A method and system for controlling growth of a silicon ingot and a silicon ingot

Abstract

The application relates to the technical field of crystal growth, in particular to a silicon ingot growth control method and system and a silicon ingot. The silicon ingot growth control method is suitable for a silicon ingot, the silicon ingot is provided with a seed crystal chuck, and a heating piece is arranged in the seed crystal chuck; the silicon ingot growth control method comprises the following steps: lowering a pulling head carrying a seed crystal; heating the seed crystal chuck and the seed crystal by the heating piece; and making the difference between the seed crystal temperature and the melting zone temperature less than 400-800 DEG C. Through preheating of the seed crystal, the technical effect of improving the growth quality of the silicon ingot is achieved.

Description

Technical Field

[0001] This application relates to the field of crystal growth technology, and in particular to a growth control method, system, and silicon core furnace for silicon core furnaces. Background Technology

[0002] Silicon cores are the core carriers for producing polycrystalline silicon using the modified Siemens process. Their quality directly determines the uniformity, crystal integrity, and core breakage rate of subsequent polycrystalline silicon deposition. The mainstream method for preparing silicon cores is the zone melting method, which uses a silicon core furnace. The zone melting method generates a narrow molten zone using a high-frequency induction coil, relying on the surface tension of the molten zone to purify and grow high-purity polycrystalline silicon rods into silicon cores. The resulting silicon cores have the advantages of high purity and low oxygen and carbon content, making them the preferred seed crystals for photovoltaic-grade polycrystalline silicon deposition.

[0003] In the existing technology, in the early stage of silicon core pulling, the seed crystal needs to be lowered to contact the molten zone through the pull head, so as to achieve crystal growth in the seed crystal. However, in the actual crystal growth process, the contact between the seed crystal and the molten zone after it is lowered is not sufficient, which will cause problems such as crystal orientation deviation and dislocation density difference, thus affecting the growth quality of silicon core.

[0004] Therefore, the technical problem with the existing technology is that the silicon core growth quality is poor. Summary of the Invention

[0005] This application provides a growth control method, system, and silicon core furnace for silicon core furnaces, which achieves the technical effect of improving the growth quality of silicon cores by preheating the seed crystal.

[0006] Firstly, this application provides a growth control method for a silicon core furnace, which adopts the following technical solution: A growth control method for a silicon core furnace, applicable to a silicon core furnace, wherein the silicon core furnace has a seed crystal chuck, and a heating element is disposed within the seed crystal chuck; the growth control method for the silicon core furnace includes: This causes the lifting head to descend while carrying the seed crystal. The heating element heats the seed crystal chuck and the seed crystal. The temperature difference between the seed crystal and the melting zone should be less than 400–800℃.

[0007] As a preferred option, the first set of parameters of the silicon core is collected; The actual growth rate of silicon cores is calculated based on the first set of parameters. The rate difference is calculated based on the actual growth rate of the silicon core and the mechanical pulling rate of the lifting head. Adjust the second parameter group so that the rate difference is within the threshold.

[0008] Preferably, the first parameter set includes: the bending deflection of the silicon core. Silicon core length ,diameter Axial tension Melting zone temperature and furnace temperature ; The second parameter group includes: seed crystal chuck temperature Melting zone heating power and the amount of hydrogen doping in the melting zone .

[0009] Preferably, the calculation of the actual silicon core growth rate based on the first parameter set includes: The bending deflection of the silicon core. Silicon core length ,diameter Axial tension Melting zone temperature and furnace temperature Regarding the actual growth rate of silicon cores The first function model; Based on the collected bending deflection of the silicon core Silicon core length ,diameter Axial tension Melting zone temperature and furnace temperature And the first function model, to determine the actual growth rate of silicon cores. .

[0010] Preferably, the first function model is:

[0011] in, The mechanical lifting speed of the lifting head; The coefficient representing the influence of bending stress on the growth rate; The elastic modulus of the silicon core; The moment of inertia of the silicon core cross section; This is the coefficient representing the influence of axial stress on the growth rate. This refers to the axial tensile force on the silicon core. This represents the cross-sectional area of ​​the silicon core. This is the coefficient representing the influence of melting zone temperature on growth rate; This is the melting point of silicon.

