A method of controlling a crystal furnace

Abstract

The application relates to the technical field of single crystal growth, and discloses a control method of a crystal furnace; the method comprises the following steps: obtaining basic operation parameters, determining whether the crystal furnace meets operation and maintenance control requirements, collecting comprehensive operation parameters of the crystal furnace in a collection period, predicting a crystal state value in a next collection period, determining whether to issue a control prompt, identifying control target data, formulating corresponding optimization control instructions, and controlling the crystal furnace to execute the optimization control instructions; compared with the prior art, the crystal state value in the next collection period can be accurately and in advance predicted according to the crystal furnace operation data in the last collection period, so that a low-quality phenomenon of the single crystal material can be in advance predicted, control instructions corresponding to the control target data can be formulated and executed, the crystal furnace can implement optimization control measures before the low-quality phenomenon of the crystal appears, and the problem of control lag caused by the real-time collection data real-time analysis and prediction mode can be effectively avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of single crystal growth, and more particularly to a method for controlling a crystal furnace. Background Art

[0002] A crystal furnace is a device used to melt polycrystalline materials and process them into single crystal materials. Since the various operating environments inside the crystal furnace change in real time, the real-time operating status of the crystal furnace is often difficult to maintain stable and controllable, which in turn leads to low-quality growth of single crystal materials and destroys the operating status of the crystal furnace. In order to maintain the stable operation of the crystal furnace and improve the growth quality of single crystal materials, it is necessary to accurately control the crystal furnace.

[0003] Patent application with reference publication number CN117626411A discloses a crystal furnace vacuum control system and a vacuum degree control method, which includes an acoustic wave sensor for collecting acoustic wave signals in the crystal furnace; a preprocessing module for preprocessing the collected acoustic wave signals and extracting characteristic parameters of the acoustic wave signals; an abnormality diagnosis module for judging whether there is an abnormality in the vacuum degree in the crystal furnace based on the characteristic parameters of the acoustic wave signals and outputting an abnormality diagnosis result; a prediction module for predicting the vacuum degree change trend in the crystal furnace based on the characteristic parameters of the acoustic wave signals, a set vacuum degree target value and the abnormality diagnosis result, and determining the vacuum degree adjustment requirement in the crystal furnace; and a control module for According to the vacuum degree adjustment requirements, the effective balance control parameters in the crystal furnace are calculated, including the on-off state of the vacuum pump, the opening of the valve, and the gas flow rate; the execution module is used to control the relevant equipment in the crystal furnace, including the vacuum pump, valve, and gas injection device, according to the effective balance control parameters, to adjust the vacuum degree in the crystal furnace. By collecting and analyzing the ionization signal in the crystal furnace, it can increase the information content and reliability of the vacuum degree diagnosis, and improve the accuracy and sensitivity of the vacuum degree diagnosis; by weighting the characteristic parameters of the ionization signal and the acoustic wave signal, it can comprehensively consider the influence of the two signals, obtain the comprehensive characteristic parameters of the vacuum degree, and realize the comprehensive diagnosis of vacuum degree anomalies;

[0004] The existing technology has the following deficiencies:

[0005] The existing control method of the crystal furnace collects various operating data in the crystal furnace in real time, and imports the collected operating data into a prediction model to predict the real-time operating status of the crystal furnace, thereby realizing the optimized control of the crystal furnace. Since the growth process of the single crystal material in the crystal furnace is continuous and uninterrupted, when the method of real-time data collection and real-time prediction of the operating status is adopted, only the operating status of the crystal furnace at the current moment can be predicted, and the operating status of the next upcoming moment cannot be predicted in advance, so that the corresponding control measures cannot be accurately and in advance, which makes the control measures of the crystal furnace have lags and reduces the control effect of the crystal furnace.

[0006] In view of this, the present invention proposes a control method for a crystal furnace to solve the above problems. Summary of the Invention

[0007] In order to overcome the above-mentioned defects of the prior art and to achieve the above-mentioned purpose, the present invention provides the following technical solution: a control method of a crystal furnace, applied to a control terminal, comprising:

[0008] S1: Obtain the basic operating parameters of the crystal furnace and determine whether the crystal furnace meets the operation and maintenance control requirements based on the safe operation and maintenance criteria; if it meets the operation and maintenance control requirements, execute S2; if it does not meet the operation and maintenance control requirements, repeat S1;

[0009] S2: dividing the acquisition period into acquisition periods from the acquisition cycle, and acquiring comprehensive operating parameters of the crystal furnace during the acquisition period, the comprehensive operating parameters including the local temperature increment, the furnace pressure decay rate, and the single crystal diameter constancy;

[0010] S3: Input the collected comprehensive operating parameters into a state prediction model that has been trained in advance to predict the crystal state value in the next collection period, predict the crystal state value in the next collection period, and determine whether to issue a control prompt; if not, repeat S3; if so, execute S4-S5;

[0011] S4: Identify control target data from the comprehensive operating parameters and formulate corresponding optimization control instructions, which include instructions for reducing the local temperature increment value, reducing the furnace pressure decay rate, and increasing the single crystal diameter constancy;

[0012] S5: Count the number of control target data, and control the crystal furnace to execute the optimized control instructions in combination with the execution priority until no control prompt is issued.

[0013] Furthermore, the basic operating parameters include the furnace temperature value and the furnace pressure value;

[0014] The safe operation and maintenance criteria are: there are no unqualified parameters in the basic operating parameters;

[0015] Methods for determining whether operation and maintenance control requirements are met include:

[0016] Compare the furnace temperature value with the lower temperature limit. When the furnace temperature value is less than the lower temperature limit, mark the furnace temperature value as an unqualified parameter.

[0017] Compare the furnace pressure value with the pressure lower limit value, and when the furnace pressure value is less than the pressure lower limit value, mark the furnace pressure value as an unqualified parameter;

[0018] Count the number of unqualified parameters. When the number of unqualified parameters reaches 0, it is determined that the operation and maintenance control requirements are met.

[0019] When the number of unqualified parameters is not 0, it is determined that the operation and maintenance control requirements are not met.

[0020] Furthermore, the method of dividing the collection period includes:

[0021] Use the timestamp to query the time when the crystal furnace first meets the operation and maintenance control requirements, and record it as the cycle start time;

[0022] The period between the start time of the cycle and the current time is recorded as the collection period;

[0023] Based on the preset unit time length, the collection period is divided into i consecutive collection periods, and the start and end times of the i collection periods are marked.

