Crystal pulling temperature control method of single crystal furnace

Abstract

The invention relates to the technical field of crystal pulling, and provides a crystal pulling temperature control method of a single crystal furnace, which comprises the following steps: collecting a training data set in a temperature control process, and establishing a temperature control model; obtaining the solid-liquid ratio in the single crystal furnace for multiple times to obtain the average solid-liquid ratio in the single crystal furnace within a period of time and the fluctuation condition of the solid-liquid ratio along with time; the lifting of the guide cylinder is controlled based on the fluctuation condition of the solid-liquid proportion along with time; sending the average solid-liquid ratio to a temperature control model, thereby controlling to reduce the power of the bottom heater, turn off the bottom heater, turn on the bottom heater for the second time, reduce the power of the main heater and increase the power of the main heater; and after the power of the main heater is reduced, performing crucible position fixing operation, comparing the solid-to-liquid ratio in the furnace when the heater is adjusted with the average solid-to-liquid ratio within a period of time after the heater is adjusted, and judging whether the bottom heater is secondarily started and / or the power of the main heater is increased or not, so that the influence of insufficient heat in the furnace on subsequent material melting is avoided, and the liquid temperature after crucible position fixing is ensured to be within a standard range.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal pulling, and in particular to a crystal pulling temperature control method of a single crystal furnace. Background Art

[0002] As the most important semiconductor material, single crystal silicon is widely used in large-scale circuits, semiconductor devices and solar cells, and has a huge market demand.

[0003] During the operation of the single crystal furnace of the Czochralski method, new silicon materials need to be added after the crystal rod is taken out to ensure that the furnace can operate for a long time with high efficiency. However, after the material addition is completed, the production personnel need to operate according to the actual situation in the furnace to control the liquid surface temperature to reach the melting liquid temperature. The commonly used temperature control method requires personnel to pay attention to the size of the material block in the furnace at all times after the barrel is taken out, and adjust the heating power by visually detecting the change of the solid-liquid ratio and the maximum time limit from the last barrel of material to full melting or half melting.

[0004] However, due to the limited field of view in the furnace, if the material blocks float out of the field of view in the above method, the solid-liquid ratio will be inaccurate, the bottom heater will be shut down prematurely, thus affecting the subsequent material fusion, and ultimately the liquid temperature will not be within the standard range after the crucible is positioned. There is also a risk that the unmelted material blocks will float back after the crucible is automatically raised and stick to the guide tube, causing accidents. Summary of the invention

[0005] One of the purposes of the present application is to provide a crystal pulling temperature control method for a single crystal furnace to solve the problem that the above-mentioned material blocks float out of the field of view, resulting in inaccurate solid-liquid ratio, causing the bottom heater to be shut down prematurely, affecting subsequent material melting, and ultimately resulting in the liquid temperature being outside the standard range after the crucible is positioned. There is also a risk that the unmelted material blocks will float back and stick to the guide tube after the crucible is automatically raised, causing accidents.

[0006] To achieve the above objectives, this application adopts the following technical solutions:

[0007] A method for controlling the crystal pulling temperature of a single crystal furnace comprises the following steps:

[0008] Step S10, collecting a training data set in the temperature control process, and establishing a temperature control model based on the training data set; obtaining the solid-liquid ratio in the single crystal furnace for multiple times, and obtaining the average solid-liquid ratio in the single crystal furnace over a period of time and the fluctuation of the solid-liquid ratio over time;

[0009] Step S20, based on the fluctuation of the solid-liquid ratio over time, controlling the lifting and lowering of the guide tube; sending the average solid-liquid ratio to the temperature control model, and controlling the adjustment of the heater based on the output result of the temperature control model, wherein the adjustment of the heater includes reducing the power of the bottom heater, turning off the bottom heater, turning on the bottom heater twice, reducing the power of the main heater, and increasing the power of the main heater;

[0010] Step S30, obtaining the solid-liquid ratio in the single crystal furnace when the bottom heater is turned off and the average solid-liquid ratio in the single crystal furnace within a period of time after the bottom heater is turned off, and determining whether to turn on the bottom heater again;

[0011] Step S40, after reducing the power of the main heater, perform the crucible positioning operation; and obtain the solid-liquid ratio in the single crystal furnace when the power of the main heater is reduced and the average solid-liquid ratio in the single crystal furnace for a period of time after the power of the main heater is reduced, and determine whether to increase the power of the main heater.

[0012] Preferably, in step S10, collecting a training data set in the temperature control process and establishing a temperature control model includes:

[0013] A large number of historical sample parameters are obtained to obtain a training data set related to the bottom main heater power and the heater power; based on the training data set, a neural network model is trained to obtain a temperature control model; the historical sample parameters include the total amount of silicon material input, the time for re-injection of silicon material, the time from the last bucket of silicon material input to the bottom heater being turned off, the time from the bottom heater being turned off to the silicon material being fully melted, and the rate of change of the solid-liquid ratio over time.

[0014] Preferably, in step S10, the method for obtaining the average solid-liquid ratio in the single crystal furnace within a period of time and the fluctuation of the solid-liquid ratio over time includes:

[0015] Step S101, obtaining n images of the liquid surface in the single crystal furnace within time T1 by using a furnace table CCD camera;

[0016] Step S102, identifying solid blocks and liquids in each liquid surface image through a visual server, and annotating information of the solid blocks and liquids, so as to obtain a solid-liquid ratio of each liquid surface image;

[0017] Step S103, calculating the average value of the solid-liquid ratio of all liquid surface images as the average solid-liquid ratio in the single crystal furnace in the current time period;

[0018] Step S104, arrange the solid-liquid ratios corresponding to all liquid surface images in chronological order, obtain the solid-liquid ratio fluctuation amplitude values ​​of all liquid surface images taken at two adjacent time points, calculate the average fluctuation amplitude value of all fluctuation amplitude values, and thereby obtain the fluctuation of the solid-liquid ratio over time.