[0012] Preferably, adjusting the second parameter set such that the rate difference is within a threshold includes: Establish seed crystal chuck temperature Melting zone heating power and the amount of hydrogen doping in the melting zone Regarding the rate difference The second function model; Rate difference based on target The second function model is used to determine the seed crystal chuck temperature. Melting zone heating power and the amount of hydrogen doping in the melting zone .

[0013] Preferably, the second function model is:

[0014]

[0015] in, For constant terms; The coefficient for the first term of heating power; The coefficient of the quadratic term of the heating power; This refers to the heater power. The coefficient of the first term for hydrogen doping; The cross-term coefficient for hydrogen doping and undercooling; The amount of hydrogen component added to the cooling gas; This is the coefficient of the coupling term between the temperature and length of the clamp.

[0016] Preferably, adjusting the second parameter set such that the rate difference is within a threshold includes: Establish a constrained optimization objective function and solve for the optimal parameter, seed crystal chuck temperature, that minimizes the rate difference. Melting zone heating power and the amount of hydrogen doping in the melting zone ; The objective function to be optimized is .

[0017] Secondly, the growth control system for a silicon core furnace provided in this application adopts the following technical solution: A growth control system for a silicon core furnace includes: The acquisition module is used to acquire the first set of parameters of the silicon core; The calculation module is used to calculate the actual growth rate of the silicon core based on the first set of parameters, and to calculate the rate difference based on the actual growth rate of the silicon core and the mechanical pulling rate of the lifting head; and The feedback module is used to adjust the second parameter group so that the rate difference is within the threshold.

[0018] Thirdly, the silicon core furnace provided in this application adopts the following technical solution: A silicon core furnace, for performing the growth method described above, the silicon core furnace comprising: Furnace body; The pulling assembly includes a pulling head, on which a seed crystal chuck is independently provided for each silicon core. The seed crystal chuck is used to hold the seed crystal to simultaneously pull multiple silicon cores, and each seed crystal chuck is provided with an independently temperature-controlled heating element for independently adjusting the temperature of the corresponding seed crystal. The heating assembly, located inside the furnace, includes heaters independently configured and controlled for each silicon core, used to independently adjust the local temperature of the corresponding silicon core's molten zone; and The gas path assembly is located inside the furnace and includes a coaxial cooling gas pipe that is independently configured for each silicon core. The outlet of the cooling gas pipe faces the crystal growth interface of the corresponding silicon core. Each cooling gas pipe is connected to a hydrogen branch pipe with independent flow control for independently supplying hydrogen doping to the crystal growth interface of the corresponding silicon core.

[0019] In summary, this application includes at least one of the following beneficial technical effects: This application preheats the seed crystal chuck during the initial stage of crystal growth, raising the seed crystal temperature. This facilitates crystal growth in the molten zone on the seed crystal, reduces problems such as crystal orientation deviation and dislocation density differences, and improves the quality of silicon core growth. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the silicon core furnace described in this application; Figure 2 This is a schematic diagram of the crystal pulling state of the silicon core furnace described in this application; Figure 3 This is a flowchart of the first growth control method for the silicon core furnace described in this application; Figure 4 This is a schematic diagram of the heating assembly and gas path assembly of the silicon core furnace described in this application; Figure 5 This is a flowchart of the second growth control method for the silicon core furnace described in this application; Figure 6 This is a flowchart illustrating the calculation of the difference in actual growth rate of silicon cores in the growth control method of the silicon core furnace described in this application; Figure 7 This is a flowchart of the second parameter calculation in the growth control method of the silicon core furnace described in this application.

[0021] Explanation of reference numerals in the attached drawings: 100, furnace body; 200, lifting assembly; 210, lifting head; 220, seed crystal chuck; 230, seed crystal; 300, heating assembly; 310, heater; 400, gas path assembly; 410, cooling gas pipe; 500, silicon core; 600, raw material rod. Detailed Implementation

[0022] The serial numbers assigned to components in this document, such as "first" and "second," are used solely to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages). It should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used solely for the convenience of describing this application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0023] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0024] To better understand the above technical solutions, a detailed description of the technical solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit the scope of this application.