[0024] Furthermore, the method for obtaining the local temperature increment value includes:

[0025] Randomly mark p discontinuous moments in i acquisition periods to obtain p detection moments;

[0026] At p detection moments, a thermal infrared camera is used to capture real-time images of the interior of the crucible in the crystal furnace, obtaining p thermal infrared images;

[0027] Using computer vision technology, the position of the liquid surface of the polycrystalline material fluid and the position of the upper edge of the crucible in the thermal infrared image are identified to obtain a first boundary and a second boundary respectively;

[0028] Measuring the distance between the first boundary and the second boundary using a scale to obtain the remaining height value of the inner wall;

[0029] Take the remaining height of one-third of the inner wall as a unit length, take the first dividing line as the base point, and move vertically upward by a distance corresponding to the unit length to obtain the third boundary;

[0030] The area between the third boundary and the second boundary in the thermal infrared image is recorded as the inner wall area, and the area below the first boundary in the thermal infrared image is recorded as the fluid area;

[0031] Sequentially record the minimum temperature value of the inner wall area at p detection moments and the maximum temperature value of the fluid area at p detection moments to obtain p inner wall temperature values ​​and p fluid temperature values;

[0032] After subtracting the p inner wall temperature values ​​from the corresponding p fluid temperature values, p sub-incremental values ​​are obtained;

[0033] The expression for the sub-increment value is:

[0034] DZ zip =WD lip -WD nip ;

[0035] Where DZ zip is the pth sub-increment value in the i-th acquisition period, WD lip is the pth fluid temperature value in the ith acquisition period, WD nip is the pth inner wall temperature value in the i-th acquisition period;

[0036] Accumulate the p sub-incremental values ​​and average them to obtain i local temperature increment values;

[0037] The expression of the local temperature increment is:

[0038]

[0039] Where DZ jyi is the local temperature increment during the i-th acquisition period, DZ zia is the ath sub-increment value in the i-th acquisition period.

[0040] Furthermore, the method for obtaining the furnace pressure decay rate includes:

[0041] The pressure sensor is used to detect the furnace pressure corresponding to the start and end times of i acquisition periods, and obtain i starting furnace pressure values ​​and i ending furnace pressure values;

[0042] After subtracting the i starting furnace pressure values ​​from the i ending furnace pressure values ​​one by one, i attenuation values ​​are obtained;

[0043] The expression of the attenuation value is:

[0044] SJ zi =LY ksi -LY jsi ;

[0045] Where S Jzi is the attenuation value of the i-th acquisition period, LY ksi is the starting furnace pressure value of the i-th collection period, LY jsi is the ending furnace pressure value of the i-th collection period;

[0046] Compare the i attenuation values ​​with the duration corresponding to the acquisition period in turn to obtain i furnace pressure attenuation rates;

[0047] The expression of furnace pressure decay rate is:

[0048]

[0049] In the formula, SJ lyi is the furnace pressure decay rate of the i-th acquisition period, SC sd The duration corresponding to the collection period.

[0050] Furthermore, the method for obtaining the constancy of the single crystal diameter includes:

[0051] A1: Use a camera to capture single crystal pulling images at the start of i acquisition periods to obtain i starting pulling images;

[0052] A2: Mark the pixels in the image where the lifting starts, one by one, and record the pixel value of each pixel;

[0053] A3: Pixels with pixel values ​​greater than a preset pixel threshold are recorded as target pixels, and the area where the target pixels are located is recorded as a single crystal area;

[0054] A4: Draw lines along the vertical boundaries of the single crystal region to obtain two region lines, and mark m diameter points equidistantly on the two region lines;

[0055] A5: Measure the distance between two diameter points on the same horizontal line one by one to obtain m starting area diameters. Accumulate and average the m starting area diameters to obtain i first diameter values.

[0056] The expression for the first diameter value is:

[0057]

[0058] Where ZJ d1i is the first diameter value of the i-th acquisition period, ZJ skib is the diameter of the bth starting area in the i-th acquisition period;

[0059] A6: Use a camera to capture single crystal pulling images at the end of i acquisition periods, obtaining i end-of-pulling images;

[0060] A7: Mark the pixels in the image where the lifting is completed one by one and record the pixel value of each pixel;

[0061] A8: Repeat steps A3-A5 to obtain i second diameter values;

[0062] The expression for the second diameter value is:

[0063]

[0064] Where Zj d2i is the second diameter value of the i-th acquisition period, ZJ jsic is the diameter of the Cth ending area in the i-th acquisition period;

[0065] A9: Compare the i second diameter values ​​with the i first diameter values ​​in sequence to obtain the i single crystal diameter constancy;

[0066] The expression for the constancy of single crystal diameter is:

[0067]

[0068] Where ZJ hdi is the constant of the single crystal diameter in the i-th acquisition period.

[0069] Furthermore, the training method of the state prediction model for predicting the crystal state value in the next acquisition period includes:

[0070] The crystal state value includes normal crystal state and abnormal crystal state;

[0071] Pre-collect multiple sets of comprehensive operating parameters corresponding to the crystal furnace in normal crystal state and abnormal crystal state;

[0072] The comprehensive operating parameters are converted into multiple feature vectors using the sliding window method. The crystal state value is converted into a label corresponding to the comprehensive operating parameter according to the sliding step size. The normal crystal state is converted to 0, and the abnormal crystal state is converted to 1. One feature vector corresponds to one label and constitutes a set of training data. Multiple sets of training data constitute a training set. The comprehensive operating parameters are arranged in the order of acquisition time. The prediction time step Z, sliding step Q and sliding window length N are preset.

[0073] The characteristic vector is used as the input of the state prediction model, and the crystal state value of the next acquisition period after the predicted time step Z is used as the output. The subsequent crystal state value of each training set is used as the prediction target. The state prediction model is trained with the sum of the minimized prediction errors as the training goal to generate a state prediction model that predicts the crystal state value of the next acquisition period based on the comprehensive operating parameters of the previous acquisition period;

[0074] When the output of the state prediction model is 0, the crystal state value in the next acquisition period is the normal crystal state;

[0075] When the output of the state prediction model is 1, the crystal state value in the next acquisition period is an abnormal crystal state;

[0076] The methods for determining whether to issue a control prompt include:

[0077] When the crystal state value in the next acquisition period is a normal crystal state, it is determined that no control prompt will be issued;

[0078] When the crystal state value in the next acquisition period is an abnormal crystal state, it is determined that a control prompt is issued.

[0079] Furthermore, the identification method of the control target data includes:

[0080] Comparing the local temperature increment value with a preset temperature increment threshold value, and marking the local temperature increment value as control target data when the local temperature increment value is greater than the preset temperature increment threshold value;

[0081] Comparing the furnace pressure decay rate with a preset furnace pressure decay threshold, and when the furnace pressure decay rate is greater than the preset furnace pressure decay threshold, marking the furnace pressure decay rate as control target data;

[0082] The single crystal diameter constancy is compared with a preset diameter constancy threshold value, and when the single crystal diameter constancy is less than the preset diameter constancy threshold value, the single crystal diameter constancy is marked as control target data.

[0083] Furthermore, the method for formulating the instruction for reducing the local temperature increment value, the instruction for reducing the furnace pressure decay rate, and the instruction for increasing the single crystal diameter constancy includes:

[0084] When the control target data is the local temperature increment value, an instruction to reduce the local temperature increment value is formulated;

[0085] When the control target data is the furnace pressure decay rate, an instruction to reduce the furnace pressure decay rate is formulated;

[0086] When the control target data is the single crystal diameter constancy, an instruction to increase the single crystal diameter constancy is formulated.

