment strategy, specifically including: Crucible lifting speedV The crucible is calculated in real time using the following formula: V Crucible = Basic velocity component + Dynamic compensation component The base velocity component is 0.5 mm / min to ensure the basic supply demand of the melt, and the dynamic compensation component is... k D It increases linearly with the increase of diameter. D The real-time diameter of the single-crystal silicon rod. k With a proportionality coefficient of 0.1, the crucible lifting speed increases linearly with the increase of the silicon rod diameter.

[0046] In this embodiment, the linkage strategy of rotation speed and lifting speed (10rpm→5rpm), the dynamic control strategy of temperature gradient (8~10℃ / s→gradient cooling) and the adaptive adjustment strategy of crucible lifting speed (V0+k·D) are linked to form a four-parameter closed-loop control system. Through diameter D Online monitoring triggers synchronous adjustment of the crucible lifting speed; When the diameter reaches 50% of the target size, the synchronous adjustment of the pulling speed and gradient cooling is triggered to avoid lattice defects caused by the mismatch between the cooling rate and the pulling rate.

[0047] For example, when the diameter of the silicon rod D = 50 mm, the crucible speed = 0.5 + 0.1 × 50 = 5.5 mm / min; when D = 100 mm, the crucible speed = 0.5 + 0.1 × 100 = 10.5 mm / min.

[0048] An embodiment of a single-crystal silicon rod pulling system based on dynamic parameter linkage like Figure 2 As shown, this embodiment provides a single-crystal silicon rod pulling system based on dynamic parameter linkage, comprising: The temperature gradient dynamic control module is used to implement the above-mentioned temperature gradient dynamic control strategy. The rotation rate and lifting speed linkage module is used to implement the above-mentioned linkage strategy between rotation rate and lifting speed. The crucible lifting speed adaptive adjustment module is used to implement the above-mentioned adaptive adjustment strategy for crucible lifting speed; The data acquisition and processing module is used to collect parameters in real time, including at least the thermal field temperature and the diameter of the single crystal silicon rod, and transmit them to each control module to achieve dynamic adjustment.

[0049] According to the present invention, a single-crystal silicon rod pulling system based on dynamic parameter linkage is provided. The data acquisition and processing module includes a ring heater thermocouple, a CCD vision system or a laser diameter measuring instrument, which are used to acquire the top temperature of the hot zone, the bottom temperature of the hot zone and the diameter of the single-crystal silicon rod in real time.

[0050] According to the present invention, a single crystal silicon rod pulling system based on dynamic parameter linkage is provided. The system further includes a control unit for receiving parameters transmitted by a data acquisition and processing module. The parameters include at least one of temperature parameters, rotation rate parameters, pulling speed parameters, and crucible lifting speed parameters. The received parameters are calculated and processed, and the results of the calculation and processing are analyzed and judged. The analysis and judgment are based on the judgment rules set according to the specific requirements of each parameter at different stages of the material preparation process, including but not limited to at least one of parameter threshold judgment, parameter change trend judgment, and parameter synergy judgment. Output control commands to at least one of the following modules: temperature gradient dynamic control module, rotation rate and lifting speed linkage module, and crucible lifting speed adaptive adjustment module; Among them, the control commands output to the temperature gradient dynamic control module are used to adjust the temperature gradient during the preparation process so that the temperature parameters meet the preset requirements; the control commands output to the rotation rate and lifting speed linkage module are used to coordinate the rotation rate and lifting speed; and the control commands output to the crucible lifting speed adaptive adjustment module are used to adaptively adjust the crucible lifting speed according to the real-time state of material preparation, so as to achieve the linkage control of the four parameters of temperature, rotation rate, lifting speed and crucible lifting speed.

[0051] In summary, the single-crystal silicon rod pulling method and system based on dynamic parameter linkage proposed in this invention have the following advantages: Significant improvement in thermal stress control: The temperature rise during the seed crystal fusion stage is greatly reduced, effectively avoiding dislocations caused by sudden temperature changes, and lowering the dislocation density from 200 / cm² in traditional processes. 2 Reduced to 80 / cm 2 This significantly improved the quality of the crystal.

[0052] Significantly improved doping uniformity: By stabilizing melt convection, dopants (such as boron) are ensured to diffuse uniformly, and the boron diffusion concentration difference is optimized from 5% in traditional processes to ≤3%, perfectly meeting the high-precision contact requirements of the back electrode of BC batteries.

