阅读说明：本技术 一种用于放肩过程的晶体生长控制方法、装置、系统及计算机存储介质 (Crystal growth control method, device and system for shouldering process and computer storage medium ) 是由 邓先亮 于 2019-03-11 设计创作，主要内容包括：本发明提供一种用于放肩过程的晶体生长控制方法、装置、系统及计算机存储介质,所述方法包括：预先设置放肩过程不同阶段的晶体生长角度设定值和所述放肩过程不同阶段的晶体生长工艺参数的设定值；获得所述放肩过程不同阶段的晶体直径,并计算获得晶体直径的变化值和晶体长度的变化值,并利用所述晶体直径的变化值与所述晶体长度的变化值之间的比值计算晶体生长角度值；将所述晶体生长角度值与所述晶体生长角度设定值进行比较,得到差值,并将所述差值作为PID算法的输入变量；通过PID算法计算晶体生长工艺参数的调节值,作为PID算法的输出变量；将所述晶体生长工艺参数的调节值和所述晶体生长工艺参数的设定值相加,得到实际长晶过程的工艺参数。(The invention provides a crystal growth control method, a device and a system for a shouldering process and a computer storage medium, wherein the method comprises the following steps: presetting crystal growth angle set values at different stages of the shouldering process and set values of crystal growth process parameters at different stages of the shouldering process; obtaining crystal diameters of different stages of the shouldering process, calculating to obtain a crystal diameter variation value and a crystal length variation value, and calculating a crystal growth angle value by using a ratio between the crystal diameter variation value and the crystal length variation value; comparing the crystal growth angle value with the crystal growth angle set value to obtain a difference value, and taking the difference value as an input variable of a PID algorithm; calculating the adjusting value of the crystal growth process parameter through a PID algorithm as an output variable of the PID algorithm; and adding the adjusting value of the crystal growth technological parameter and the set value of the crystal growth technological parameter to obtain the technological parameter of the actual crystal growth process.)

1. A crystal growth control method for a shouldering process, comprising the steps of:

presetting crystal growth angle set values at different stages of the shouldering process and set values of crystal growth process parameters at different stages of the shouldering process;

obtaining crystal diameters of different stages of the shouldering process, calculating to obtain a crystal diameter variation value and a crystal length variation value, and calculating a crystal growth angle value by using a ratio between the crystal diameter variation value and the crystal length variation value;

comparing the crystal growth angle value with the crystal growth angle set value to obtain a difference value, and taking the difference value as an input variable of a PID algorithm;

calculating the adjusting value of the crystal growth process parameter through a PID algorithm as an output variable of the PID algorithm;

and adding the adjusting value of the crystal growth technological parameter and the set value of the crystal growth technological parameter to obtain the technological parameter of the actual crystal growth process, thereby ensuring the consistency of the diameter change during each shouldering and further ensuring the stability of the crystal growth quality of different batches.

2. The method of claim 1, wherein calculating the crystal growth angle value comprises:

θ’＝2arctan(△Dia/△L)

wherein, theta' represents the value of crystal growth angle, Delta Dia represents the variation value of crystal diameter, and Delta L represents the variation value of crystal length.

3. The method of claim 1, wherein the crystal growth process parameters of the shouldering process include a pull rate and/or a temperature.

4. The method of claim 1, wherein the different stages of the shouldering process comprise different shouldering times or different crystal lengths.

5. The method of claim 1, wherein the crystal diameters at different stages of the shouldering process are obtained by a diameter measuring device.

6. A crystal growth control apparatus for use in a shouldering process, the apparatus comprising:

the presetting module is used for presetting crystal growth angle set values at different stages of the shouldering process and crystal growth process parameter set values at different stages of the shouldering process;

the diameter measuring device is used for obtaining the crystal diameters at different stages of the shouldering process, calculating to obtain a crystal diameter variation value and a crystal length variation value, and calculating a crystal growth angle value by using the ratio of the crystal diameter variation value to the crystal length variation value;

the comparison module is used for comparing the crystal growth angle value with the crystal growth angle set value to obtain a difference value;

the PID control module is used for taking the difference value as an input variable of the PID control module, calculating a regulating value of a crystal growth process parameter through a PID algorithm and taking the regulating value as an output variable of the PID control module;

and the process parameter setting module is used for adding the adjusting value of the crystal growth process parameter and the set value of the crystal growth process parameter to obtain the process parameter of the actual crystal growth process.

