CN116065236A

CN116065236A - Crystal growth control method and device, electronic equipment and storage medium

Info

Publication number: CN116065236A
Application number: CN202111279573.9A
Authority: CN
Inventors: 张伟建; 郭力; 杨正华; 王正远
Original assignee: Longi Green Energy Technology Co Ltd
Current assignee: Longi Green Energy Technology Co Ltd
Priority date: 2021-10-29
Filing date: 2021-10-29
Publication date: 2023-05-05

Abstract

The application provides a crystal growth control method, a crystal growth control device, electronic equipment and a storage medium, and relates to the technical field of solar photovoltaics. In the seeding process, the temperature control can be performed by adjusting the rotation speed of the crucible by adopting a temperature proportional coefficient and a temperature differential coefficient, and the temperature control in the seeding process can be performed in a manner of adjusting the rotation speed of the crucible, so that the temperature of a thermal field can be controlled timely and stably under the adjustment of the temperature proportional coefficient and the temperature differential coefficient; the diameter difference between the real-time diameter and the target diameter can be determined, the aperture width change rate in the width measurement period is determined, and the pulling speed of the single crystal is adjusted according to the diameter difference, the aperture width change rate, the diameter proportional coefficient, the diameter integral coefficient and the diameter differential coefficient so as to control the diameter.

Description

Crystal growth control method and device, electronic equipment and storage medium

Technical Field

The present disclosure relates to the field of solar photovoltaic technologies, and in particular, to a method and an apparatus for controlling crystal growth, an electronic device, and a storage medium.

Background

In the preparation of monocrystalline silicon, a Czochralski process is usually adopted, and the process comprises the steps of placing a high-purity silicon material into a crucible, heating and melting in a single crystal furnace, immersing a seed crystal into a silicon melt, controlling parameters such as power supply, pulling speed, rotating speed and the like, and carrying out operation steps such as seeding, necking, isodiametric growth, ending and the like to prepare the monocrystalline silicon.

The seed crystal is immersed into the silicon melt in the seeding stage, then the seed crystal is pulled upwards and rotated to lead out the crystal, and the diameter and temperature control fluctuation of the seed crystal in the seeding stage are large, so that the stability of the seed crystal is poor, the dislocation elimination degree of monocrystalline silicon in the seeding stage is low, and the risk of line breakage in the subsequent process is high.

At present, longer seed crystals are usually adopted in the seeding stage to solve the dislocation problem, but the longer seed crystals cause material waste, the risk of seeding failure is promoted, the problem of seed crystal bearing cannot be solved, and breakage easily occurs in the crystal pulling process.

Disclosure of Invention

The application provides a crystal growth control method, a crystal growth control device, electronic equipment and a storage medium, and aims to improve seed crystal stability, reduce the risk of seed crystal breakage in a single crystal preparation process and improve the product yield.

In a first aspect, an embodiment of the present application provides a method for controlling crystal growth, where the method includes:

in the seeding process, temperature control is performed by adopting a temperature proportional coefficient and a temperature differential coefficient, and/or diameter control is performed by adopting a diameter proportional coefficient, a diameter integral coefficient and a diameter differential coefficient; wherein,,

the temperature control by adopting the temperature proportional coefficient and the temperature differential coefficient comprises the following steps:

collecting the real-time brightness of the liquid level;

determining the brightness difference between the real-time brightness and the target brightness;

determining a brightness change rate in a brightness measurement period;

adjusting the rotation speed of the crucible according to the brightness difference, the brightness change rate, the temperature proportional coefficient and the temperature differential coefficient so as to control the temperature;

the diameter control is carried out by adopting a diameter proportional coefficient, a diameter integral coefficient and a diameter differential coefficient, and the method comprises the following steps:

acquiring a real-time diameter and an aperture width;

determining a diameter difference between the real-time diameter and the target diameter;

determining a rate of change of aperture width in a width measurement period;

and adjusting the pulling speed of the single crystal according to the diameter difference, the aperture width change rate, the diameter proportional coefficient, the diameter integral coefficient and the diameter differential coefficient so as to control the diameter.

Optionally, the adjusting the crucible rotation speed according to the brightness difference, the brightness change rate, the temperature proportionality coefficient and the temperature differential coefficient to perform temperature control includes:

determining a first rotating speed adjustment amount according to the brightness difference and the temperature proportional coefficient;

determining a second adjustment amount of the rotating speed according to the brightness change rate and the temperature differential coefficient;

and adjusting the rotation speed of the crucible according to the first rotation speed adjustment amount and the second rotation speed adjustment amount so as to control the temperature.

Optionally, the adjusting the pulling speed of the single crystal according to the diameter difference, the aperture width change rate, the diameter proportionality coefficient, the diameter integral coefficient and the diameter differential coefficient to perform diameter control includes:

determining a first pull speed adjustment amount according to the diameter difference, the diameter proportional coefficient and the diameter integral coefficient;

determining a second pull speed adjustment amount according to the aperture width change rate and the diameter differential coefficient;

and adjusting the pulling speed of the single crystal according to the first pulling speed adjusting amount and the second pulling speed adjusting amount so as to control the diameter.

Optionally, the collecting the real-time brightness of the liquid level includes:

Collecting the measurement brightness of at least two temperature measuring points distributed on the liquid level instead of the liquid level;

fitting the measured brightness to determine the real-time brightness of the liquid level.

Optionally, the adjusting the rotation speed of the crucible according to the first rotation speed adjustment amount and the second rotation speed adjustment amount includes:

determining the total rotating speed adjustment amount of the crucible according to the first rotating speed adjustment amount and the second rotating speed adjustment amount;

determining a single adjustment amount and a rotation speed adjustment period for adjusting the rotation speed of the crucible;

determining the adjustment times and adjustment time length according to the single adjustment amount, the rotation speed adjustment period and the total crucible rotation speed adjustment amount;

and adjusting the rotating speed of the crucible according to the adjusting duration and the adjusting times.