[0053] Adapted for large-size silicon wafer pulling: The system supports the pulling of large-size silicon wafers (such as G12). Through an adaptive crucible lifting speed algorithm, the system dynamically adjusts the crucible lifting speed according to the real-time diameter of the silicon rod, maintaining a stable melt height, reducing manual intervention, and improving production efficiency and product consistency.

[0054] Enhanced melt stability: A strategy linking rotation speed and pulling speed is adopted. High-speed rotation in the early stage suppresses melt turbulence, and low-speed rotation in the stable period reduces the disturbance of centrifugal force on the melt. At the same time, the stepwise increase of the pulling speed matches the change of melt volume, which significantly improves melt stability and reduces dopant concentration fluctuation to 2%.

[0055] Improved battery efficiency: Staged speed adjustment significantly reduces dislocation density and metallization recombination losses, thereby greatly improving the efficiency of BC cells and further enhancing the power generation performance and market competitiveness of photovoltaic products.

[0056] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for pulling single-crystal silicon rods based on dynamic parameter linkage, characterized in that, include: According to the different stages of single crystal silicon rod pulling, a dynamic temperature gradient control strategy is implemented. Specifically, in the early stage of seed crystal fusion, the temperature of the top of the hot zone is rapidly increased to the preset value while the bottom temperature is kept constant. When the diameter of the silicon rod reaches the preset proportion of the target size, the gradient cooling program is started to refine the grains. A linkage strategy of rotation rate and pulling speed is adopted. The seed crystal rotation rate is kept at a high speed in the early stage of pulling to stabilize the melt interface, and the rotation rate is reduced in the stable growth stage to reduce crystal edge defects. At the same time, the pulling speed adopts a step-type dynamic adjustment strategy. In the initial stage, the pulling speed is kept at a low speed to ensure melt stability, and then the pulling speed is linearly increased according to the increase of silicon rod diameter to match the melt volume change and maintain the stability of the pulling process. The crucible lifting speed is adjusted in real time based on an adaptive adjustment strategy to keep the crucible lifting speed synchronized with the increase in the diameter of the silicon rod, so as to maintain the stability of the melt level and prevent fluctuations in the dopant concentration.

2. The method according to claim 1, characterized in that: In the initial stage of seed crystal fusion, the temperature rise rate K ranges from 8 to 10℃ / s. The heating power is dynamically adjusted by the difference between the top temperature T1 of the thermal field and the initial temperature T0, which is collected in real time. To ensure rapid heating during the welding stage and avoid thermal shock; When the diameter of the silicon rod reaches 20% of the target size, the axial temperature gradient is dynamically calculated using the following formula: in, T 0 represents the temperature at the top of the thermal field when the seed crystal just comes into contact with the melt during the single-crystal silicon rod pulling process. T 1 represents the real-time temperature at the top of the thermal field, collected in real time via thermocouples. T 2. To maintain the stability of the melt, the bottom temperature of the thermal field. D The real-time diameter of a single-crystal silicon rod is monitored online using a CCD vision system or a laser diameter gauge.

3. The method according to claim 2, characterized in that: As the diameter D increases, the axial temperature gradient T is dynamically reduced, the cooling rate is automatically slowed down, the heat dissipation efficiency is compensated for by the increase in crystal size, and lattice distortion caused by local overcooling is avoided. The diameter D is monitored online at a predetermined sampling frequency using a CCD vision system or a laser diameter gauge, and the data is fed back to the control unit in real time for dynamic recalculation of the target temperature gradient value. When the real-time rate of change of diameter D exceeds the preset threshold, the closed-loop control of temperature gradient adjustment is triggered to adjust the heating power at the top of the hot field or the cooling rate at the bottom to ensure that the T gradient is synchronously adapted to the diameter growth. Set a lower limit for the temperature gradient to prevent dislocation multiplication caused by an excessively large diameter D leading to an excessively low T gradient and insufficient melt undercooling. By combining the real-time value of diameter D with the target temperature gradient curve, a gradient cooling buffer segment is dynamically inserted. When the diameter reaches 50%~80% of the target size, the cooling rate is reduced in stages to further optimize the grain growth orientation.

4. The method according to claim 1, characterized in that: In the linkage strategy between rotation rate and pulling speed, the seed crystal rotation rate adopts a segmented dynamic adjustment strategy, specifically including: Segmented control logic: Initial high-speed rotation control: When the real-time diameter D of the single crystal silicon rod is less than 20 mm, the seed crystal rotation speed is set to 10 rpm. Rapid rotation suppresses melt turbulence and accelerates the formation of a stable melt-crystal interface. Low rotation speed control during the stabilization period: When the real-time diameter D of the single crystal silicon rod is ≥ 20 mm, the seed crystal rotation speed is reduced to 5 rpm to reduce the interference of centrifugal force on melt flow and reduce crystal edge dislocations and slip defects. The seed crystal rotation rate R is dynamically selected according to the following formula: The rotation rate is switched by real-time monitoring of the diameter D to ensure melt stability during process transitions.