7. The crystal growth control apparatus of claim 6, wherein the crystal growth process parameters of the shouldering process include a pull rate and/or a temperature.

8. The crystal growth control apparatus of claim 6, wherein the different stages of the shouldering process comprise different shouldering times or different crystal lengths.

9. A crystal growth control system for a shouldering process comprising a memory, a processor and a computer program stored on the memory and run on the processor, wherein the processor when executing the computer program implements the steps of the method of any one of claims 1 to 5.

10. A computer storage medium having a computer program stored thereon, wherein the computer program, when executed by a computer, implements the steps of the method of any of claims 1 to 5.

Technical Field

The invention relates to the field of crystal growth, in particular to a crystal growth control method, a crystal growth control device, a crystal growth control system and a computer storage medium for a shouldering process.

Background

Single crystal silicon is a semiconductor material commonly used in the fabrication of integrated circuits and other electronic components. In the process of preparing the silicon single crystal, a seed crystal with a smaller diameter is mainly immersed into silicon melt, and dislocation is discharged by seeding to grow a section of fine crystal with a smaller diameter so as to achieve the purpose of growing a zero dislocation crystal. Then, the crystal grows from fine grains to a target diameter through a shouldering process, and then the crystal with the required size is obtained through equal-diameter growth.

The shouldering process is a more key technological process in the crystal growth process and is the basis for obtaining crystals with target diameters. At present, the main method adopted is to use a method of combining the crystal pulling speed and the temperature reduction degree to continuously increase the diameter of the crystal so as to achieve the target diameter. In the shouldering process, the change of the pulling speed and the temperature is mainly determined by the shouldering starting time or the shouldering length, so that the pulling speed and the temperature at different stages need to be matched in the shouldering process. However, in the actual crystal growth process, because the service time of the thermal field, the seeding temperature, the service life of the heater and the like have some differences in each crystal growth process, if the temperature and the crystal pulling speed can not be adjusted in time, the crystal structure can be lost in the shouldering process. In addition, variations in different growth conditions can also lead to variations in the shouldering process, which is the most difficult part of the development process of the growth process, requiring numerous attempts to find the appropriate temperature and pull rate settings. Meanwhile, the crystal growth process is the most difficult part to control, and it is very difficult to make the shouldering consistent every time.

The invention provides a crystal growth control method, a crystal growth control device, a crystal growth control system and a computer storage medium for a shouldering process, and aims to solve the technical problems.

Disclosure of Invention

In this summary, concepts in a simplified form are introduced that are further described in the detailed description. This summary of the invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

The invention provides a crystal growth control method for a shouldering process, which comprises the following steps:

presetting crystal growth angle set values at different stages of the shouldering process and set values of crystal growth process parameters at different stages of the shouldering process;

obtaining crystal diameters of different stages of the shouldering process, calculating to obtain a crystal diameter variation value and a crystal length variation value, and calculating a crystal growth angle value by using a ratio between the crystal diameter variation value and the crystal length variation value;

comparing the crystal growth angle value with the crystal growth angle set value to obtain a difference value, and taking the difference value as an input variable of a PID algorithm;

calculating the adjusting value of the crystal growth process parameter through a PID algorithm as an output variable of the PID algorithm;

and adding the adjusting value of the crystal growth technological parameter and the set value of the crystal growth technological parameter to obtain the technological parameter of the actual crystal growth process, thereby ensuring the consistency of the diameter change during each shouldering and further ensuring the stability of the crystal growth quality of different batches.

Further, the method for calculating the crystal growth angle value comprises the following steps:

θ’＝2arctan(△Dia/△L)

wherein, theta' represents the value of crystal growth angle, Delta Dia represents the variation value of crystal diameter, and Delta L represents the variation value of crystal length.

Further, the crystal growth process parameters of the shouldering process comprise a pulling speed and/or a temperature.

Further, different stages of the shouldering process comprise different shouldering time or different crystal lengths.

Further, the crystal diameters of different stages of the shouldering process are obtained by a diameter measuring device.