[0087] Furthermore, the execution priority is: the priority of the instruction to reduce the local temperature increment value is higher than the priority of the instruction to reduce the furnace pressure decay rate, and the priority of the instruction to reduce the furnace pressure decay rate is higher than the priority of the instruction to increase the single crystal diameter constancy;

[0088] The control method for the crystal furnace to execute the optimization control instruction includes:

[0089] Count the number of control target data and obtain the control value;

[0090] When the control value is 1, the control terminal controls the crystal furnace to execute the instruction to reduce the local temperature increment value, the instruction to reduce the furnace pressure attenuation rate, or the instruction to increase the single crystal diameter constancy, until no control prompt is issued;

[0091] When the control value is 2, if the control target data are the local temperature increment and the furnace pressure decay rate, the control terminal first controls the crystal furnace to execute the instruction to reduce the local temperature increment. When the local temperature increment decreases to the preset temperature increment threshold, the control terminal then executes the instruction to reduce the furnace pressure decay rate until no control prompt is issued.

[0092] If the control target data is the local temperature increment and the single crystal diameter constancy, the control terminal first controls the crystal furnace to execute the instruction to reduce the local temperature increment. When the local temperature increment is reduced to the preset temperature increment threshold, the control terminal then executes the instruction to increase the single crystal diameter constancy until no control prompt is issued;

[0093] If the control target data is the furnace pressure decay rate and the single crystal diameter constancy, the control terminal first controls the crystal furnace to execute the instruction to reduce the furnace pressure decay rate. When the furnace pressure decay rate decreases to the preset furnace pressure decay threshold, the control terminal then executes the instruction to increase the single crystal diameter constancy until no control prompt is issued;

[0094] When the control value is 3, the control terminal controls the crystal furnace to synchronously execute the instructions of reducing the local temperature increment value, reducing the furnace pressure attenuation rate and increasing the single crystal diameter constancy, until it stops when no control prompt is issued.

[0095] The technical effects and advantages of the control method of a crystal furnace of the present invention are as follows:

[0096] The present invention obtains the basic operating parameters of the crystal furnace and determines whether the crystal furnace meets the operation and maintenance control requirements based on the safe operation and maintenance criteria, divides the acquisition period from the acquisition cycle, and acquires the comprehensive operating parameters of the crystal furnace in the acquisition period, inputs the acquired comprehensive operating parameters into a state prediction model that has been trained in advance to predict the crystal state value of the next acquisition period, predicts the crystal state value of the next acquisition period, and determines whether to issue a control prompt, identifies the control target data from the comprehensive operating parameters, and formulates the corresponding optimized control instructions, counts the number of control target data, and combines the execution priority to control the crystal furnace to execute the optimized control instructions until no control prompt is issued; compared with the prior art, through the preliminary judgment of the basic operating parameters, the prerequisite for crystal furnace state analysis and control can be improved, and the crystal furnace can be avoided. The additional workload caused by the large number of low-value parameters during the initial operation of the body furnace participating in the subsequent control analysis and calculation, combined with the comprehensive operating parameters and state prediction model, can accurately and in advance predict the crystal state value of the next acquisition period based on the crystal furnace operation data of the previous acquisition period, so that the low-quality phenomenon of the single crystal material that is about to appear can be predicted in advance, and the control target data that has a negative impact on the operation state of the crystal furnace can be accurately identified. At the same time, combined with the execution priority, the control instructions corresponding to the control target data are formulated and executed, so that the crystal furnace can implement optimized control measures before the low-quality crystal phenomenon occurs, avoiding the phenomenon of low-quality single crystal materials, thereby effectively avoiding the control lag problem caused by the real-time analysis and prediction method of real-time data acquisition, and greatly improving the control effect of the crystal furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0097] Figure 1 A schematic flow chart of a method for controlling a crystal furnace provided in Example 1 of the present invention;

[0098] Figure 2 A module schematic diagram of a crystal furnace control system provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0099] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0100] Example 1: Please refer to Figure 1 As shown, the control method of a crystal furnace described in this embodiment is applied to a control terminal, including:

[0101] S1: Obtain the basic operating parameters of the crystal furnace and determine whether the crystal furnace meets the operation and maintenance control requirements based on the safety operation and maintenance criteria;

[0102] Basic operating parameters refer to parameters that can be used to initialize the current operating status of the crystal furnace and serve as the basis for analyzing whether the operating status of the crystal furnace needs to be optimized and controlled in the future. They can also directly and clearly reflect the current initial status of the crystal furnace.

[0103] Basic operating parameters include furnace temperature and pressure values;

[0104] The furnace temperature value refers to the working temperature inside the crucible of the crystal furnace, which is used to melt the fluid of the polycrystalline material and grow single crystals. If the crystal furnace needs to be optimized and controlled later, the working temperature of the crucible must reach the lower limit of the temperature to ensure that the working temperature of the crystal furnace can meet the minimum temperature requirement for single crystal growth. The furnace temperature value is detected by the temperature sensor.

[0105] The pressure value inside the furnace refers to the working pressure of the fluid used to melt the polycrystalline material and grow single crystals in the crystal furnace. If the crystal furnace needs to be subsequently optimized and controlled, the working pressure inside the crystal furnace needs to reach the lower pressure limit to ensure that the working pressure inside the crystal furnace can meet the minimum pressure requirement for single crystal growth; the pressure value inside the furnace is obtained through detection by the air pressure sensor.

[0106] The safe operation and maintenance criteria are used to compare whether the crystal furnace can meet the operation and maintenance control requirements. They can judge the size of the furnace temperature and pressure values. When the furnace temperature and pressure values ​​both meet the safe operation and maintenance criteria, it indicates that the crystal furnace can meet the operation and maintenance control requirements, and subsequent optimization control processing can be carried out.

[0107] The safe operation and maintenance criteria are: there are no unqualified parameters in the basic operating parameters;

[0108] Methods for determining whether operation and maintenance control requirements are met include:

[0109] Compare the temperature value inside the furnace with the lower temperature limit; the lower temperature limit refers to the minimum temperature value at which the operating temperature inside the crystal furnace can reach and have a negative impact on the operating status of the crystal furnace, so that a large amount of data corresponding to low temperatures can be eliminated; the lower temperature limit is obtained by querying the minimum safe operating temperature value in the technical parameter table corresponding to the crystal furnace;

[0110] When the temperature value inside the furnace is less than the lower limit of the temperature, the temperature value inside the furnace is marked as an unqualified parameter;

[0111] Compare the pressure value in the furnace with the lower pressure limit; the lower pressure limit refers to the minimum pressure value at which the working pressure in the crystal furnace can reach a negative impact on the operation state of the crystal furnace, so that a large amount of data corresponding to low pressure can be eliminated; the lower pressure limit is obtained by querying the minimum safe operating pressure value in the technical parameter table corresponding to the crystal furnace;

[0112] When the pressure value in the furnace is less than the lower pressure limit, the pressure value in the furnace is marked as an unqualified parameter;

[0113] Count the number of unqualified parameters. When the number of unqualified parameters is 0, it means that the furnace temperature and pressure values ​​both meet the corresponding lower limits. There are no unqualified parameters, and it is determined that the operation and maintenance control requirements are met.