Optionally, the acquiring the real-time diameter and the aperture width includes:

acquiring diameter pixels and aperture pixels in the seeding process;

determining the real-time diameter according to a pixel calibration relation and the diameter pixels, wherein the pixel calibration relation is used for representing the corresponding relation between the number of pixels and the actual length;

and determining the aperture width according to the pixel calibration relation and the aperture pixel.

Optionally, the determining the first pull rate adjustment according to the diameter difference, the diameter proportional coefficient, and the diameter integral coefficient includes:

Determining a first product of the diameter difference and the diameter scaling factor;

determining a second product of the diameter difference and the diameter integration coefficient and a pull rate integration period;

and determining the first pull speed adjustment amount according to the first product and the second product.

In a second aspect, an embodiment of the present application provides a control device for crystal growth, including:

the temperature control module is used for performing temperature control by adopting a temperature proportional coefficient and a temperature differential coefficient in the seeding process; and/or the number of the groups of groups,

the diameter control module is used for performing diameter control by adopting a diameter proportional coefficient, a diameter integral coefficient and a diameter differential coefficient in the seeding process; wherein,,

the temperature control module includes:

the first acquisition submodule is used for acquiring the real-time brightness of the liquid level;

the brightness difference determining sub-module is used for determining the brightness difference between the real-time brightness and the target brightness;

a luminance change rate determination submodule for determining a luminance change rate in a luminance measurement period;

the rotating speed adjusting submodule is used for adjusting the rotating speed of the crucible according to the brightness difference, the brightness change rate, the temperature proportional coefficient and the temperature differential coefficient so as to control the temperature;

The diameter control module includes:

the second acquisition submodule is used for acquiring the real-time diameter and the aperture width;

a diameter difference determination submodule for determining a diameter difference between the real-time diameter and the target diameter;

a width change rate determination submodule for determining a diaphragm width change rate in a width measurement period;

and the pulling speed adjusting sub-module is used for adjusting the pulling speed of the single crystal according to the diameter difference, the aperture width change rate, the diameter proportional coefficient, the diameter integral coefficient and the diameter differential coefficient so as to control the diameter.

Optionally, the rotation speed adjustment sub-module includes:

a rotation speed first adjustment amount determining unit, configured to determine a rotation speed first adjustment amount according to the brightness difference and the temperature scaling factor;

a rotation speed second adjustment amount determining unit configured to determine a rotation speed second adjustment amount according to the luminance change rate and the temperature differential coefficient;

and the crucible rotating speed adjusting unit is used for adjusting the rotating speed of the crucible according to the rotating speed first adjusting amount and the rotating speed second adjusting amount so as to control the temperature.

The pull rate adjustment sub-module comprises:

a pull speed first adjustment amount determining unit, configured to determine a pull speed first adjustment amount according to the diameter difference, the diameter proportional coefficient, and the diameter integral coefficient;

A pull-speed second adjustment amount determining unit configured to determine a pull-speed second adjustment amount according to the aperture width change rate and the diameter differential coefficient;

and the single crystal pulling speed adjusting unit is used for adjusting the single crystal pulling speed according to the first pulling speed adjusting amount and the second pulling speed adjusting amount so as to control the diameter.

Optionally, the first collecting sub-module includes:

the measuring brightness acquisition unit is used for acquiring the measuring brightness of at least two temperature measuring points distributed on the liquid level instead of the liquid level;

and the real-time brightness determining unit is used for fitting the measured brightness and determining the real-time brightness of the liquid level.

Optionally, the crucible rotation speed adjusting unit includes:

the first adjustment total amount determining subunit is used for determining the crucible rotation speed adjustment total amount according to the rotation speed first adjustment amount and the rotation speed second adjustment amount;

the rotating speed adjusting parameter determining subunit is used for determining a single adjusting quantity and a rotating speed adjusting period for adjusting the rotating speed of the crucible;

the rotating speed adjusting mode determining subunit is used for determining the adjusting times and the adjusting time length according to the single adjusting amount, the rotating speed adjusting period and the crucible rotating speed adjusting total amount;

And the crucible rotating speed adjusting subunit is used for adjusting the crucible rotating speed according to the adjusting duration and the adjusting times.

Optionally, the second acquisition sub-module includes:

the pixel acquisition unit is used for acquiring diameter pixels and aperture pixels in the seeding process;

the real-time diameter determining unit is used for determining the real-time diameter according to a pixel calibration relation and the diameter pixels, wherein the pixel calibration relation is used for representing the corresponding relation between the number of pixels and the actual length;

and the aperture width determining unit is used for determining the aperture width according to the pixel calibration relation and the aperture pixels.

Optionally, the pull-speed first adjustment amount determining unit includes:

a first product determination subunit configured to determine a first product of the diameter difference and the diameter scaling factor;

a second product determination subunit configured to determine a second product of the diameter difference and the diameter integration coefficient, and a pull-speed integration period;

and the pull speed first adjustment amount determining subunit is used for determining the pull speed first adjustment amount according to the first product and the second product.

In a third aspect, an embodiment of the present application provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, where the processor, the communication interface, and the memory complete communication with each other through the communication bus;

A memory for storing a computer program;

a processor for implementing the steps of the method for controlling crystal growth as described in the first aspect when executing a program stored on a memory.

In a fourth aspect, embodiments of the present application provide a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the crystal growth control method according to the first aspect.