The present invention also provides a crystal growth control apparatus for a shouldering process, the apparatus comprising:

the presetting module is used for presetting crystal growth angle set values at different stages of the shouldering process and crystal growth process parameter set values at different stages of the shouldering process;

the diameter measuring device is used for obtaining the crystal diameters at different stages of the shouldering process, calculating to obtain a crystal diameter variation value and a crystal length variation value, and calculating a crystal growth angle value by using the ratio of the crystal diameter variation value to the crystal length variation value;

the comparison module is used for comparing the crystal growth angle value with the crystal growth angle set value to obtain a difference value;

the PID control module is used for taking the difference value as an input variable of the PID control module, calculating a regulating value of a crystal growth process parameter through a PID algorithm and taking the regulating value as an output variable of the PID control module;

and the process parameter setting module is used for adding the adjusting value of the crystal growth process parameter and the set value of the crystal growth process parameter to obtain the process parameter of the actual crystal growth process.

Further, the crystal growth process parameters of the shouldering process comprise a pulling speed and/or a temperature.

Further, different stages of the shouldering process comprise different shouldering time or different crystal lengths.

The invention also provides a crystal growth control system for the shouldering process, which comprises a memory, a processor and a computer program stored on the memory and running on the processor, wherein the processor realizes the steps of the method when executing the computer program.

The invention also provides a computer storage medium having a computer program stored thereon, wherein the computer program, when executed by a computer, implements the steps of the above-described method.

In summary, according to the crystal growth control method, the crystal growth control device, the crystal growth control system and the computer storage medium for the shouldering process, the diameter change of the shouldering process is controlled and adjusted by adopting the PID algorithm, the crystal diameter change of the shouldering process is controlled by finely adjusting the crystal growth process parameters, the influence of the small change of the thermal field on the shouldering process is overcome, the repeatability of the crystal shape and the crystal shoulder shape grown each time is high, the consistency of the change value of the crystal diameter in the shouldering process is ensured, the accuracy, the repeatability and the process stability of the shouldering process are improved, a foundation is established for the accuracy, the stability and the repeatability of the whole crystal growth process, and the crystal quality grown each time is kept consistent.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail embodiments of the present invention with reference to the attached drawings. The accompanying drawings are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings, like reference numbers generally represent like parts or steps.

In the drawings:

FIG. 1 is a schematic view of a crystal growth furnace used in a crystal growth control method according to an embodiment of the present invention;

FIG. 2 is a schematic view showing a silicon single crystal ingot obtained by a crystal growth control method according to an embodiment of the present invention;

FIG. 3 shows a main process flow diagram of a crystal growth control method for the shouldering process according to an embodiment of the invention;

FIG. 4 shows a schematic diagram of a crystal growth control method for a shouldering process according to an embodiment of the invention;

FIG. 5 shows a schematic block diagram of a crystal growth control apparatus for a shouldering process according to an embodiment of the present invention;

FIG. 6 shows a schematic block diagram of a crystal growth control system for a shouldering process according to an embodiment of the invention.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the invention.

In order to provide a thorough understanding of the present invention, detailed steps will be set forth in the following description in order to explain the crystal growth control method for the shouldering process proposed by the present invention. It will be apparent that the invention may be practiced without limitation to specific details that are within the skill of one of ordinary skill in the semiconductor arts. The following detailed description of the preferred embodiments of the invention, however, the invention is capable of other embodiments in addition to those detailed.

It will be understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

FIG. 1 is a schematic view showing a crystal growth furnace used in a crystal growth control method according to an embodiment of the present invention, and the crystal growth furnace for growing a silicon single crystal by the Czochralski method, as shown in FIG. 1, includes a furnace body 101, and a heating device and a pulling device are provided in the furnace body 101. The heating device includes a quartz crucible 102, a graphite crucible 103, and a heater 104. The quartz crucible 102 is used for holding a silicon material, such as polysilicon. Where the silicon charge is heated to silicon melt 105. The graphite crucible 103 is wrapped around the outside of the quartz crucible 102 for providing support to the quartz crucible 102 during heating, and the heater 104 is disposed outside the graphite crucible 103. A heat shield 106 is arranged above the quartz crucible 102, and the heat shield 106 is provided with a downward-extending inverted cone-shaped shield surrounding the growing area of the silicon single crystal 107, so that direct heat radiation of the heater 104 and the high-temperature silicon melt 105 to the growing single crystal silicon ingot 107 can be blocked, and the temperature of the single crystal silicon ingot 107 can be reduced. Meanwhile, the heat shield can also enable the downward-blown protective gas to be intensively and directly sprayed to the vicinity of a growth interface, so that the heat dissipation of the monocrystalline silicon crystal bar 107 is further enhanced. The side wall of the furnace body 101 is also provided with a heat insulating material, such as carbon felt.