[0114] When the number of unqualified parameters is not 0, it means that there are furnace temperature values ​​and furnace pressure values ​​that do not meet the corresponding lower limit values, then there are unqualified parameters, and it is determined that the operation and maintenance control requirements are not met.

[0115] S2: dividing the collection period into collection periods from the collection cycle, and collecting the comprehensive operating parameters of the crystal furnace in the collection period;

[0116] The acquisition cycle refers to the time between the moment when the crystal furnace is determined to meet the operation control requirements and the current moment. It can limit the duration of data acquisition and status analysis of the crystal furnace and serve as the overall corresponding duration for subsequent acquisition periods. It can also affect the corresponding duration of a single acquisition period. The acquisition period is the minimum acquisition duration corresponding to changes in the operating data in the crystal furnace, ensuring that the amount of data in each acquisition period can meet the acquisition and calculation requirements.

[0117] The methods for dividing the collection period include:

[0118] Use the timestamp to query the time when the crystal furnace first meets the operation and maintenance control requirements, and record it as the cycle start time;

[0119] The period between the start time of the cycle and the current time is recorded as the collection period;

[0120] The collection cycle is divided into i consecutive collection periods based on the preset unit duration, and the start and end times of each i collection period are marked. The preset unit duration is the minimum value corresponding to the collection period when the collection cycle is divided into periods. This ensures that each collection period remains the same length after division, and also ensures that the divided collection period can accommodate sufficient data that has changed and provide it for subsequent collection and calculation. The preset unit duration is obtained by collecting a large number of historical minimum durations that can accommodate sufficient data that has changed, and then calculating their average value.

[0121] It should be noted that since the collection cycle is a continuous period of time, each collection period is also a continuous period of time, and there will be no time discontinuity. The start time and end time serve as the starting point and end point of the collection period, which are used to close the collection period and improve the independence of each collection period. Therefore, the end time of the previous collection period and the start time of the next collection period are the same time on the timeline.

[0122] Comprehensive operating parameters refer to the diverse data generated by the crystal furnace during the acquisition period that can affect the operating status of the crystal furnace and lead to the quality of subsequent single crystal growth, thus providing a comprehensive representation of the real-time parameters within the crystal furnace;

[0123] Comprehensive operating parameters include local temperature increment, furnace pressure decay rate and single crystal diameter constancy;

[0124] The local temperature increment refers to the magnitude of the temperature difference between the polycrystalline material fluid in the crucible and the inner wall of the crucible above the polycrystalline material fluid in the crystal furnace. When the local temperature increment is larger, it means that the magnitude of the temperature difference between the polycrystalline material fluid in the crucible and the inner wall of the crucible above the polycrystalline material fluid is larger, and the temperature difference between the inner wall of the crucible and the polycrystalline material fluid will gradually increase, and the operating state of the crystal furnace will be worse at this time.

[0125] Methods for obtaining the local temperature increment include:

[0126] Randomly mark p discontinuous moments in i acquisition periods to obtain p detection moments;

[0127] At p detection moments, a thermal infrared camera is used to capture real-time images of the interior of the crucible in the crystal furnace, obtaining p thermal infrared images;

[0128] Using computer vision technology, the position of the liquid surface of the polycrystalline material fluid and the position of the upper edge of the crucible in the thermal infrared image are identified to obtain a first boundary and a second boundary respectively;

[0129] Measure the distance between the first boundary and the second boundary using a scale to obtain the remaining height value of the inner wall;

[0130] Take the remaining height of one-third of the inner wall as a unit length, take the first dividing line as the base point, and move vertically upward by a distance corresponding to the unit length to obtain the third boundary;

[0131] The area between the third boundary and the second boundary in the thermal infrared image is recorded as the inner wall area, and the area below the first boundary in the thermal infrared image is recorded as the fluid area;

[0132] Sequentially record the minimum temperature value of the inner wall area at p detection moments and the maximum temperature value of the fluid area at p detection moments to obtain p inner wall temperature values ​​and p fluid temperature values;

[0133] After subtracting the p inner wall temperature values ​​from the corresponding p fluid temperature values, p sub-incremental values ​​are obtained;

[0134] The expression for the sub-increment value is:

[0135] DZ zip =WD lip -WD nip ;

[0136] Where DZ zip is the pth sub-increment value in the i-th acquisition period, WD lip is the pth fluid temperature value in the ith acquisition period, WD nip is the pth inner wall temperature value in the i-th acquisition period;

[0137] Accumulate the p sub-incremental values ​​and average them to obtain i local temperature increment values;

[0138] The expression of the local temperature increment is:

[0139]

[0140] Where DZ jyi is the local temperature increment during the i-th acquisition period, DZ zia is the ath sub-increment value in the i-th acquisition period.

[0141] The furnace pressure decay rate refers to the rate at which the pressure in the crystal furnace decreases due to the leakage of the protective gas in the crystal furnace. When the furnace pressure decay rate is larger, it means that the rate at which the pressure in the crystal furnace decreases due to the leakage of the protective gas in the crystal furnace is larger, and the crystallization pressure in the crystal furnace will gradually decrease. At this time, the operating state of the crystal furnace is worse.

[0142] Methods for obtaining furnace pressure decay rate include:

[0143] The pressure sensor is used to detect the furnace pressure corresponding to the start and end times of i acquisition periods, and obtain i starting furnace pressure values ​​and i ending furnace pressure values;

[0144] After subtracting the i starting furnace pressure values ​​from the i ending furnace pressure values ​​one by one, i attenuation values ​​are obtained;

[0145] The expression of the attenuation value is:

[0146] SJ zi =LY ksi -LY jsi ;

[0147] In the formula, SJ zi is the attenuation value of the i-th acquisition period, LY ksi is the starting furnace pressure value of the i-th collection period, LY jsi is the ending furnace pressure value of the i-th collection period;

[0148] Compare the i attenuation values ​​with the duration corresponding to the acquisition period in turn to obtain i furnace pressure attenuation rates;

[0149] The expression of furnace pressure decay rate is:

[0150]

[0151] In the formula, SJ lyi is the furnace pressure decay rate of the i-th acquisition period, SC sd The duration corresponding to the collection period.

[0152] The single crystal diameter constancy refers to the area where the diameter of the single crystal rod grown from the crucible in the crystal furnace remains consistent. The greater the single crystal diameter constancy, the greater the area where the diameter of the single crystal rod grown from the crucible remains consistent, the higher the quality of the single crystal rod grown from the crucible, and the better the operation status of the crystal furnace.