[0025] This application provides a method for controlling the growth of silicon core in a furnace. By independently heating the seed crystal 230, the temperature difference between the seed crystal 230 and the molten zone is reduced, which is beneficial to the stable growth of the silicon core 500. Figure 1 , 2 As shown, the silicon core furnace growth control method is applicable to silicon core furnaces, which have a seed crystal chuck 220, and heating elements are installed inside the seed crystal chuck 220; for example... Figure 3 As shown, the growth control method for silicon core furnaces includes: S1: Causes the lifting head 210 to descend, carrying the seed crystal 230; S2: The heating element heats the seed crystal chuck 220 and the seed crystal 230; S3: Make the difference between the seed crystal temperature 230 and the melting zone temperature less than 400-800℃.

[0026] Understandably, during the growth of silicon core 500 using the zone melting method, when the seed crystal 230, which has a lower temperature, is inserted into the molten zone at 1412°C, an instantaneous temperature difference exceeding 1000°C will occur. This massive thermal shock can cause the seed crystal 230 to crack and result in an excessively high initial dislocation density, leading to fluctuations in the growth rate of the silicon core 500 throughout the process. This application addresses this by equipping each seed crystal 230 with an independent heating unit to preheat it before insertion into the molten zone, thereby significantly reducing the temperature difference between the seed crystal 230 and the molten zone, reducing thermal shock at its source, and improving crystallization stability.

[0027] In one embodiment, such as Figure 4 As shown, each seed crystal 230 has an independent heating element built into its chuck, which can independently control the temperature of the seed crystal 230. The temperature control range covers room temperature to 600 degrees Celsius. The temperature of the seed crystal 230 can be flexibly adjusted according to the characteristics of each seed crystal 230 and the actual temperature of the melting zone. Ultimately, the temperature difference between the seed crystal 230 and the melting zone is controlled at 400-800℃, which greatly reduces the interference of thermal shock on the crystallization process and improves the initial stability of silicon core 500 growth. In this way, the success rate of seed crystal 230 fusion is greatly improved, the initial crystallization dislocation density is reduced by two orders of magnitude, and the difference in the initial growth rate of different silicon cores 500 is narrowed.

[0028] It should be noted that, as Figure 1 , 2 As shown, when pulling silicon cores 500 using the zone melting method, multiple silicon cores 500 are usually pulled simultaneously in one furnace using the same pulling head 210. The silicon cores 500 have a relatively thin diameter and can reach several meters in length. However, due to the combined influence of various factors in the furnace, the actual crystal growth rate of the multiple silicon cores 500 varies significantly. Meanwhile, the mechanical pulling speed of the pulling head 210 is uniform and fixed, which ultimately leads to the silicon cores 500 with a growth rate greater than the pulling speed being subjected to axial pressure, resulting in bending or even breakage.

[0029] Therefore, this application also provides a silicon chip 500 growth control method that calculates the actual growth rate by collecting growth state parameters, compares the rate difference to obtain feedback adjustment of control parameters, and forms a complete closed-loop control. Figure 5 As shown, it includes: T1: Collect the first set of parameters for silicon core 500; T2: Calculate the actual growth rate of silicon core 500 based on the first parameter set; T3: Calculate the rate difference based on the actual growth rate of silicon core 500 and the mechanical lifting rate of lifting head 210; T4: Adjust the second parameter group so that the rate difference is within the threshold.

[0030] Specifically, the first step is to collect the first set of parameters related to the growth state of silicon core 500 in real time to obtain the current real growth state of silicon core 500; The second step is to calculate the actual growth rate of each silicon core 500 based on the collected first parameter set using a pre-built first function model. The third step is to compare the actual growth rate of silicon core 500 with the mechanical lifting rate of lifting head 210, and calculate the difference in growth rate of each silicon core 500. The fourth step involves adjusting the second set of parameters related to the growth control of silicon core 500 based on the difference in growth rate through a pre-built second function model, thereby achieving independent adjustment of the growth rate of each silicon core 500.

[0031] This replaces the traditional extensive mode of manual observation and experience-based adjustment, and realizes fully automated closed-loop control from state perception to quantitative calculation and then to precise adjustment. It solves the problems of existing technologies being unable to quantitatively perceive the real growth rate and unable to adjust individual roots independently, which is conducive to the uniformity control of the growth rate of silicon core 500.