The pulling device comprises a seed shaft 108 and a crucible shaft 109 which are vertically arranged, the seed shaft 108 is arranged above the quartz crucible 102, the crucible shaft 109 is arranged at the bottom of the graphite crucible 103, a seed crystal is arranged at the bottom of the seed shaft 108 through a clamp, and the top of the seed shaft is connected with a seed shaft driving device, so that the seed shaft can rotate and pull upwards slowly. The bottom of the crucible shaft 109 is provided with a crucible shaft driving device, so that the crucible shaft 109 can drive the crucible to rotate.

When single crystal growth is performed, firstly, a silicon material is put into the quartz crucible 102, then the crystal growth furnace is closed and vacuumized, and protective gas is filled into the crystal growth furnace. Illustratively, the shielding gas is argon gas with a purity of 97% or more, a pressure of 5mbar to 100mbar, and a flow rate of 70slpm to 200 slpm. Then, heater 104 is turned on and heated to a melting temperature of 1420 ℃ or higher to melt the entire silicon material into silicon melt 105.

Next, the seed crystal is immersed in silicon melt 105, rotated and slowly pulled by seed shaft 108 so that silicon atoms grow along the seed crystal as single crystal silicon ingot 107. The seed crystal is formed by cutting or drilling a silicon single crystal with a certain crystal orientation, the common crystal orientation is <100>, <111>, <110> and the like, and the seed crystal is generally a cylinder. The crystal growth process of the monocrystalline silicon crystal bar 107 sequentially comprises the stages of seeding, shouldering, shoulder rotating, diameter equalizing and ending.

Specifically, the seeding stage is first performed. That is, after silicon melt 105 is stabilized to a certain temperature, the seed crystal is immersed in the silicon melt and raised at a certain pulling rate to grow silicon atoms into a narrow neck with a certain diameter along the seed crystal until the narrow neck reaches a predetermined length. The main function of the seeding process is to eliminate dislocation defects formed by the monocrystalline silicon due to thermal shock, and to utilize the supercooling degree of the crystallization front to drive silicon atoms to be sequentially arranged on the silicon solid at the solid-liquid interface to form the monocrystalline silicon. Illustratively, the drawing speed is 1.5mm/min-4.0m/min, the length of the thin neck is 0.6-1.4 times of the diameter of the crystal bar, and the diameter of the thin neck is 5-7 mm.

Then, entering a shouldering stage, after the thin neck reaches a preset length, slowing down the speed of pulling the seed crystal upwards, and slightly reducing the temperature of the silicon melt, wherein the temperature is reduced to promote the lateral growth of the single crystal silicon, even if the diameter of the single crystal silicon is increased, the process is called a shouldering stage, and a conical crystal bar formed in the shouldering stage is a shouldered section of the crystal bar as shown in figure 2.

Then, the shoulder turning stage is entered. When the diameter of the silicon single crystal is increased to a target diameter, the heating power of the heater 104 is increased, the temperature of the silicon melt is increased, and the speed of pulling up the seed crystal, the speed of rotation, the rotation speed of the quartz crucible, and the like are adjusted to suppress the lateral growth of the silicon single crystal, promote the longitudinal growth thereof, and make the silicon single crystal grow nearly in an equal diameter.

Then, the equal diameter stage is entered. When the diameter of the monocrystalline silicon ingot reaches a preset value, the diameter-equaling stage is carried out, and as shown in fig. 2, the cylindrical ingot formed at the stage is the diameter-equaling section of the ingot. Specifically, the crucible temperature, the crystal pulling speed, the crucible rotating speed and the crystal rotating speed are adjusted to stabilize the growth rate and keep the crystal diameter unchanged until the crystal pulling is finished. The isodiametric process is the main stage of growth of single crystal silicon, and can grow for dozens of hours or even more than one hundred hours.

And finally, entering a final stage. At the end of the run, the lift rate is increased and the temperature of silicon melt 105 is increased to gradually reduce the diameter of the ingot to a conical shape that eventually leaves the liquid surface when the tip is sufficiently small. And raising the finished crystal bar to the upper furnace chamber, cooling for a period of time, and taking out to finish a growth cycle.