[0153] Methods for obtaining the constancy of single crystal diameter include:

[0154] A1: Use a camera to capture single crystal pulling images at the start of i acquisition periods to obtain i starting pulling images;

[0155] A2: Mark the pixels in the image where the lifting starts, one by one, and record the pixel value of each pixel;

[0156] A3: Pixels with values ​​greater than a preset pixel threshold are recorded as target pixels, and the area where the target pixels are located is recorded as a single crystal area. The preset pixel threshold is the critical value between the pixel values ​​in the area where the single crystal rod is located and the pixel values ​​in the area where the non-single crystal rod is located. This can be used to distinguish the pixel values ​​of the target pixels, thereby improving the recognition accuracy of the target pixels. The preset pixel threshold is obtained by collecting the minimum pixel values ​​corresponding to a large number of target pixels in history and calculating their average value.

[0157] A4: Draw lines along the vertical boundaries of the single crystal region to obtain two region lines, and mark m diameter points equidistantly on each of the two region lines. The diameter points are used to determine the distance between the two boundaries of the single crystal region in the starting pulling image, thereby reflecting the positions of the two end points of the connecting line where the diameter of the single crystal rod is located.

[0158] A5: Measure the distance between two diameter points on the same horizontal line one by one to obtain m starting area diameters. Accumulate and average the m starting area diameters to obtain i first diameter values.

[0159] The expression for the first diameter value is:

[0160]

[0161] Where ZJ d1i is the first diameter value of the i-th acquisition period, ZJ ksib is the diameter of the bth starting area in the i-th acquisition period;

[0162] A6: Use a camera to capture single crystal pulling images at the end of i acquisition periods, obtaining i end-of-pulling images;

[0163] A7: Mark the pixels in the image where the lifting is completed one by one and record the pixel value of each pixel;

[0164] A8: Repeat steps A3-A5 to obtain i second diameter values;

[0165] The expression for the second diameter value is:

[0166]

[0167] Where ZJ d2i is the second diameter value of the i-th acquisition period, ZJ jsic is the diameter of the cth ending area in the ith acquisition period;

[0168] A9: Compare the i second diameter values ​​with the i first diameter values ​​in sequence to obtain the i single crystal diameter constancy;

[0169] The expression for the constancy of single crystal diameter is:

[0170]

[0171] Where ZJ hdi is the constant of the single crystal diameter in the i-th acquisition period.

[0172] S3: Input the collected comprehensive operating parameters into a state prediction model that has been trained in advance to predict the crystal state value in the next collection period, predict the crystal state value in the next collection period, and determine whether to issue a control prompt;

[0173] After obtaining the real-time comprehensive operating parameters, the comprehensive operating parameters can be input into a state prediction model that has been trained in advance and can predict the crystal state value of the next acquisition period, thereby predicting the crystal state value of the next acquisition period corresponding to the comprehensive operating parameters of the current period;

[0174] The crystal state value is used to indicate the quality of the single crystal rod grown in the crystal furnace, so as to directly indicate the current operating state of the crystal furnace. The crystal state value includes normal crystal state and abnormal crystal state. Normal crystal state indicates that the quality of the grown single crystal rod is high and the operating state of the crystal furnace is good. Abnormal crystal state indicates that the quality of the grown single crystal rod is low and the operating state of the crystal furnace is poor.

[0175] The training method of the state prediction model for predicting the crystal state value in the next acquisition period includes:

[0176] Pre-collect multiple sets of comprehensive operating parameters corresponding to the crystal furnace in normal crystal state and abnormal crystal state;

[0177] The comprehensive operating parameters are converted into multiple feature vectors using a sliding window method, and the crystal state value is converted into a label corresponding to the comprehensive operating parameters according to the sliding step. For example, the normal crystal state is converted into 0, and the abnormal crystal state is converted into 1. One feature vector corresponds to one label, and constitutes a group of training data. Multiple groups of training data constitute a training set. The comprehensive operating parameters are arranged in order of acquisition time, and the prediction time step Z, sliding step Q and sliding window length N are preset; the feature vector is used as the input of the state prediction model, and the crystal state value of the next acquisition period after the prediction time step Z is used as the output. The subsequent crystal state value of each training set is used as the prediction target. The state prediction model is trained with the minimized sum of prediction errors as the training target to generate a state prediction model that predicts the crystal state value of the next acquisition period according to the comprehensive operating parameters of the previous acquisition period;

[0178] Exemplarily, the state prediction model is any one of a CNN neural network model or AlexNet;

[0179] The calculation formula for the prediction error is:

[0180] zk=(ak-wk) 2 ;

[0181] Where zk is the prediction error, k is the group number of the feature vector; ak is the predicted state value corresponding to the k-th group of feature vectors, and wk is the actual state value corresponding to the k-th group of training data;

[0182] In the state prediction model, the eigenvector is the comprehensive operating parameter, and the state value is the crystal state value;

[0183] Other model parameters of the state prediction model, including target loss value, optimization algorithm, training set, test set, and validation set ratio, as well as optimization of the loss function, are all obtained through actual engineering implementation and continuous experimental tuning.

[0184] When the output of the state prediction model is 0, the crystal state value in the next acquisition period is the normal crystal state;

[0185] When the output of the state prediction model is 1, the crystal state value in the next acquisition period is an abnormal crystal state;

[0186] When the state prediction model outputs different crystal state values, it indicates that the operating state of the crystal furnace in the next acquisition period will be different, and it is necessary to determine whether to perform data recognition and analysis in the next acquisition period of the crystal furnace;

[0187] The methods for determining whether to issue a control prompt include:

[0188] When the crystal status value in the next acquisition period is a normal crystal status, it means that there is no abnormality in the operation status of the crystal furnace, and it is determined that no control prompt will be issued;

[0189] When the crystal state value in the next acquisition period is an abnormal crystal state, it indicates that the operation state of the crystal furnace is abnormal, and a control prompt is issued.