In the seeding process, a temperature proportional coefficient and a temperature differential coefficient can be adopted to perform temperature control, the real-time brightness of a liquid level is collected, the brightness difference between the liquid level and the target brightness is determined, the brightness change rate in a brightness measurement period is determined, the crucible rotating speed is adjusted according to the brightness difference, the brightness change rate, the temperature proportional coefficient and the temperature differential coefficient to perform temperature control, the temperature control in the seeding process is performed by adopting a mode of adjusting the crucible rotating speed, and the temperature of a thermal field can be timely and stably controlled under the adjustment of the temperature proportional coefficient and the temperature differential coefficient; the diameter control can be carried out by adopting a diameter proportional coefficient, a diameter integral coefficient and a diameter differential coefficient, the real-time diameter and the aperture width are obtained specifically, the diameter difference between the real-time diameter and the target diameter is determined, the aperture width change rate in the width measurement period is determined, the pulling speed of the single crystal is regulated according to the diameter difference, the aperture width change rate, the diameter proportional coefficient, the diameter integral coefficient and the diameter differential coefficient, so that the diameter control is carried out.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments of the present application will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 shows a step flowchart of a method for controlling crystal growth according to an embodiment of the present application;

FIG. 2 is a flow chart illustrating steps of another method for controlling crystal growth according to an embodiment of the present application;

FIG. 3 is a block diagram showing a crystal growth control apparatus according to an embodiment of the present application;

fig. 4 shows a schematic structural diagram of a crystal growth control apparatus according to an embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

Referring to fig. 1, fig. 1 shows a flowchart of steps of a method for controlling crystal growth according to an embodiment of the present application, and as shown in fig. 1, the method may include:

in step 101, in the seeding process, temperature control is performed by using a temperature proportional coefficient and a temperature differential coefficient, and/or diameter control is performed by using a diameter proportional coefficient, a diameter integral coefficient and a diameter differential coefficient.

In the embodiment of the application, the temperature refers to the temperature of the liquid level of the silicon melt, the diameter refers to the diameter of the crystal led out in the crystal seeding process, and at least one of the temperature and the diameter is controlled in the crystal seeding process, so that the diameter of the crystal can be ensured to grow in a preset range. PID regulation is a method for regulating by adopting deviation proportion (P), integral (I) and derivative (D) in the process of executing the process steps, can accurately and stably regulate parameters, can control the temperature by adopting a temperature proportion coefficient and a temperature derivative coefficient to PD, can control thermal field change more stably, can control the diameter by adopting a diameter proportion coefficient, a diameter integral coefficient and a diameter derivative coefficient to PID, and can regulate diameter fluctuation stably and accurately.

Optionally, in step 101, the temperature control using a temperature proportional coefficient and a temperature differential coefficient includes:

And 102, collecting the real-time brightness of the liquid level.

In the embodiment of the application, the liquid level temperature of the silicon melt has a great influence on crystal growth, optionally, in order to avoid pollution problems possibly caused by contact with the liquid level temperature measurement, and based on the relationship between the brightness and the temperature of the surface of the silicon melt, the real-time brightness of the liquid level can be collected, and the real-time temperature of the liquid level can be reflected by the real-time brightness.

Step 103, determining the brightness difference between the real-time brightness and the target brightness.

In this embodiment of the present application, the target temperature may be a temperature of a silicon melt liquid surface capable of ensuring that the thermal field meets a crystal growth requirement, and under the target temperature, a crystal diameter fluctuation amount caused by temperature fluctuation may be reduced, so that by controlling the temperature to reduce the diameter deviation, optionally, the target temperature may be converted into a target brightness of the silicon melt liquid surface through a relationship between the temperature and the brightness, and a brightness difference between the real-time brightness and the target brightness is determined to determine an adjustment range of the brightness.

Step 104, determining the brightness change rate in the brightness measurement period.

In this embodiment of the present application, the luminance measurement period may be a period of time before the measurement time of the real-time luminance, the luminance change rate is a change rate of the liquid level luminance of the silicon melt in the luminance measurement period, and the luminance change amounts between the start luminance and the end luminance of the start time and the end luminance of the end time and the duration of the luminance measurement period may be respectively determined in the luminance measurement period, where the end time of the luminance measurement period may be the measurement time of the real-time luminance, or may be before the measurement time of the real-time luminance.

And step 105, adjusting the rotation speed of the crucible according to the brightness difference, the brightness change rate, the temperature proportional coefficient and the temperature differential coefficient so as to control the temperature.

In the embodiment of the application, the rotation speed of the crucible is an important factor influencing the thermal field in the process of preparing the single crystal by the Czochralski method, and the thermal field can be influenced by adjusting the rotation speed of the crucible, so that the temperature adjustment is performed. The temperature regulation range of the demand can be determined according to the brightness difference, the temperature change condition in the thermal field can be determined according to the brightness change rate, at the moment, parameters such as the brightness difference, the brightness change rate and the like can be regulated by adopting a temperature proportion coefficient and a temperature differential coefficient, so that the regulating quantity of the rotating speed of the crucible is determined, and the rotating speed of the crucible is regulated, wherein the temperature proportion coefficient and the temperature differential coefficient can be obtained through preset, can also be obtained through correction of preset parameters through experimental tests, can be used for controlling the temperature of the rotating speed of the crucible, can be used for regulating the temperature of the thermal field more rapidly and stably in time, and further can be used for reducing the fluctuation quantity of the diameter through controlling the temperature, so that the quality of crystals is improved.

Optionally, in step 101, the diameter control using a diameter proportional coefficient, a diameter integral coefficient, and a diameter differential coefficient includes:

step 106, acquiring the real-time diameter and the aperture width.