In several stages of the crystal growth process of the monocrystalline silicon, the shouldering stage is a more critical process in the crystal growth process and is the basis for obtaining crystals with target diameters. At present, the main method adopted is to use a method of combining the crystal pulling speed and the temperature reduction degree to continuously increase the diameter of the crystal so as to achieve the target diameter. In the shouldering process, the change of the pulling speed and the temperature is mainly determined by the shouldering starting time or the shouldering length, so that the pulling speed and the temperature at different stages need to be matched in the shouldering process. However, in the actual crystal growth process, because the service time of the thermal field, the seeding temperature, the service life of the heater and the like have some differences in each crystal growth process, if the temperature and the crystal pulling speed can not be adjusted in time, the crystal structure can be lost in the shouldering process. In addition, variations in different growth conditions can also lead to variations in the shouldering process, which is the most difficult part of the development process of the growth process, requiring numerous attempts to find the appropriate temperature and pull rate settings. Meanwhile, the crystal growth process is the most difficult part to control, and it is very difficult to make the shouldering consistent every time.

In view of the above problems, the present invention proposes a crystal growth control method for a shouldering process, as shown in fig. 3, which includes the following main steps:

step S301: presetting crystal growth angle set values at different stages of the shouldering process and set values of crystal growth process parameters at different stages of the shouldering process;

step S302: obtaining crystal diameters of different stages of the shouldering process, calculating to obtain a crystal diameter variation value and a crystal length variation value, and calculating a crystal growth angle value by using a ratio between the crystal diameter variation value and the crystal length variation value;

step S303: comparing the crystal growth angle value with the crystal growth angle set value to obtain a difference value, and taking the difference value as an input variable of a PID algorithm;

step S304: calculating the adjusting value of the crystal growth process parameter through a PID algorithm as an output variable of the PID algorithm;

step S305: and adding the adjusting value of the crystal growth technological parameter and the set value of the crystal growth technological parameter to obtain the technological parameter of the actual crystal growth process, thereby ensuring the consistency of the diameter change during each shouldering and further ensuring the stability of the crystal growth quality of different batches.

Specifically, in step S301, the crystal growth angle set value and the set value θ of the pull rate and/or the set value of the temperature at different shouldering times or different crystal lengths of the shouldering process are set in advance.

In step S302, crystal diameters at different shouldering times or different crystal lengths in the shouldering process are obtained, a variation value of the obtained crystal diameter and a variation value of the obtained crystal length are calculated, and a crystal growth angle value is calculated using a ratio between the variation value of the crystal diameter and the variation value of the crystal length.

In the invention, the crystal diameters at different shouldering times or different crystal lengths of the shouldering process are obtained by a diameter measuring device. A CCD (Charge coupled Device) camera can be used to capture images of the junction between the monocrystalline silicon ingot 107 and the silicon melt 105 in the crystal growth furnace, and then the images are processed by a computer to obtain the diameter of the monocrystalline silicon ingot 107 and fed back to the control system to control the crystal growth. Specifically, during crystal growth, a bright ring is generated at the solid-liquid interface of single crystal silicon ingot 107 and silicon melt 105 due to latent heat release. The CCD camera acquires the image signal of the bright ring, and transmits the signal to the computer system after analog-to-digital conversion, and the image processing program in the computer system processes the single crystal growth image to acquire the measured diameter of the single crystal silicon ingot 107. As an example, a method of acquiring a measured diameter of a single crystal silicon ingot 107 from an image signal acquired by a CCD camera includes: extracting a bright ring at a solid-liquid interface by an image processing program to obtain a crystal profile; fitting the crystal contour to obtain an elliptical boundary; correcting the elliptical boundary to a circular boundary; and (3) randomly selecting three pixel points on the circular boundary, substituting coordinate values of the three pixel points into a circular coordinate formula, forming an equation and solving, and then calculating to obtain the circle center coordinate and the diameter of the crystal.

Illustratively, the relationship between the value of the crystal growth angle θ' and the value of the change in crystal diameter Δ Dia and the value of the change in crystal length Δ L between different shouldering times is:

tan (θ'/2) ═ Δ Dia/Δl (equation 1)

It can thus be derived:

θ' ═ 2arctan (Δ Dia/. DELTA.L) (equation 2)

In step S303, the crystal growth angle value θ' is compared with the crystal growth angle set value θ to obtain a difference Δ θ, and the difference Δ θ is used as an input variable of the PID algorithm.

Δ θ ═ θ' - θ (equation 3)

In step S304, the pull rate adjustment value and/or the temperature adjustment value are calculated by the PID algorithm as output variables of the PID algorithm.