[0190] S4: Identify control target data from the comprehensive operating parameters and formulate corresponding optimization control instructions; the optimization control instructions include instructions for reducing the local temperature increment value, reducing the furnace pressure decay rate, and increasing the single crystal diameter constancy;

[0191] When it is determined that a control prompt is issued, it indicates that there is an abnormality in the operating state of the crystal furnace. It is necessary to identify the abnormal data from the local temperature increment value, furnace pressure decay rate and single crystal diameter constancy that affect the crystal state value, and mark the abnormal data as control target data, so that the control target data can be used as a data object for subsequent optimization control of the operating state of the crystal furnace;

[0192] Methods for identifying control target data include:

[0193] The local temperature increment value is compared with a preset temperature increment threshold value; the preset temperature increment threshold value refers to the maximum value of the local temperature increment value in the previous acquisition period when the crystal state value of the crystal furnace in the next acquisition period is in a normal crystal state, which can limit the maximum value of the local temperature increment value in the previous acquisition period; the preset temperature increment threshold value is obtained by collecting a large number of historical crystal furnaces in the next acquisition period, the maximum values ​​of which in the previous acquisition period when the crystal state value is in a normal crystal state, and then calculating the average value;

[0194] When the local temperature increment value is greater than the preset temperature increment threshold, it means that the local temperature increment value exceeds the maximum value of the local temperature increment value in the previous acquisition period when the crystal state value of the crystal furnace in the next acquisition period is the normal crystal state, and the local temperature increment value is marked as the control target data;

[0195] The furnace pressure decay rate is compared with a preset furnace pressure decay threshold value; the preset furnace pressure decay threshold value refers to the maximum value of the furnace pressure decay threshold rate of the previous acquisition period when the crystal state value of the crystal furnace in the next acquisition period is a normal crystal state, and the maximum value of the furnace pressure decay threshold rate of the previous acquisition period can be limited; the preset furnace pressure decay threshold value is obtained by collecting a large number of historical crystal furnaces in the next acquisition period, and calculating the average value of the furnace pressure decay rate of the previous acquisition period when the crystal state value of the crystal furnace in the next acquisition period is a normal crystal state;

[0196] When the furnace pressure decay rate is greater than the preset furnace pressure decay threshold, it means that the furnace pressure decay rate exceeds the maximum value of the furnace pressure decay rate of the previous acquisition period when the crystal state value of the crystal furnace in the next acquisition period is the normal crystal state, and the furnace pressure decay rate is marked as the control target data;

[0197] The single crystal diameter constancy is compared with a preset diameter constancy threshold value; the preset diameter constancy threshold value refers to the minimum value of the single crystal diameter constancy in the previous acquisition period when the crystal state value in the next acquisition period of the crystal furnace is in a normal crystal state, so that the minimum value of the single crystal diameter constancy in the previous acquisition period can be limited; the preset diameter constancy threshold value is obtained by collecting a large number of historical minimum values ​​of the single crystal diameter constancy in the previous acquisition period when the crystal state value in the next acquisition period of the crystal furnace is in a normal crystal state, and calculating the average value thereof;

[0198] When the single crystal diameter constancy is less than the preset diameter constancy threshold, it means that the single crystal diameter constancy exceeds the minimum value of the single crystal diameter constancy in the previous acquisition period when the crystal state value of the next acquisition period of the crystal furnace is the normal crystal state, and the single crystal diameter constancy is marked as the control target data.

[0199] The optimization control instruction is an instruction for optimizing the control of the crystal furnace according to the amount of control target data, and can perform different optimization control measures on the crystal furnace;

[0200] The optimization control instructions include instructions for reducing the local temperature increment value, reducing the furnace pressure decay rate, and increasing the single crystal diameter constancy;

[0201] The method for formulating the instruction for reducing the local temperature increment value, the instruction for reducing the furnace pressure decay rate, and the instruction for increasing the single crystal diameter constancy includes:

[0202] When the control target data is the local temperature increment value, it means that the local temperature increment value will cause the single crystal state value to be abnormal. At this time, an instruction to reduce the local temperature increment value is formulated;

[0203] When the control target data is the furnace pressure decay rate, it means that the furnace pressure decay rate will cause the single crystal state value to be abnormal. At this time, an instruction to reduce the furnace pressure decay rate is formulated;

[0204] When the control target data is the single crystal diameter constancy, it means that the single crystal diameter constancy will cause the single crystal state value to be abnormal. At this time, an instruction to increase the single crystal diameter constancy is formulated.

[0205] S5: Count the number of control target data and, combined with the execution priority, control the crystal furnace to execute the optimized control instructions until no control prompt is issued;

[0206] The execution priority is used to determine the specific execution order of the comprehensive operating parameters identified as the control target data. This can be used to calibrate the execution order of different comprehensive operating parameters so that the control target data can be executed one by one and in an orderly manner, thereby improving the operation state of the crystal furnace and avoiding the phenomenon of low-quality single crystal rods being grown.

[0207] When single crystal ingots are grown and manufactured in a crystal furnace, the temperature directly affects the quality of the growth and pulling of the single crystal ingots, and has the greatest impact on the quality of the growth and pulling of the single crystal ingots. Therefore, the instruction to reduce the local temperature increment has the highest priority. The furnace pressure also affects the quality of the growth and pulling of the single crystal ingots, but its impact is smaller than that caused by the temperature. The diameter of the single crystal ingot can only be used to judge the quality of the single crystal from the external diameter of the single crystal, and its impact is the smallest.

[0208] Therefore, the execution priority is: the priority of the instruction to reduce the local temperature increment is higher than the priority of the instruction to reduce the furnace pressure attenuation rate, and the priority of the instruction to reduce the furnace pressure attenuation rate is higher than the priority of the instruction to increase the single crystal diameter constancy.

[0209] The control method for the crystal furnace to execute the optimization control instruction includes:

[0210] Count the number of control target data and obtain the control value;

[0211] When the control value is 1, it means that the number of control target data is 1. At this time, there is no need to perform orderly execution according to the execution priority. The control terminal controls the crystal furnace to execute the instruction of reducing the local temperature increment value, reducing the furnace pressure attenuation rate, or increasing the single crystal diameter constancy corresponding to the control target data until no control prompt is issued;

[0212] When the control value is 2, it means that the number of control target data is 2, and in this case, orderly execution is required according to the execution priority;

[0213] If the control target data is the local temperature increment value and the furnace pressure attenuation rate, the control terminal first controls the crystal furnace to execute the instruction to reduce the local temperature increment value. When the local temperature increment value is reduced to the preset temperature increment threshold, the instruction to reduce the furnace pressure attenuation rate is then executed until no control prompt is issued;

[0214] If the control target data is the local temperature increment and the single crystal diameter constancy, the control terminal first controls the crystal furnace to execute the instruction to reduce the local temperature increment. When the local temperature increment is reduced to the preset temperature increment threshold, the control terminal then executes the instruction to increase the single crystal diameter constancy until no control prompt is issued;

[0215] If the control target data is the furnace pressure decay rate and the single crystal diameter constancy, the control terminal first controls the crystal furnace to execute the instruction to reduce the furnace pressure decay rate. When the furnace pressure decay rate decreases to the preset furnace pressure decay threshold, the control terminal then executes the instruction to increase the single crystal diameter constancy, and stops when no control prompt is issued.

[0216] When the control value is 3, it means that the number of control target data is 3. At this time, there is no need to execute the corresponding optimization control instructions according to the execution priority. The control terminal controls the crystal furnace to synchronously execute the instructions to reduce the local temperature increment value, reduce the furnace pressure attenuation rate and increase the single crystal diameter constancy until no control prompt is issued.