In this embodiment, the aperture is a halo formed at the junction of the liquid surface of the silicon melt and the solid crystal, and is formed by reflection of the meniscus at the solid-liquid junction on the crucible wall light, so that the real-time diameter may be the inner diameter of the halo, and the aperture width may be the width of the halo, that is, the difference between the outer diameter and the inner diameter of the halo, optionally, the brightness distribution of the liquid surface may be collected, and edge capturing is performed according to the brightness distribution, thereby determining the real-time diameter of the crystal, and the aperture width.

Step 107, determining a diameter difference between the real-time diameter and the target diameter.

In this embodiment of the present application, the target diameter may be a diameter that ensures that the fluctuation amount of the crystal diameter is within an acceptable range in the crystal preparation process, and when the deviation between the real-time diameter and the target diameter reaches a certain degree, the real-time diameter may be controlled to approach or reach the target diameter, so that after the real-time diameter is obtained, the diameter difference between the real-time diameter and the target diameter may be determined.

Step 108, determining the aperture width change rate in the width measurement period.

In this embodiment of the present application, the width measurement period may be a period before a measurement time of a real-time diameter, where the aperture width change rate is a change rate of a bright ring width on a liquid level in the width measurement period, an aperture width change amount between a start aperture width of a start time and an end aperture width of an end time and a duration of the width measurement period may be calculated respectively in the width measurement period, where the end time of the width measurement period may be a measurement time of the real-time diameter, or before the measurement time of the real-time diameter, optionally, the aperture width change rate may be processed by adopting a weight adaptive denoising manner, so as to improve data accuracy.

And 109, adjusting the pulling speed of the single crystal according to the diameter difference, the aperture width change rate, the diameter proportional coefficient, the diameter integral coefficient and the diameter differential coefficient so as to control the diameter.

In the implementation of the present application, the fluctuation amount of the crystal diameter is an important factor affecting the crystal quality, the crystal diameter is related to the growth speed of the crystal, and the growth speed of the crystal is related to the pulling speed of the single crystal, so that the adjustment of the crystal diameter can be realized by adjusting the pulling speed of the single crystal. The diameter adjustment range required by the diameter difference can be determined, the diameter change condition can be determined according to the aperture width change rate, at the moment, parameters such as the diameter proportional coefficient, the diameter integral coefficient and the diameter differential coefficient can be adopted to adjust the diameter difference, the aperture width change rate and the like, so that the adjustment quantity of the pulling speed of the single crystal can be determined, and then the pulling speed of the single crystal can be adjusted, wherein the diameter proportional coefficient, the diameter differential coefficient and the diameter integral coefficient can be obtained through preset, also can be obtained through correction of preset parameters through experimental tests, the diameter control is carried out on the pulling speed of the single crystal under the adjustment of the coefficients, the real-time diameter can be accurately and stably adjusted to the target diameter, the fluctuation quantity of the diameter can be effectively reduced, the overshoot can be better eliminated, and the quality of the crystal can be improved.

In this embodiment, temperature control, diameter control, etc. may be performed selectively or simultaneously, and temperature control, diameter control, etc. may be performed simultaneously in the seeding process.

Referring to fig. 2, fig. 2 is a flowchart illustrating steps of another method for controlling crystal growth according to an embodiment of the present application, and referring to fig. 2, the method may include:

in step 201, in the seeding process, a temperature proportional coefficient and a temperature differential coefficient are used for temperature control, and/or a diameter proportional coefficient, a diameter integral coefficient and a diameter differential coefficient are used for diameter control.

In this embodiment, step 201 may correspond to the description of step 101, and is not repeated here.

The temperature control using the temperature proportional coefficient and the temperature differential coefficient in the step 201 includes:

step 202, collecting measurement brightness of at least two temperature measuring points distributed on the liquid level.

In this embodiment of the present application, at least two temperature measurement points may be determined on the liquid surface, where the temperature measurement points may be set at different positions on the liquid surface according to measurement requirements, and the number and positions of the temperature measurement points are not limited specifically. After the temperature measuring points are determined, the measured brightness of different temperature measuring points on the liquid surface can be acquired, and the measured brightness can reflect the temperature conditions of the temperature measuring points based on the relation between the temperature and the brightness, so that the temperature conditions of multiple points on the liquid surface are reflected. Alternatively, a CCD (Charge Coupled Device ) camera, CMOS (Compound metal Oxided Semiconductor, composite metal oxide semiconductor) camera, or the like may be used to obtain the measured brightness of the above-liquid-level temperature measurement point by the photoelectric conversion principle, which is not particularly limited in the embodiment of the present application.

And 203, fitting the measured brightness to determine the real-time brightness of the liquid level.

In this embodiment of the present application, the measured brightness of the temperature measuring point may be fitted, so that the obtained real-time brightness may accurately reflect the brightness condition of the measured area of the liquid level, where each measured brightness may be averaged, or the measured brightness may be averaged after the maximum value and the minimum value are removed, and the obtained average value is used as the real-time brightness of the liquid level.

Step 204, determining the brightness difference between the real-time brightness and the target brightness.

In this embodiment, step 204 may correspond to the description of step 103, and is not repeated here.

Step 205, determining a brightness change rate in a brightness measurement period.

In this embodiment, step 205 may correspond to the description of step 104, and is not repeated here.

And 206, determining a first rotating speed adjustment amount according to the brightness difference and the temperature proportionality coefficient.

In the embodiment of the application, the temperature proportionality coefficient is the proportionality coefficient P set when the PD control is adopted to perform proportionality control on the temperature, the temperature proportionality coefficient can be obtained through presetting, testing and correcting in a process of adjusting the real-time brightness to the target brightness, and the temperature control is realized through adjusting the rotating speed of the crucible, so that the diameter proportionality coefficient can also reflect the relation between the brightness difference and the rotating speed adjustment quantity of the crucible, and the first rotating speed adjustment quantity is obtained by adopting the gain of the brightness difference which is proportionally changed by adopting the temperature proportionality coefficient, thereby reducing the steady-state error of the system and improving the control precision.