[0032] The first parameter group includes: the bending deflection of silicon core 500. 500mm silicon core length ,diameter Axial tension Melting zone temperature and furnace temperature ; The second parameter set includes: seed crystal chuck temperature 220°C. Melting zone heating power and the amount of hydrogen doping in the melting zone .

[0033] The first parameter group consists of measurable parameters reflecting the current growth state of silicon core 500, specifically including the bending deflection of silicon core 500, the free length of silicon core 500, the real-time diameter of silicon core 500, the axial tensile force of silicon core 500, and the temperature at the center of the molten zone. All of the above parameters can be acquired in real time by non-contact sensors or built-in micro sensors without entering the high-temperature molten zone. The acquisition process will not interfere with the normal growth of silicon core 500 and can accurately reflect the stress, deformation, and thermal state of silicon core 500, providing reliable input data for the calculation of the actual growth rate. For example, the bending deflection and diameter of the silicon core 500 can be acquired by an industrial camera through an observation window to capture the outline of the silicon core 500, and the deflection and diameter can be calculated by an edge detection algorithm, which is non-contact and interference-free throughout the process; the axial tensile force can be obtained by installing a tensile force sensor at the connection position between the seed crystal chuck 220 and the lifting head 210. The lifting head 210 has a built-in water-cooled flange structure, so there is no problem of high temperature failure. The sensor setting is a conventional technical means, which will not be described in detail in this application; the length of the silicon core 500 can be obtained by subtracting the height of the lifting head 210 from the height of the molten zone; the molten zone temperature can be monitored by an infrared thermometer; the furnace temperature can be monitored by a thermocouple inserted into the furnace wall. The furnace temperature refers to the furnace atmosphere temperature at the midpoint height of the silicon furnace.

[0034] The second parameter group consists of independently adjustable control parameters, specifically including the heating temperature of the seed crystal chuck 220, the heating power of the corresponding silicon core 500 melting zone, and the hydrogen doping amount of the corresponding silicon core 500 melting zone. The above three parameters are configured independently for each silicon core 500, and the adjustment process does not interfere with each other. The growth rate of the silicon core 500 is controlled from three dimensions: initial crystallization conditions, melting zone temperature, and melting zone interface characteristics. This covers the adjustment dimensions that affect the growth rate of the silicon core 500, ensuring the effectiveness and flexibility of the adjustment.

[0035] Furthermore, this application further explains the function of the first function model, which aims to establish a mapping relationship between the first parameter set and the actual growth rate of silicon core 500; such as Figure 6 As shown, it includes: T21: Establishing the bending deflection of silicon core 500. 500mm silicon core length ,diameter Axial tension Melting zone temperature and furnace temperature Regarding the actual growth rate of silicon 500 The first function model; T22: Bending deflection based on collected data from silicon core 500 500mm silicon core length ,diameter Axial tension Melting zone temperature and furnace temperature And the first function model, to determine the actual growth rate of silicon core 500. .

[0036] It should be noted that the actual growth rate of the solid-liquid interface of the silicon core 500 is located in the high-temperature melting zone of 1412 degrees Celsius, which cannot be directly measured by installing sensors. This has long been an unmeasurable physical quantity in the industry. The first function model is constructed based on the mechanical properties of the slender rod of the silicon core 500 and the crystal growth kinetics. It can inversely deduce the actual growth rate of the silicon core 500 through measurable state parameters such as deformation, force, and temperature, realizing soft measurement of unmeasurable physical quantities. This breaks through the industry bottleneck that the growth rate cannot be directly measured in the high-temperature melting zone, and improves the perception accuracy of the growth rate from manual qualitative judgment to quantitative accuracy, providing a reliable basis for subsequent precise adjustment.

[0037] Specifically, the first function model is:

[0038] in, The mechanical lifting rate of the lifting head 210; The coefficient representing the influence of bending stress on the growth rate; The elastic modulus of silicon core 500; The moment of inertia of the cross section of silicon core 500; This is the coefficient representing the influence of axial stress on the growth rate. The axial tensile force of silicon core 500; This refers to the cross-sectional area of ​​a 500mm silicon core. This is the coefficient representing the influence of melting zone temperature on growth rate; This is the melting point of silicon.