[0217] In this embodiment, by obtaining the basic operating parameters of the crystal furnace and based on the safe operation and maintenance criteria, it is determined whether the crystal furnace meets the operation and maintenance control requirements, the acquisition period is divided from the acquisition cycle, and the comprehensive operating parameters of the crystal furnace in the acquisition period are collected, and the collected comprehensive operating parameters are input into a state prediction model that has been trained in advance to predict the crystal state value of the next acquisition period, the crystal state value of the next acquisition period is predicted, and it is determined whether to issue a control prompt, the control target data is identified from the comprehensive operating parameters, and the corresponding optimization control instructions are formulated, the number of control target data is counted, and combined with the execution priority, the crystal furnace is controlled to execute the optimization control instructions until no control prompt is issued; compared with the existing technology, the prerequisite for crystal furnace state analysis and control can be improved through preliminary judgment of the basic operating parameters, avoiding It reduces the extra workload caused by a large number of low-value parameters during the initial operation of the crystal furnace participating in the subsequent control analysis and calculation. At the same time, combined with the comprehensive operating parameters and state prediction model, it can accurately and in advance predict the crystal state value of the next acquisition period based on the crystal furnace operation data of the previous acquisition period, so that the low-quality phenomenon of the single crystal material that is about to appear can be predicted in advance, and the control target data that has a negative impact on the operation state of the crystal furnace can be accurately identified. At the same time, combined with the execution priority, the control instructions corresponding to the control target data are formulated and executed, so that the crystal furnace can implement optimized control measures before the low-quality crystal phenomenon occurs, avoiding the phenomenon of low-quality single crystal materials, thereby effectively avoiding the problem of control lag caused by the real-time analysis and prediction method of real-time data acquisition, and greatly improving the control effect of the crystal furnace.

[0218] Example 2: Please refer to Figure 2 As shown, for the parts not described in detail in this embodiment, please refer to the description of Example 1. A control system for a crystal furnace is provided, which is applied to a control terminal and is used to implement a control method for a crystal furnace, including a demand determination module, a data acquisition module, a model prediction module, an instruction formulation module and an instruction execution module, wherein the modules are connected via a wired or wireless network;

[0219] The demand determination module is used to obtain the basic operating parameters of the crystal furnace and determine whether the crystal furnace meets the operation and maintenance control requirements based on the safety operation and maintenance criteria;

[0220] The data acquisition module is used to divide the acquisition period from the acquisition cycle and collect the comprehensive operating parameters of the crystal furnace during the acquisition period;

[0221] The model prediction module is used to input the collected comprehensive operating parameters into a state prediction model that has been trained in advance to predict the crystal state value in the next collection period, predict the crystal state value in the next collection period, and determine whether to issue a control prompt;

[0222] The instruction formulation module is used to identify the control target data from the comprehensive operating parameters and formulate the corresponding optimized control instructions;

[0223] The instruction execution module is used to count the number of control target data and, in combination with the execution priority, control the crystal furnace to execute the optimized control instructions until no control prompt is issued.

[0224] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be covered by the scope of protection of the present invention.

Claims

1. A crystal furnace control method, applied to a control terminal, characterized in that: include: S1: Obtain the basic operating parameters of the crystal furnace and determine whether the crystal furnace meets the operation and maintenance control requirements based on the safe operation and maintenance criteria; if it meets the operation and maintenance control requirements, execute S2; if it does not meet the operation and maintenance control requirements, repeat S1; S2: dividing the acquisition period into acquisition periods from the acquisition cycle, and acquiring comprehensive operating parameters of the crystal furnace during the acquisition period, the comprehensive operating parameters including the local temperature increment, the furnace pressure decay rate, and the single crystal diameter constancy; Methods for obtaining the constancy of single crystal diameter include: A1: Shoot separately through the camera The single crystal pulling image at the beginning of the acquisition period is obtained Start lifting the image; A2: Mark the pixels in the image where the lifting starts, one by one, and record the pixel value of each pixel; A3: Pixels with pixel values ​​greater than a preset pixel threshold are recorded as target pixels, and the area where the target pixels are located is recorded as a single crystal area; A4: Draw lines along the vertical boundaries of the single crystal region to obtain two region lines, and mark the two region lines at equal distances. diameter points; A5: Measure the distance between two diameter points on the same horizontal line one by one to obtain The diameter of the starting area, The diameters of the starting areas are accumulated and averaged to obtain First diameter value; A6: Shoot separately through the camera The single crystal pulling image at the end of the acquisition period is obtained End lifting image; A7: Mark the pixels in the image where the lifting is completed one by one and record the pixel value of each pixel; A8: Repeat steps A3-A5 to obtain Second diameter value; A9: The second diameter values ​​are Compare the first diameter values ​​and obtain The constancy of the single crystal diameter; S3: Input the collected comprehensive operating parameters into a state prediction model that has been trained in advance to predict the crystal state value in the next collection period, predict the crystal state value in the next collection period, and determine whether to issue a control prompt; if not, repeat S3; if so, execute S4-S5; The crystal state value includes normal crystal state and abnormal crystal state; The methods for determining whether to issue a control prompt include: When the crystal state value in the next acquisition period is a normal crystal state, it is determined that no control prompt will be issued; When the crystal state value in the next acquisition period is an abnormal crystal state, a control prompt is issued; S4: Identify control target data from the comprehensive operating parameters and formulate corresponding optimization control instructions, which include instructions for reducing the local temperature increment value, reducing the furnace pressure decay rate, and increasing the single crystal diameter constancy; S5: Count the number of control target data, and control the crystal furnace to execute the optimized control instructions in combination with the execution priority until no control prompt is issued.

2. The crystal furnace control method according to claim 1, characterized in that: The basic operating parameters include the furnace temperature value and the furnace pressure value; The safe operation and maintenance criteria are: there are no unqualified parameters in the basic operating parameters; Methods for determining whether operation and maintenance control requirements are met include: Compare the furnace temperature value with the lower temperature limit. When the furnace temperature value is less than the lower temperature limit, mark the furnace temperature value as an unqualified parameter. Compare the furnace pressure value with the pressure lower limit value, and when the furnace pressure value is less than the pressure lower limit value, mark the furnace pressure value as an unqualified parameter; Count the number of unqualified parameters. When the number of unqualified parameters reaches 0, it is determined that the operation and maintenance control requirements are met. When the number of unqualified parameters is not 0, it is determined that the operation and maintenance control requirements are not met.

3. The crystal furnace control method according to claim 2, characterized in that: The method for dividing the collection time period includes: Use the timestamp to query the time when the crystal furnace first meets the operation and maintenance control requirements, and record it as the cycle start time; The period between the start time of the cycle and the current time is recorded as the collection period; Based on the preset unit time, the collection period is divided into Continuous collection periods are marked The start and end times of each collection period.