And step 207, determining a second rotation speed adjustment amount according to the brightness change rate and the temperature differential coefficient.

In the embodiment of the application, the temperature differential coefficient is a differential coefficient D which is set when differential control is performed on temperature by PD control, the temperature differential coefficient can be obtained by presetting, testing and correcting in a process of adjusting real-time brightness to target brightness, the temperature differential coefficient can reflect the change trend of the rotating speed of the crucible, and the obtained rotating speed second adjustment quantity can predict the deviation of the rotating speed by differentiating the brightness change rate by adopting the temperature differential coefficient, so that the advanced correction effect is realized, overshoot is effectively reduced, and the stability of a system is ensured.

And step 208, adjusting the rotation speed of the crucible according to the first rotation speed adjustment amount and the second rotation speed adjustment amount so as to control the temperature.

According to the embodiment of the application, on the basis of the current crucible rotating speed, the crucible rotating speed is adjusted based on the first rotating speed adjusting amount and the second rotating speed adjusting amount, so that the adjusting amount of the crucible rotating speed can be in proportional reaction brightness difference, and prediction of crucible rotating speed deviation is performed, PD control on temperature is achieved, and control precision, steady-state performance and the like of a system are effectively guaranteed.

Optionally, the step 208 includes:

and S11, determining the total amount of crucible rotation speed adjustment according to the first rotation speed adjustment amount and the second rotation speed adjustment amount.

According to the crucible rotating speed adjusting method and device, the crucible rotating speed adjusting total amount can be determined according to the rotating speed first adjusting amount and the rotating speed second adjusting amount, and the crucible rotating speed can be adjusted stably and accurately based on the crucible rotating speed adjusting total amount, so that the liquid level temperature of the liquid level in the crucible after adjustment reaches the target temperature, and the crucible rotating speed adjusting total amount can be obtained by adding the rotating speed first adjusting amount and the rotating speed second adjusting amount.

And step S12, determining a single adjustment amount and a rotation speed adjustment period for adjusting the rotation speed of the crucible.

In this embodiment of the present application, according to various parameters such as actual control precision of the crucible, an expected rotation speed, and an adjustment total amount of the crucible, a single adjustment amount of the rotation speed of the crucible and a rotation speed adjustment period may be set, where the single adjustment amount refers to a numerical variation of the rotation speed of the crucible after each adjustment of the rotation speed of the crucible, and the rotation speed adjustment period refers to a duration of each adjustment of the rotation speed of the crucible, if the single adjustment amount is k, and the rotation speed adjustment period is T, then the variation of the rotation speed of the crucible in the T period in the single adjustment of the rotation speed of the crucible is k.

And S13, determining the adjustment times and the adjustment time length according to the single adjustment amount, the rotation speed adjustment period and the total crucible rotation speed adjustment amount.

In the embodiment of the application, the adjustment times for adjusting the rotation speed of the crucible can be determined according to the single adjustment amount and the total adjustment amount of the rotation speed of the crucible, and the corresponding number of rotation speed adjustment periods can be determined according to the adjustment times, so that the total adjustment time length is determined.

And S14, adjusting the rotating speed of the crucible according to the adjustment duration and the adjustment times.

According to the embodiment of the application, the crucible rotating speed can be adjusted according to the adjustment times on the basis of the current crucible rotating speed of the crucible, the single adjustment quantity is completed in the rotating speed adjustment period each time, and the adjustment of the crucible rotating speed is completed in the adjustment time length, so that PD control of the liquid level temperature in the crucible is realized.

The diameter control in step 201 using a diameter proportional coefficient, a diameter integral coefficient, and a diameter differential coefficient includes:

step 209, obtaining diameter pixels and aperture pixels in the seeding process.

In the embodiment of the application, the image of the liquid level in the seeding process can be obtained, the diameter pixel and the aperture pixel are determined according to the pixel distribution in the image, and the pixel value is the assigned value when the image is digitized, so that the average brightness information of the pixel can be reflected, the edge capturing can be performed according to the pixel value, or the pixel distribution can be determined by scanning by adopting a scanning line according to the pixel value, so that the aperture pixel and the diameter pixel are determined in the image. The aperture pixels may be pixels which are annularly arranged and have brightness reaching the aperture brightness according to the pixel value, and the diameter pixels may be pixels which are arranged in the aperture pixel ring, alternatively, a CCD camera, a CMOS camera, or the like may be used to obtain an image of the liquid surface in the seeding process, which is not particularly limited in the embodiment of the present application.

Step 210, determining the real-time diameter according to a pixel calibration relation and the diameter pixel, wherein the pixel calibration relation is used for representing the corresponding relation between the number of pixels and the actual length.

In this embodiment of the present application, the relationship between the number of pixels and the actual length may be represented by a pixel calibration relationship, for example, a relationship between the number of pixels corresponding to the inner diameter of a ring on an image and the length of the inner diameter of the ring, where the pixel calibration relationship may be obtained by measuring and calculating the number of pixels with a known length in the image, and the number of diameter pixels refers to the number of pixels distributed on the diameter of the ring in the aperture, and the length is determined based on the number of diameter pixels to be the length of the real-time diameter of the crystal in the seeding process.

Step 211, determining the aperture width according to the pixel calibration relation and the aperture pixel.

In this embodiment of the present application, the number of aperture pixels refers to the number of pixels distributed on the diameter between the inner ring and the outer ring of the aperture, and the length determined based on the number of aperture pixels is the aperture width of the aperture in the seeding process.