[0039] Based on the aforementioned first function model, the actual growth rate of the solid-liquid interface of silicon core 500 is quantitatively calculated using measurable state parameters. The formula consists of the superposition of four terms with clear physical meanings; among them, the first term serves as the baseline term. , representing the mechanical pulling speed set by the lifting head 210, is a unified reference benchmark for the growth of all silicon cores 500. When there is no deviation, the actual growth rate is equal to the pulling speed. The second term is the bending stress-driven term, corresponding to the term in the formula. The physical meaning of this is the effect of the axial compressive stress generated by the 500 bending of the silicon core on the growth rate. This is the formula for calculating the bending stress of a double-constrained compression member in mechanics of materials. This is the coupling coefficient between bending stress and growth rate, a constant specific to silicon. When silicon core 500 grows too quickly, it will bend under pressure. The greater the bending deflection, the greater the compressive stress, and the faster the growth rate. This term accurately reflects the correspondence between bending deformation and growth rate. The third term is the axial stress-driven term, corresponding to the term in the formula. Its physical meaning is the effect of the axial tensile and compressive stress of the silicon core on the growth rate; The axial stress of silicon core 500 This is the coupling coefficient between axial stress and growth rate, a constant specific to silicon materials. When silicon core 500 grows too slowly, it will be under tension. Tensile stress will inhibit crystal nucleation and slow down the growth rate. When under pressure, it will accelerate the growth rate. This term accurately reflects the correspondence between axial force and growth rate. The fourth term is the melting zone temperature driving term, corresponding to the formula in... Its physical meaning is the effect of the superheat of the molten zone on the growth rate; among which The superheat of the molten zone, This is the coupling coefficient between the melting zone temperature and the growth rate, and is a constant specific to silicon materials. The higher the melting zone temperature, the greater the superheat, the smaller the supercooling during crystallization, and the slower the growth rate. This term accurately reflects the correspondence between the thermal state of the melting zone and the growth rate.

[0040] Furthermore, this application further explains the function of the second function model. The role of the second function model is to establish a mapping relationship between the second parameter set and the growth rate difference, thereby achieving quantitative prediction of the influence of the adjustment parameters on the rate difference; such as Figure 7 As shown, it includes: T41: Establish seed crystal chuck temperature 220℃ Melting zone heating power and the amount of hydrogen doping in the melting zone Regarding the rate difference The second function model; T42: Target-based rate difference The second function model was used to determine the 220°C temperature of the seed crystal chuck. Melting zone heating power and the amount of hydrogen doping in the melting zone .

[0041] The second function model is constructed based on the physical mechanism of each adjustment parameter. It can quantitatively predict the impact of changes in seed crystal chuck 220 temperature, melting zone heating power, and hydrogen doping on the growth rate difference, solving the problem that traditional empirical adjustment cannot predict the adjustment effect. This model provides a quantitative prediction basis for solving the optimal adjustment parameters, avoiding problems such as melting zone fluctuations and silicon core 500 defects caused by blind adjustment, and greatly improving the accuracy and response speed of adjustment.

[0042] Specifically, the second function model is as follows:

[0043]

[0044] in, For constant terms; The coefficient for the first term of heating power; The coefficient of the quadratic term of the heating power; The heater has a power rating of 310. The coefficient of the first term for hydrogen doping; The cross-term coefficient for hydrogen doping and undercooling; The amount of hydrogen component added to the cooling gas; This is the coefficient of the coupling term between the temperature and length of the clamp.

[0045] Based on the above formula, the effect of changes in regulation parameters on the growth rate difference can be quantitatively predicted. The formula consists of four terms with clear physical meanings, each of which corresponds to the mechanism of action of a regulation parameter. The first term is a constant term. This represents the inherent deviation of the system caused by equipment, raw materials, and processes. It is obtained through pre-experiment calibration and is used to eliminate fixed errors in the system.