4. The method for controlling a crystal furnace according to claim 3, wherein: The method for obtaining the local temperature increment value includes: exist Randomly mark out discrete moments, obtain Detection moment; exist At each detection moment, a real-time image of the crucible inside the crystal furnace is captured by a thermal infrared camera to obtain Thermal infrared images; Using computer vision technology, the position of the liquid surface of the polycrystalline material fluid and the position of the upper edge of the crucible in the thermal infrared image are identified to obtain a first boundary and a second boundary respectively; Measure the distance between the first boundary and the second boundary using a scale to obtain the remaining height value of the inner wall; Take the remaining height of one-third of the inner wall as a unit length, take the first dividing line as the base point, and move vertically upward by a distance corresponding to the unit length to obtain the third boundary; The area between the third boundary and the second boundary in the thermal infrared image is recorded as the inner wall area, and the area below the first boundary in the thermal infrared image is recorded as the fluid area; Record the inner wall area in sequence The minimum temperature and fluid area at each detection moment The maximum temperature at the detection moment is obtained The inner wall temperature and Fluid temperature value; Will The inner wall temperature value and the corresponding After subtracting the fluid temperature values, we can obtain The value of the child increases; The expression for the sub-increment value is: ； Where, For the The first The value of the child increases, For the The first The fluid temperature value, For the The first Inner wall temperature value; Will After accumulating the increment value of each child, we get the average value. A local temperature increment; The expression of the local temperature increment is: ； Where, For the The local temperature increment during each acquisition period is For the The first collection period The value of the child increases.

5. The method for controlling a crystal furnace according to claim 4, wherein: The method for obtaining the furnace pressure decay rate includes: Detected by air pressure sensor The furnace pressure corresponding to the start and end time of each collection period is obtained. The starting furnace pressure value and The final furnace pressure value; Will The starting furnace pressure value and After subtracting the end furnace pressure values ​​one by one, we can get attenuation value; The expression of the attenuation value is: ； Where, For the The attenuation value of each acquisition period, For the The starting furnace pressure value of each collection period, For the The ending furnace pressure value of each collection period; Will The attenuation values ​​are compared with the duration corresponding to the acquisition period in turn to obtain Furnace pressure decay rate; The expression of furnace pressure decay rate is: ； Where, For the The furnace pressure decay rate during each collection period, The duration corresponding to the collection period.

6. The method for controlling a crystal furnace according to claim 5, wherein: The expression of the first diameter value is: ； Where, For the The first diameter value of the acquisition period, For the The first The diameter of the starting area; The expression for the second diameter value is: ； Where, For the The second diameter value of the acquisition period, For the The first collection period The diameter of the end area; The expression for the constancy of single crystal diameter is: ； Where, For the The single crystal diameter constancy during each acquisition period.

7. The method for controlling a crystal furnace according to claim 6, wherein: The training method of the state prediction model for predicting the crystal state value in the next acquisition period includes: Pre-collect multiple sets of comprehensive operating parameters corresponding to the crystal furnace in normal crystal state and abnormal crystal state; The comprehensive operating parameters are converted into multiple feature vectors using the sliding window method. The crystal state value is converted into a label corresponding to the comprehensive operating parameter according to the sliding step size. The normal crystal state is converted to 0, and the abnormal crystal state is converted to 1. One feature vector corresponds to one label and constitutes a set of training data. Multiple sets of training data constitute a training set. The comprehensive operating parameters are arranged in the order of acquisition time. The prediction time step Z, sliding step Q and sliding window length N are preset. The characteristic vector is used as the input of the state prediction model, and the crystal state value of the next acquisition period after the predicted time step Z is used as the output. The subsequent crystal state value of each training set is used as the prediction target. The state prediction model is trained with the sum of the minimized prediction errors as the training goal to generate a state prediction model that predicts the crystal state value of the next acquisition period based on the comprehensive operating parameters of the previous acquisition period; When the output of the state prediction model is 0, the crystal state value in the next acquisition period is the normal crystal state; When the output of the state prediction model is 1, the crystal state value in the next acquisition period is an abnormal crystal state.

8. The method for controlling a crystal furnace according to claim 7, wherein: The control target data identification method includes: Comparing the local temperature increment value with a preset temperature increment threshold value, and marking the local temperature increment value as control target data when the local temperature increment value is greater than the preset temperature increment threshold value; Comparing the furnace pressure decay rate with a preset furnace pressure decay threshold, and when the furnace pressure decay rate is greater than the preset furnace pressure decay threshold, marking the furnace pressure decay rate as control target data; The single crystal diameter constancy is compared with a preset diameter constancy threshold value, and when the single crystal diameter constancy is less than the preset diameter constancy threshold value, the single crystal diameter constancy is marked as control target data.

9. The crystal furnace control method according to claim 8, characterized in that: The method for formulating the instruction for reducing the local temperature increment value, the instruction for reducing the furnace pressure decay rate, and the instruction for increasing the single crystal diameter constancy includes: When the control target data is the local temperature increment value, an instruction to reduce the local temperature increment value is formulated; When the control target data is the furnace pressure decay rate, an instruction to reduce the furnace pressure decay rate is formulated; When the control target data is the single crystal diameter constancy, an instruction to increase the single crystal diameter constancy is formulated.

10. The crystal furnace control method according to claim 9, characterized in that: The execution priority is: the priority of the instruction to reduce the local temperature increment value is higher than the priority of the instruction to reduce the furnace pressure decay rate, and the priority of the instruction to reduce the furnace pressure decay rate is higher than the priority of the instruction to increase the single crystal diameter constancy; The control method for the crystal furnace to execute the optimization control instruction includes: Count the number of control target data and obtain the control value; When the control value is 1, the control terminal controls the crystal furnace to execute the instruction to reduce the local temperature increment value, the instruction to reduce the furnace pressure attenuation rate, or the instruction to increase the single crystal diameter constancy, until no control prompt is issued; When the control value is 2, if the control target data are the local temperature increment and the furnace pressure decay rate, the control terminal first controls the crystal furnace to execute the instruction to reduce the local temperature increment. When the local temperature increment decreases to the preset temperature increment threshold, the control terminal then executes the instruction to reduce the furnace pressure decay rate until no control prompt is issued. If the control target data is the local temperature increment and the single crystal diameter constancy, the control terminal first controls the crystal furnace to execute the instruction to reduce the local temperature increment. When the local temperature increment is reduced to the preset temperature increment threshold, the control terminal then executes the instruction to increase the single crystal diameter constancy until no control prompt is issued; If the control target data is the furnace pressure decay rate and the single crystal diameter constancy, the control terminal first controls the crystal furnace to execute the instruction to reduce the furnace pressure decay rate. When the furnace pressure decay rate decreases to the preset furnace pressure decay threshold, the control terminal then executes the instruction to increase the single crystal diameter constancy until no control prompt is issued; When the control value is 3, the control terminal controls the crystal furnace to synchronously execute the instructions of reducing the local temperature increment value, reducing the furnace pressure attenuation rate and increasing the single crystal diameter constancy, until it stops when no control prompt is issued.

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