Step 212, determining the diameter difference between the real-time diameter and the target diameter.

In this embodiment, step 212 may correspond to the related description of step 107, and is not repeated here.

Step 213, determining the aperture width change rate in the width measurement period.

In this embodiment, step 213 may correspond to the related description of step 108, and is not repeated here.

Step 214, determining a first pull speed adjustment amount according to the diameter difference, the diameter proportional coefficient and the diameter integral coefficient.

In the embodiment of the application, the diameter proportionality coefficient is a proportionality coefficient P which is set when the diameter is proportionally controlled by PID control, and can be obtained by presetting, testing and correcting in a process of adjusting the implementation diameter to the target diameter, wherein the diameter proportionality coefficient proportionally changes the gain of the diameter difference; the diameter integral coefficient is an integral coefficient I which eliminates steady-state error setting when diameter control is carried out by PID control, the diameter integral coefficient is related with the accumulation of the change of the diameter difference in a time period, and the first pull speed adjustment quantity can be determined according to the diameter difference, the diameter proportion coefficient, the diameter integral coefficient and the like, and can effectively reduce the steady-state error of the system and improve the control precision and the response speed.

Optionally, the step 214 includes:

step S21, determining a first product of the diameter difference and the diameter proportionality coefficient.

In this embodiment of the present application, the first product is obtained by changing the diameter difference in proportion with a diameter scaling factor, so that the strength of the function of controlling the diameter can be adjusted to reduce the steady-state error of the system, where, because the diameter control is implemented by controlling the pulling rate of the single crystal, the relationship between the diameter difference and the pulling rate adjustment amount of the single crystal can also be reflected in the diameter scaling factor, and the first product may be the pulling rate adjustment amount of the single crystal determined by changing the diameter scaling factor in proportion with the diameter difference.

Step S22, determining a second product of the diameter difference, the diameter integral coefficient and the pull-speed integral period.

In this embodiment of the present application, the pull speed integration period may represent a period of accumulating the pull speed variation amount once, where the pull speed of each integration may be determined according to a trend of change of the pull speed in each integration period, for example, the pull speed integration period may represent integrating the pull speed a every T time, that is, the pull speed change a every T time, and on this basis, a diameter integral coefficient is adopted, so that a second product of the diameter difference, the diameter integral coefficient, and the pull speed integration period may be determined, where the second product may reflect an accumulated condition of the pull speed deviation.

And S23, determining the first pull speed adjustment amount according to the first product and the second product.

In this embodiment of the present application, the first adjustment amount of the pull speed may include a first product and a second product, so that the first adjustment amount of the pull speed may effectively reduce a steady-state error, and improve control accuracy of a system.

And step 215, determining a second pull-out speed adjustment amount according to the aperture width change rate and the diameter differential coefficient.

In the embodiment of the application, the diameter differential coefficient is a differential coefficient D which is set when the diameter is subjected to differential control by adopting PID control, the diameter differential coefficient can be obtained by presetting, testing and correcting in a process of adjusting the real-time diameter to the target diameter, the diameter differential coefficient can reflect the variation trend of the pulling speed deviation of the single crystal, and the brightness variation rate is differentiated by adopting the diameter differential coefficient, so that the pulling speed deviation can be predicted by obtaining the second adjustment quantity of the pulling speed, thereby realizing the advanced correction effect, effectively reducing overshoot and ensuring the stability of the system.

And step 216, adjusting the pulling speed of the single crystal according to the first pulling speed adjustment amount and the second pulling speed adjustment amount so as to control the diameter.

According to the embodiment of the application, on the basis of the current single crystal pulling speed, the single crystal pulling speed is adjusted based on the first pulling speed adjusting amount and the second pulling speed adjusting amount, so that the single crystal pulling speed adjusting amount can be used for proportionally reacting the diameter difference and predicting the pulling speed deviation, PID control on the diameter is realized, the control precision and steady-state performance of a system are effectively ensured, and overshoot is eliminated. Alternatively, referring to the foregoing steps S11 to S14, the total amount of pull rate adjustment for the pull rate of the single crystal may be determined according to the first adjustment amount of the pull rate and the second adjustment amount of the pull rate, and then the adjustment manner may be determined according to the preset single adjustment amount of the pull rate, the pull rate adjustment period, etc., so as to adjust the pull rate of the single crystal to control the diameter.

In the embodiment of the application, the upper limit, the lower limit and the like can be set for the single crystal pulling speed to limit the adjustment range of the single crystal pulling speed, and the safe pulling speed can be set so that when the crystal diameter is thin and the fracture risk exists, the crystal pulling speed is reduced to the safe pulling speed to avoid the fracture of the crystal.

In the embodiment of the application, after diameter control and temperature control are realized, the target diameter can be further reduced, for example, the set value of the target diameter can be 5.5-6.0 mm when the diameter control and the temperature control are performed, and after the diameter control is realized, the target diameter can be set to be 4.5-5 mm again, so that the crystal diameter in the seeding process is integrally narrowed, and meanwhile, the bearing capacity of the seed crystal can be maintained.