[0046] The second term is the heating power term, corresponding to the formula in... Its physical meaning is the effect of the heating power of the molten zone on the difference in growth rate; among which This is the coefficient for the first term of heating power. A negative value indicates that increasing the heating power will raise the temperature of the melting zone and slow down the growth rate. This is the coefficient of the quadratic term of heating power. It is a positive value, which means that when the power is too high, a heat saturation effect will occur. If the power continues to increase, the effect on the growth rate will weaken. This term accurately reflects the regulation law of heating power. The third term is the hydrogen doping coupling term, corresponding to the formula in... Its physical meaning is the effect of hydrogen doping in the molten zone on the difference in growth rate. Among them... The first-order coefficient of hydrogen doping is positive, which means that increasing the hydrogen doping will increase the surface tension of molten silicon, accelerate heat dissipation in the molten zone, and increase the growth rate. The coefficient of the cross term between hydrogen doping and undercooling represents the strong correlation between the regulating effect of hydrogen and the undercooling of the molten zone. The greater the undercooling, the more significant the regulating effect of hydrogen. This term accurately reflects the regulating law of hydrogen doping.

[0047] The fourth term is the clamp temperature-length coupling term, corresponding to the formula in... Its physical meaning is the influence of the seed crystal chuck temperature of 220°C on the growth rate difference, while also considering the thermal conductivity attenuation effect of the 500mm silicon core length; among which The coupling coefficient is negative, indicating that an increase in chuck temperature reduces the 500-degree axial temperature gradient of the silicon core, thus slowing down the growth rate; the temperature difference divided by the 500-degree free length of the silicon core. This reflects the distance attenuation law of heat conduction along the silicon core 500 axis. The longer the silicon core 500, the weaker the temperature regulation effect of the chuck. This item accurately reflects the temperature regulation law of the chuck.

[0048] Based on the second function model, the optimal parameters can be derived by back-calculating the growth rate difference obtained from the first function model. Specifically, adjusting the second parameter set to ensure the rate difference is within a threshold includes: establishing a constrained optimization objective function and solving for the optimal parameters that minimize the rate difference, such as the seed crystal chuck temperature 220°C. Melting zone heating power and the amount of hydrogen doping in the melting zone ; The objective function to be optimized is .

[0049] A constrained optimization objective function is constructed based on the second function model. The optimization objective is to minimize the absolute value of the growth rate difference, while setting reasonable constraint ranges for each adjustment parameter to ensure the safety and stability of the adjustment process. Specifically, the optimization objective function minimizes the absolute value of the growth rate difference while satisfying constraints such as heating power between 0 and 5000 watts, hydrogen doping between 0 and 0.5%, and seed crystal chuck 220 temperature between 25 and 600 degrees Celsius.

[0050] By solving the above objective function using the least squares method or intelligent optimization algorithm, the optimal combination of seed crystal chuck temperature 220°C, optimal melting zone heating power, and optimal melting zone hydrogen doping can be obtained under the current state, making the difference in silicon core growth rate closest to 0. This replaces the traditional step-by-step empirical adjustment, achieving a one-time accurate solution for the optimal adjustment parameters, improving the adjustment response speed and significantly enhancing the adjustment accuracy, while avoiding melting zone fluctuations caused by repeated adjustments.

[0051] It should be noted that the silicon core 500 in this application has a large aspect ratio, and the Bi of the silicon core 500 is generally less than 0.1. The Bi of the silicon core 500 is the core criterion for judging the heat dissipation mode in the field of heat conduction. When the Bi of the silicon core 500 is less than 0.1, the axial heat conduction inside the silicon core 500 is absolutely dominant, and the influence of radial surface heat dissipation can be ignored. Therefore, this application ensures the effectiveness and stability of the adjustment by adding a mechanism for adjusting the axial temperature gradient through the seed crystal chuck 220.

[0052] This application also provides a growth control system for a silicon core furnace, including a data acquisition module, a calculation module, and a feedback module. The data acquisition module is used to acquire a first set of parameters for the silicon core 500. The calculation module is used to calculate the actual growth rate of the silicon core 500 based on the first set of parameters, and to calculate the rate difference based on the actual growth rate of the silicon core 500 and the mechanical lifting rate of the lifting head 210. The feedback module is used to adjust a second set of parameters so that the rate difference is within a threshold value.