Wherein the PID algorithm is controlled according to the proportion (P), the integral (I) and the derivative (D) of the deviation. The proportional control can quickly reflect errors so as to reduce the errors, but the proportional control cannot eliminate steady-state errors, and the increase of proportional gain can cause the instability of a system; the integral control has the effects that as long as the system has errors, the integral control effect is continuously accumulated, and the control quantity is output to eliminate the errors, so that as long as enough time is available, the integral control can completely eliminate the errors, but the integral effect is too strong, so that the overshoot of the system is increased, and even the system oscillates; the differential control can reduce overshoot, overcome oscillation, improve the stability of the system, accelerate the dynamic response speed of the system, and reduce the adjustment time, thereby improving the dynamic performance of the system.

Finally, in step S305, the adjustment value of the pulling rate and the set value of the pulling rate are added to obtain the pulling rate in the actual crystal growth process; and adding the temperature regulating value and the temperature set value to obtain the temperature in the actual crystal growth process.

FIG. 4 shows a schematic diagram of the crystal growth control method for the shouldering process of the present invention, as shown in FIG. 4, with the input to the PID algorithm being the difference between the crystal growth angle value and the crystal growth angle setpoint value; the PID algorithm outputs a pull rate adjustment value and a temperature adjustment value, the pull rate adjustment value is added to a pull rate set value to obtain an actual pull rate, and the temperature adjustment value is added to a temperature set value to obtain an actual temperature.

According to the crystal growth control method for the shouldering process, the difference value between the crystal growth angle value and the crystal growth angle set value is used as the input variable of the PID algorithm, the crystal growth process parameter is calculated through the PID algorithm and is used as the output variable of the PID algorithm, the diameter change of the shouldering process is controlled and adjusted through the PID algorithm, the crystal diameter change of the shouldering process is controlled through fine adjustment of the crystal growth process parameter, the influence of the small change of a thermal field on the shouldering process is overcome, the crystal shape and the crystal shoulder shape which grow each time are high in repeatability, the change value of the crystal diameter in the shouldering process is ensured to be consistent, the accuracy, the repeatability and the process stability of the shouldering process are improved, a basis is established for the accuracy, the stability and the repeatability of the whole crystal growth process, and the crystal quality which grows each time is consistent.

As shown in fig. 5, the crystal growth control apparatus 500 for the shouldering process according to the embodiment of the present invention includes a presetting module 501, a diameter measuring device 502, a comparing module 503, a PID control module 504 and a process parameter setting module 505.

The presetting module 501 is used for presetting crystal growth angle set values at different stages of the shouldering process and crystal growth process parameter set values at different stages of the shouldering process;

the diameter measuring device 502 is used for obtaining the crystal diameters at different stages of the shouldering process, calculating the change value of the obtained crystal diameter and the change value of the crystal length, and calculating the crystal growth angle value by using the ratio of the change value of the crystal diameter to the change value of the crystal length;

a comparing module 503, configured to compare the crystal growth angle value with the crystal growth angle set value to obtain a difference value;

the PID control module 504 is used for taking the difference value as an input variable of the PID control module, calculating a regulating value of a crystal growth process parameter through a PID algorithm, and taking the regulating value as an output variable of the PID control module;

and a process parameter setting module 505 for adding the adjustment value of the crystal growth process parameter and the set value of the crystal growth process parameter to obtain the process parameter of the actual crystal growth process.

Specifically, the presetting module 501 presets the crystal growth angle set value θ, the crystal pulling speed set value and/or the temperature set value at different shouldering times or different crystal lengths in the shouldering process; the diameter measuring device 502 obtains the crystal diameters at different stages of the shouldering process, calculates and obtains a crystal diameter variation value delta Dia and a crystal length variation value delta L, and calculates a crystal growth angle value theta' to be 2arctan (delta Dia/delta L) by using a ratio delta Dia/delta L between the crystal diameter variation value and the crystal length variation value; the comparison module 503 compares the crystal growth angle value θ' with the crystal growth angle set value θ to obtain a difference value Δ θ; the PID control module 504 takes the difference value Δ θ as an input variable of a PID algorithm, and calculates a pull rate adjustment value and/or a temperature adjustment value as an output variable of the PID control module through the PID algorithm; the process parameter setting module 505 adds the adjustment value of the crystal pulling speed and the set value of the crystal pulling speed to obtain the crystal pulling speed in the actual crystal growing process, and adds the adjustment value of the temperature and the set value of the temperature to obtain the temperature in the actual crystal growing process.