Fig. 3 shows a block diagram of a crystal growth control device 30 according to an embodiment of the present application, and as shown in fig. 3, the device may include:

the temperature control module 301 is configured to perform temperature control by using a temperature proportional coefficient and a temperature differential coefficient in the seeding process; and/or the number of the groups of groups,

the diameter control module 302 is configured to perform diameter control by using a diameter proportional coefficient, a diameter integral coefficient, and a diameter differential coefficient in the seeding process; wherein,,

the temperature control module 301 includes:

a first collecting submodule 3011, configured to collect real-time brightness of the liquid level;

a luminance difference determination submodule 3012 for determining a luminance difference between the real-time luminance and the target luminance;

a luminance change rate determination submodule 3013 for determining a luminance change rate in a luminance measurement period;

the rotating speed adjusting submodule 3014 is used for adjusting the rotating speed of the crucible according to the brightness difference, the brightness change rate, the temperature proportional coefficient and the temperature differential coefficient so as to control the temperature;

the diameter control module 302 includes:

a second acquisition submodule 3021 for acquiring the real-time diameter and the aperture width;

a diameter difference determination submodule 3022 for determining a diameter difference between the real-time diameter and the target diameter;

A width change rate determination submodule 3023 for determining a diaphragm width change rate in the width measurement period;

and a pulling speed adjusting sub-module 3024 for adjusting the pulling speed of the single crystal according to the diameter difference, the aperture width change rate, the diameter proportionality coefficient, the diameter integral coefficient and the diameter differential coefficient so as to control the diameter.

Optionally, the rotation speed adjustment submodule 3014 includes:

Optionally, the pull-speed adjustment sub-module 3024 includes:

Optionally, the first collecting submodule 3011 includes:

Optionally, the crucible rotation speed adjusting unit includes:

Optionally, the second collecting submodule 3021 includes:

Optionally, the pull-speed first adjustment amount determining unit includes:

The embodiment of the application also provides electronic equipment, which comprises a processor, a communication interface, a memory and a communication bus, wherein the processor and the communication interface, and the memory are communicated with each other through the communication bus;

a memory for storing a computer program;

a processor for implementing the steps of the method for controlling crystal growth as described in any one of figures 1 to 2 when executing the program stored on the memory.

The present embodiments also provide a computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of a method of controlling crystal growth as described in any of fig. 1 to 2.

Fig. 4 shows a schematic structural diagram of a crystal growth control device provided in an embodiment of the present application, and as shown in fig. 4, the control device includes a crucible 401, a furnace body 402, and a CCD camera 403, where the crucible 401 includes a silicon melt 4011 and a seed crystal 4012, and an aperture is located at a junction between the seed crystal 4012 and a liquid surface of the silicon melt 4011. The crucible 401 rotates along the arrow direction, the position of the CCD camera 403 needs to meet the requirement of measuring the crystal diameter, aperture width, brightness of the temperature measuring point, etc. in the crucible 401 in the furnace body 402, so the position of the CCD camera 403 needs to be kept parallel to the crystal as much as possible, for example, the angular deviation may be less than or equal to ±5°, and the field center of the CCD camera 403 and the seed crystal center are on the same axis, so as to reduce the measurement error, alternatively, the measurement error may be corrected by a double-sided image correction algorithm, but the image should be kept within a certain inclination angle.

Based on the illustration in fig. 4, the control method for crystal growth provided in the embodiment of the present application is implemented as follows:

after the process step of automatic temperature adjustment is completed, determining to enter a seeding process according to the thermal field state, and at the moment, starting diameter control and temperature control in the seeding process;

wherein the diameter control includes:

an image in the furnace body 402 is acquired based on an image acquisition visual algorithm through a CCD camera 403 on the side surface of the furnace body 402, and diameter pixels and aperture pixels in the seeding process are determined according to the image.

For example, a CCD camera 403 is used to obtain an image in the furnace body 402, and the number of diameter pixels in the seeding process is determined to be 50, and the number of aperture pixels is determined to be 20.

The real-time diameter of the crystal, and the aperture width of the aperture, is determined from the diameter pixel, aperture pixel, and pixel calibration relationship.

If the corresponding relation between the length (unit: millimeter/mm) and the number of pixels in the pixel calibration relation is 1:10, the real-time diameter of the crystal is 5mm, and the aperture width is 2mm.

The diameter difference between the real-time diameter and the target diameter is determined.

If the target diameter is 4.5mm, the diameter difference Δd=0.5 mm.

The rate of change of the aperture width in the aperture measurement period is determined.

If the aperture width is changed from 3mm to 2mm in the aperture measurement period 10s, the aperture width change rate is-0.1 mm/s.

And a PID control algorithm is adopted, a first pull speed adjustment amount is determined according to the diameter difference, the diameter proportional coefficient, the diameter integral coefficient and the pull speed integral period, and a second pull speed adjustment amount is determined according to the aperture width change rate and the diameter differential coefficient.

If the diameter scaling factor p=60, the diameter integration factor i=5, and the pull rate integration period is integrated once per second, i.e. 1mm/h is accumulated per second, the pull rate first adjustment amount is Δd×p+Δd×i×t=0.5×60+0.5×5×1=32.5 mm/h.

The diameter differential coefficient d=80, the pull rate second adjustment amount is 0.1×80= -8mm/h.

And determining the total adjustment amount of the pull speed according to the first adjustment amount of the pull speed and the second adjustment amount of the pull speed.

For example, the first pull rate adjustment amount and the second pull rate adjustment amount are added to determine that the total pull rate adjustment amount is 32.5-8=24.5 mm/h.

And determining the upper limit of the pulling speed of the single crystal, the lower limit of the pulling speed of the single crystal and the safe pulling speed, and adjusting the pulling speed adjusting quantity of the single crystal according to the total pulling speed adjusting quantity so as to realize the diameter control of the crystal.

For example, on the basis that the pulling rate of the single crystal is 180mm/h, the pulling rate of the single crystal is adjusted according to the total adjustment amount of the pulling rate of 24.5mm/h, the adjustment result is smaller than or equal to the upper limit of the pulling rate of the single crystal, the diameter change of the crystal is monitored in real time in the adjustment process, and the pulling rate of the single crystal is adjusted to be the safe pulling rate when the diameter of the crystal triggers the safe pulling rate.