[0053] The acquisition module is responsible for collecting all data from the first parameter group in real time, providing reliable status input to the calculation module. The feedback module is independently configured for each silicon core 500 and is responsible for executing the adjustment commands issued by the calculation module to independently adjust the second parameter group of each silicon core 500. The calculation module has built-in first function model, second function model and optimization solver, and is responsible for the entire process of data operation, actual growth rate calculation, rate difference calculation, optimal parameter solution and adjustment command issuance, realizing closed-loop automatic control. It realizes the fully automated execution of the control method without human intervention, greatly reduces the dependence on the experience of operators, significantly improves production stability and consistency, and provides a complete system architecture for the intelligent upgrade of silicon core furnaces.

[0054] This application also provides a silicon core furnace, such as Figure 1 , 2As shown in Figure 3, the silicon core furnace growth method described above is performed. The silicon core furnace includes a furnace body 100, a lifting assembly 200, a heating assembly 300, and a gas path assembly 400. The furnace body 100 provides a sealed and insulated space for the growth of the silicon core 500, isolates it from external environmental interference, and maintains a stable atmosphere and temperature field inside the furnace. The lifting assembly 200 is located on the top of the furnace body 100 and includes a liftable lifting head 210. Each silicon core 500 is independently equipped with a seed crystal chuck 220 on the lifting head 210. All seed crystal chucks 220 rise and fall synchronously with the lifting head 210 to ensure uniform mechanical lifting speed of multiple silicon cores 500. The lifting head 210 is driven to rise and fall vertically by a linear structure located on the top of the furnace body 100. For example, a linear motor or a lead screw module can be used. Each seed crystal chuck 220 integrates an independently temperature-controlled heating element, which can independently adjust the temperature of the corresponding seed crystal 230, reduce the temperature difference between the seed crystal 230 and the molten zone from the initial stage of pulling, reduce thermal shock, and can also serve as a fine-tuning actuator for the growth rate.

[0055] Heating components 300 are installed inside the furnace body 100, with independent heaters 310 for each silicon core 500. This allows for precise adjustment of the local temperature of the melting zone of a single silicon core 500, replacing the traditional one-size-fits-all heating mode of the main coil, and enabling medium to large-scale adjustment of the growth rate of a single silicon core 500. Gas path components 400 are introduced into the furnace body 100, with coaxial cooling gas pipes 410 independently installed for each silicon core 500. These pipes are connected to an external gas source for gas supply, and their outlets face the crystal growth interface of the corresponding silicon core 500. Each cooling gas pipe 410 is connected to an independently flow-controlled hydrogen branch pipe, allowing for independent supply of hydrogen-doped cooling gas to the crystal growth interface of the corresponding silicon core 500. This precisely adjusts the heat dissipation rate and molten silicon surface tension of the crystal growth interface of a single silicon core 500, achieving rapid and fine adjustment of the growth rate. Of course, it also includes a feeding mechanism located at the bottom of the furnace body 100 for upward feeding, which is used to maintain the top of the raw material rod 600 so that the top of the raw material rod 600 is within the heating range, and the top of the raw material rod 600 is the melting zone; the silicon core furnace also includes other conventional structures, which will not be described in detail in this embodiment.

[0056] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0057] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for controlling the growth of a silicon core furnace, characterized in that, Suitable for silicon core furnaces, the silicon core furnace having a seed crystal chuck (220) with a heating element disposed therein; the growth control method of the silicon core furnace includes: This causes the lifting head (210) to descend while carrying the seed crystal (230); The heating element heats the seed crystal chuck (220) and the seed crystal (230); The temperature difference between the seed crystal (230) and the melting zone is less than 400-800℃.

2. The growth control method for a silicon core furnace according to claim 1, characterized in that, Collect the first set of parameters for the silicon core (500); The actual growth rate of the silicon core (500) was calculated based on the first set of parameters; The rate difference is calculated based on the actual growth rate of the silicon core (500) and the mechanical pulling rate of the lifting head (210). Adjust the second parameter group so that the rate difference is within the threshold.