5. The method according to claim 1, characterized in that, The pulling speed adopts a step-by-step dynamic adjustment strategy and is matched with the real-time diameter D of the single crystal silicon rod and the change in melt volume, specifically including: Stepped speed control logic: Initial stage: The lifting speed is set to the base value of 0.1 mm / min; Stable growth stage: After the diameter of the single crystal silicon rod tends to stabilize, the pulling speed is increased to the range of 0.3~0.5 mm / min, and is adjusted in real time through dynamic compensation to match the requirements of melt volume change; The lifting speed V is calculated in real time according to the following formula: Among them, D 实时 D represents the current diameter of the single-crystal silicon rod obtained through an online monitoring system. 目标 The target diameter value is preset; the dynamic compensation term is... It increases linearly with the diameter, ensuring that the pulling rate is synchronized with the expansion of the crystal cross-sectional area.

6. The method according to claim 1, characterized in that, The crucible lifting speed is subject to an adaptive dynamic adjustment strategy, specifically including: Crucible lifting speed V The crucible is calculated in real time using the following formula: V Crucible = Basic velocity component + Dynamic compensation component The base velocity component is 0.5 mm / min to ensure the basic supply demand of the melt, and the dynamic compensation component is... k D It increases linearly with the increase of diameter. D The real-time diameter of the single-crystal silicon rod. k This is the proportionality coefficient.

7. The method according to claim 5 or 6, characterized in that: Based on the formula: melt volume ∝ silicon rod cross-sectional area = π(D / 2) 2 The proportional relationship, through diameter D 实时 Feedback adjustment of the lifting speed compensates for the increased melt consumption caused by the increased diameter, and maintains a stable melt level. The linkage strategy of rotation rate and lifting speed, the dynamic control strategy of temperature gradient and the adaptive adjustment strategy of crucible lifting speed are linked to form a four-parameter closed-loop control system. Through diameter D Online monitoring triggers synchronous adjustment of the crucible lifting speed; When the diameter reaches 50% of the target size, the synchronous adjustment of the pulling speed and gradient cooling is triggered to avoid lattice defects caused by the mismatch between the cooling rate and the pulling rate.

8. A single-crystal silicon rod pulling system based on dynamic parameter linkage, characterized in that, include: A temperature gradient dynamic control module is used to implement the temperature gradient dynamic control strategy as described in claim 1. A rotation rate and lifting speed linkage module is used to implement the rotation rate and lifting speed linkage strategy as described in claim 1. An adaptive adjustment module for crucible lifting speed is used to implement the adaptive adjustment strategy for crucible lifting speed as described in claim 1; The data acquisition and processing module is used to collect parameters in real time, including at least the thermal field temperature and the diameter of the single crystal silicon rod, and transmit them to each control module to achieve dynamic adjustment.

9. The system according to claim 8, characterized in that: The data acquisition and processing module includes a ring heater thermocouple, a CCD vision system or a laser diameter measuring instrument, used to acquire the top temperature of the hot zone, the bottom temperature of the hot zone and the diameter of the single crystal silicon rod in real time.

10. The system according to claim 8, characterized in that: The system also includes a control unit for receiving parameters transmitted by the data acquisition and processing module, the parameters including at least one of temperature parameters, rotation rate parameters, lifting speed parameters, and crucible lifting speed parameters; The received parameters are calculated and processed, and the results of the calculated parameters are analyzed and judged. The analysis and judgment are based on the judgment rules set according to the specific requirements of each parameter at different stages of the material preparation process, including but not limited to at least one of parameter threshold judgment, parameter change trend judgment, and parameter synergy judgment. Output control commands to at least one of the following modules: temperature gradient dynamic control module, rotation rate and lifting speed linkage module, and crucible lifting speed adaptive adjustment module; Among them, the control commands output to the temperature gradient dynamic control module are used to adjust the temperature gradient during the preparation process so that the temperature parameters meet the preset requirements; the control commands output to the rotation rate and lifting speed linkage module are used to coordinate the rotation rate and lifting speed; and the control commands output to the crucible lifting speed adaptive adjustment module are used to adaptively adjust the crucible lifting speed according to the real-time state of material preparation, so as to achieve the linkage control of the four parameters of temperature, rotation rate, lifting speed and crucible lifting speed.

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