Further, different stages of the shouldering process comprise different shouldering times or different crystal lengths.

Illustratively, the diameter measuring device 502 is a CCD camera. The CCD camera is used for collecting images at the three-phase intersection of the monocrystalline silicon crystal rod 107 and the silicon melt 105 in the crystal growing furnace, and then the images are processed by a computer to obtain the diameter of the monocrystalline silicon crystal rod 107 and fed back to the control system to control crystal growing. Specifically, during crystal growth, a bright ring is generated at the solid-liquid interface of single crystal silicon ingot 107 and silicon melt 105 due to latent heat release. The CCD camera acquires the image signal of the bright ring, and transmits the signal to the computer system after analog-to-digital conversion, and the image processing program in the computer system processes the single crystal growth image to acquire the measured diameter of the single crystal silicon ingot 107. As an example, a method of acquiring a measured diameter of a single crystal silicon ingot 107 from an image signal acquired by a CCD camera includes: extracting a bright ring at a solid-liquid interface by an image processing program to obtain a crystal profile; fitting the crystal contour to obtain an elliptical boundary; correcting the elliptical boundary to a circular boundary; and (3) randomly selecting three pixel points on the circular boundary, substituting coordinate values of the three pixel points into a circular coordinate formula, forming an equation and solving, and then calculating to obtain the circle center coordinate and the diameter of the crystal.

FIG. 6 shows a schematic block diagram of a crystal growth control system 600 for a shouldering process according to an embodiment of the invention. Crystal growth control system 600 includes memory 610 and processor 620.

The memory 610 stores program codes for implementing respective steps in a crystal growth control method for a shouldering process according to an embodiment of the present invention.

The processor 620 is configured to run the program codes stored in the memory 610 to execute the corresponding steps of the crystal growth control method for the shouldering process according to the embodiment of the present invention, and to implement the presetting module 501, the diameter measuring device 502, the comparing module 503, the PID control module 504 and the process parameter setting module 505 in the crystal growth control device for the shouldering process according to the embodiment of the present invention.

In one embodiment, the crystal growth control method for the shouldering process described above is performed when the program code is executed by the processor 620.

Further, according to an embodiment of the present invention, there is also provided a storage medium on which program instructions for executing the respective steps of the crystal growth control method for a shouldering process of an embodiment of the present invention are stored and for implementing the respective modules in the crystal growth control apparatus for a shouldering process according to an embodiment of the present invention are executed when the program instructions are executed by a computer or a processor. The storage medium may include, for example, a storage component of a tablet computer, a hard disk of a personal computer, Read Only Memory (ROM), Erasable Programmable Read Only Memory (EPROM), portable compact disc read only memory (CD-ROM), USB memory, or any combination of the above storage media. The computer readable storage medium can be any combination of one or more computer readable storage media, e.g., one containing computer readable program code for randomly generating sequences of action instructions and another containing computer readable program code for performing crystal growth control for the shouldering process.

In one embodiment, the computer program instructions, when executed by a computer, may implement the functional blocks of the crystal growth control apparatus for a shouldering process according to an embodiment of the present invention and/or may perform the crystal growth control method for a shouldering process according to an embodiment of the present invention.

In one embodiment, the computer program instructions, when executed by a computer, perform the above crystal growth control method for a shouldering process.

In summary, according to the crystal growth control method, the crystal growth control device, the crystal growth control system and the computer storage medium for the shouldering process, the diameter change of the shouldering process is controlled and adjusted by adopting the PID algorithm, the crystal diameter change of the shouldering process is controlled by finely adjusting the crystal growth process parameters, the influence of the small change of the thermal field on the shouldering process is overcome, the repeatability of the crystal shape and the crystal shoulder shape grown each time is high, the consistency of the change value of the crystal diameter in the shouldering process is ensured, the accuracy, the repeatability and the process stability of the shouldering process are improved, a foundation is established for the accuracy, the stability and the repeatability of the whole crystal growth process, and the crystal quality grown each time is kept consistent.

The present invention has been illustrated by the above embodiments, but it should be understood that the above embodiments are for illustrative and descriptive purposes only and are not intended to limit the invention to the scope of the described embodiments. Furthermore, it will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that many variations and modifications may be made in accordance with the teachings of the present invention, which variations and modifications are within the scope of the present invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.