3. The growth control method for a silicon core furnace according to claim 2, characterized in that, The first parameter set includes: the bending deflection of the silicon core (500). Silicon core (500) length ,diameter Axial tension Melting zone temperature and furnace temperature ; The second parameter group includes: seed crystal chuck (220) temperature. Melting zone heating power and the amount of hydrogen doping in the melting zone .

4. The growth control method for a silicon core furnace according to claim 3, characterized in that, The calculation of the actual growth rate of the silicon core (500) based on the first parameter set includes: Establish the bending deflection of the silicon core (500). Silicon core (500) length ,diameter Axial tension Melting zone temperature and furnace temperature Regarding the actual growth rate of silicon core (500) The first function model; Based on the collected bending deflection of silicon core (500) Silicon core (500) length ,diameter Axial tension Melting zone temperature and furnace temperature And the first function model, to determine the actual growth rate of silicon core (500). .

5. The growth control method for a silicon core furnace according to claim 4, characterized in that, The first function model is: in, The mechanical lifting rate of the lifting head (210); The coefficient representing the influence of bending stress on the growth rate; The elastic modulus of the silicon core (500); Let be the moment of inertia of the cross section of the silicon core (500); This is the coefficient representing the influence of axial stress on the growth rate. The axial tensile force of the silicon core (500); This represents the cross-sectional area of ​​the silicon core (500). This is the coefficient representing the influence of melting zone temperature on growth rate; This is the melting point of silicon.

6. The growth control method for a silicon core furnace according to claim 3, characterized in that, The adjustment of the second parameter group, such that the rate difference is within the threshold, includes: Establish the seed crystal chuck (220) temperature Melting zone heating power and the amount of hydrogen doping in the melting zone Regarding the rate difference The second function model; Rate difference based on target The second function model is used to determine the temperature of the seed crystal chuck (220). Melting zone heating power and the amount of hydrogen doping in the melting zone .

7. The growth control method for a silicon core furnace according to claim 6, characterized in that, The second function model is: in, For constant terms; The coefficient for the first term of heating power; The coefficient of the quadratic term of the heating power; For the power of heater (310); The coefficient of the first term for hydrogen doping; The cross-term coefficient for hydrogen doping and undercooling; The amount of hydrogen component added to the cooling gas; This is the coefficient of the coupling term between the temperature and length of the clamp.

8. The growth control method for a silicon core furnace according to claim 7, wherein adjusting the second parameter group to make the rate difference within a threshold includes: Establish a constrained optimization objective function and solve for the optimal parameter that minimizes the rate difference: seed crystal chuck (220) temperature. Melting zone heating power and the amount of hydrogen doping in the melting zone ; The objective function to be optimized is .

9. A growth control system for a silicon core furnace as described in any one of claims 2-8, characterized in that, include: The acquisition module is used to acquire the first set of parameters of the silicon core (500); The calculation module is used to calculate the actual growth rate of the silicon core (500) based on the first parameter set, and to calculate the rate difference based on the actual growth rate of the silicon core (500) and the mechanical lifting rate of the lifting head (210). as well as The feedback module is used to adjust the second parameter group so that the rate difference is within the threshold.

10. A silicon core furnace, characterized in that, The silicon core furnace growth method according to any one of claims 1-8, wherein the silicon core furnace comprises: Furnace body (100); The lifting assembly (200) includes a lifting head (210), on which a seed crystal chuck (220) is independently provided for each silicon core (500). The seed crystal chuck (220) is used to hold the seed crystal (230) to simultaneously pull multiple silicon cores (500), and each seed crystal chuck (220) is provided with an independently temperature-controlled heating element for independently adjusting the temperature of the corresponding seed crystal (230). A heating assembly (300) is disposed within the furnace body (100) and includes a heater (310) independently configured and controlled for each silicon core (500) to independently adjust the local temperature of the melting zone of the corresponding silicon core (500); and Gas path assembly (400) is disposed inside furnace body (100) and includes coaxial cooling gas pipe (410) independently disposed for each silicon core (500). The outlet of the cooling gas pipe (410) faces the crystal growth interface of the corresponding silicon core (500). Each cooling gas pipe (410) is connected to a hydrogen branch pipe with independent flow control for independently supplying hydrogen doping to the crystal growth interface of the corresponding silicon core (500).

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