Wherein the temperature control includes:

the real-time brightness of at least two temperature measuring points on the liquid surface of the silicon melt 4011 in the crucible 401 and the brightness change rate in the brightness measuring period are measured by a CCD camera 403 on the side of the furnace body 402.

For example, the brightness values of 10 temperature measuring points on the liquid surface of the silicon melt 4011 are collected by a CCD camera 403 and are respectively [70,65,66,68,60,64,66,68,63,67], and the brightness values of the 10 temperature measuring points are fitted to obtain real-time brightness (SUM (1:10) -70-60)/8= 65.875;

the brightness measurement period is 1 minute, the liquid level brightness is changed from 65 to 64, and the brightness change rate c= -0.016/s.

A luminance difference between the real-time luminance and the target luminance is determined.

For example, if the target luminance is 60, the luminance difference is Δc=5.875.

And determining a first rotating speed adjustment amount according to the brightness difference and the temperature proportional coefficient and determining a second rotating speed adjustment amount according to the brightness change rate and the temperature differential coefficient by adopting a PD control algorithm.

If the temperature proportionality coefficient p=0.05 and the temperature differential coefficient d=10, the first rotation speed adjustment amount is Δc×p=0.29 rpm, and the second rotation speed adjustment amount is c×d= -0.16rpm.

And determining the total rotation speed adjustment amount according to the first rotation speed adjustment amount and the second rotation speed adjustment amount.

For example, the total rotational speed adjustment amount is 0.13rpm, which is the sum of the rotational speed first adjustment amount and the rotational speed second adjustment amount.

And determining a single adjustment amount and a rotation speed adjustment period for adjusting the rotation speed of the crucible, determining the adjustment times according to the single adjustment amount and the total rotation speed adjustment amount, and determining the adjustment time according to the adjustment times and the rotation speed adjustment period.

If the single adjustment amount is 0.1rpm and the adjustment period is 30s, the adjustment times are determined to be 2 times according to the total rotation speed adjustment amount of 0.13rpm, and the adjustment time period is 60s.

And adjusting the rotating speed of the crucible according to the adjustment time length and the adjustment times so as to realize temperature control.

When the rotating speed of the crucible is adjusted, the servo motor has higher control precision, for example, the control precision can be 0.01rpm, so that the adjustment precision in temperature control is ensured, overshoot, fluctuation and the like caused by low adjustment precision are avoided, or the problem of crystal breakage caused by overlarge adjustment amplitude of the rotating speed of the crucible is avoided. In addition, the total amount of the rotation speed of the crucible can be limited, for example, the total amount of the rotation speed of the crucible cannot exceed + -R, so that the phenomenon that the efficiency or yield of crystal preparation is affected due to the fact that the rotation speed of the crucible after the adjustment is overlarge or oversized is avoided.

For example, the crucible rotation speed is adjusted twice within 60 seconds on the basis of the crucible rotation speed being 7rpm, and the adjustment amount of the crucible rotation speed is less than or equal to + -1 rpm until the crucible rotation speed reaches 7.13 rpm.

It should be noted that, for simplicity of description, the method embodiments are shown as a series of acts, but it should be understood by those skilled in the art that the embodiments are not limited by the order of acts described, as some steps may occur in other orders or concurrently in accordance with the embodiments. Further, those skilled in the art will appreciate that the embodiments described in the specification are presently preferred, and that the acts referred to are not necessarily all required for the embodiments of the present application.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

From the above description of the embodiments, it will be clear to those skilled in the art that the above-described embodiment method may be implemented by means of software plus a necessary general hardware platform, but of course may also be implemented by means of hardware, but in many cases the former is a preferred embodiment. Based on such understanding, the technical solution of the present application may be embodied essentially or in a part contributing to the prior art in the form of a software product stored in a storage medium (such as ROM/RAM, magnetic disk, optical disk), including several instructions for causing a terminal (which may be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to perform the method described in the embodiments of the present application.

The embodiments of the present application have been described above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those of ordinary skill in the art without departing from the spirit of the present application and the scope of the protection of the claims, which fall within the protection of the present application.

Claims

1. A method for controlling crystal growth, the method comprising:

collecting the real-time brightness of the liquid level;

determining a brightness change rate in a brightness measurement period;

acquiring a real-time diameter and an aperture width;

determining a rate of change of aperture width in a width measurement period;

2. The method of claim 1, wherein said adjusting the crucible rotation speed for temperature control based on said difference in brightness, said rate of change in brightness, said temperature scaling factor, said temperature differentiation factor comprises:

3. The method of claim 1, wherein said adjusting the single crystal pulling rate for diameter control based on said diameter difference, said aperture width change rate, said diameter scaling factor, said diameter integration factor, said diameter differentiation factor comprises:

4. The method of claim 1, wherein the acquiring the real-time brightness of the liquid surface comprises:

5. The method according to claim 2, wherein adjusting the crucible rotation speed according to the first rotation speed adjustment amount and the second rotation speed adjustment amount comprises:

6. The method of claim 1, wherein the acquiring the real-time diameter and aperture width comprises:

acquiring diameter pixels and aperture pixels in the seeding process;

7. A method according to claim 3, wherein said determining a first pull rate adjustment based on said diameter difference, said diameter scaling factor, and said diameter integration factor comprises:

8. A crystal growth control device, the device comprising:

the temperature control module includes:

the diameter control module includes:

9. The electronic equipment is characterized by comprising a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory are communicated with each other through the communication bus;

a memory for storing a computer program;

a processor for implementing the steps of the crystal growth control method according to any one of claims 1 to 7 when executing a program stored in a memory.

10. A computer-readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, implements the steps of the crystal growth control method according to any one of claims 1 to 7.