[0019] Preferably, in the step S20, based on the fluctuation of the solid-liquid ratio over time, controlling the lifting and lowering of the guide tube includes:

[0020] The average fluctuation amplitude value is compared with the preset fluctuation threshold. If the solid-liquid ratio fluctuation amplitude is within the preset fluctuation threshold, the guide cylinder is stopped from being lowered, and an alarm is sounded to prompt the staff to check whether the solid material blocks are stuck to the guide cylinder; if the solid-liquid ratio fluctuation amplitude is not within the preset fluctuation threshold, the guide cylinder is kept descending.

[0021] Preferably, the staff checks whether the solid material blocks are adhered to the guide tube, including:

[0022] If the solid material block is adhered to the guide tube, the guide tube is lifted to separate the solid material block; if the solid material block is not adhered to the guide tube, the downward movement of the guide tube is maintained.

[0023] Preferably, in step S20, the average solid-liquid ratio is sent to a temperature control model, and the adjustment of the heater is controlled by the output result of the temperature control model, including:

[0024] When the visual server recognizes that liquid appears in the liquid surface image, a first average solid-liquid ratio in the single crystal furnace within a period of time is obtained; the first average solid-liquid ratio is sent to the temperature control model, and when the first average solid-liquid ratio reaches a preset solid-liquid ratio threshold for reducing the bottom heater power in the temperature control model, the temperature control model outputs the time and adjustment amplitude parameters for reducing the bottom heater power;

[0025] After reducing the power of the bottom heater, the average solid-liquid ratio in the single crystal furnace over a period of time is re-obtained as the second average solid-liquid ratio. When the second average solid-liquid ratio reaches the preset solid-liquid ratio threshold for shutting down the bottom heater in the temperature control model, the temperature control model outputs the time to shut down the bottom heater.

[0026] Preferably, in step S30, whether to turn on the bottom heater for the second time includes:

[0027] The solid-liquid ratio in the single crystal furnace when the bottom heater is turned off is obtained as the first solid-liquid ratio. After the bottom heater is turned off, the average solid-liquid ratio in the single crystal furnace over a period of time is obtained as the third average solid-liquid ratio; the third average solid-liquid ratio is compared with the first solid-liquid ratio to determine whether to turn on the bottom heater for the second time;

[0028] If the third average solid-liquid ratio is smaller than the first solid-liquid ratio, it means that the solid material blocks in the single crystal furnace float out of the imaging range of the furnace table CCD camera, and the bottom heater remains closed; if the third average solid-liquid ratio is greater than the first solid-liquid ratio, it means that the solid material blocks in the single crystal furnace float back into the imaging range of the furnace table CCD camera, and the temperature control model outputs the time and adjustment amplitude parameters for turning on the bottom heater for the second time.

[0029] Preferably, if the bottom heater remains off, the third average solid-liquid ratio is sent to the temperature control model, and when the third average solid-liquid ratio reaches a preset solid-liquid ratio threshold for reducing the main heater power in the temperature control model, the temperature control model outputs the time and adjustment amplitude parameters for reducing the main heater power;

[0030] If the bottom heater is turned on for the second time, the average solid-liquid ratio in the single crystal furnace within a period of time after the bottom heater is turned on for the second time is obtained as the fourth average solid-liquid ratio, and the fourth average solid-liquid ratio is sent to the temperature control model. When the fourth average solid-liquid ratio reaches the preset solid-liquid ratio threshold for reducing the main heater power in the temperature control model, the temperature control model outputs the time and adjustment amplitude parameters for reducing the main heater power.

[0031] Preferably, in step S40, performing the crucible positioning operation includes:

[0032] After reducing the power of the main heater, the guide tube continues to descend until it reaches the lower limit position, raising the crucible to complete the crucible positioning operation.

[0033] Preferably, in step S40, whether to increase the power of the main heater includes:

[0034] The solid-liquid ratio in the single crystal furnace when the power of the main heater is reduced is obtained as the second solid-liquid ratio. After the power of the main heater is reduced, the average solid-liquid ratio in the single crystal furnace over a period of time is obtained as the fifth average solid-liquid ratio. The second solid-liquid ratio and the fifth average solid-liquid ratio are compared to determine whether to increase the power of the main heater;

[0035] If the fifth average solid-liquid ratio is smaller than the second solid-liquid ratio, it means that the solid material blocks in the single crystal furnace float out of the imaging range of the furnace table CCD camera, and the main heater power is kept at a reduced state; if the fifth average solid-liquid ratio is greater than the second solid-liquid ratio, it means that the solid material blocks in the single crystal furnace float back into the imaging range of the furnace table CCD camera, and the temperature control model outputs the time and adjustment amplitude parameters for increasing the main heater power.

[0036] Compared with the prior art, the beneficial effects of the present invention are: detecting the solid-liquid ratio in the single crystal furnace through the visual server, and indirectly judging whether the material block is stationary through the fluctuation of the solid-liquid ratio within a period of time, so that the staff can promptly detect the material block stuck to the guide tube, reducing the possibility of accidents; using the average solid-liquid ratio to trigger the temperature control model to adjust and control the heater, so as to realize the temperature control of the single crystal furnace crystal pulling; and judging whether the material block floats out of the photographic field of view through the solid-liquid ratio, so as to decide whether to turn on the bottom heater for the second time and increase the power of the main heater, avoiding the situation where insufficient heat in the furnace affects the subsequent material processing, and ensuring that the liquid temperature is within the standard range after the crucible position is determined. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 A schematic flow chart of a crystal pulling temperature control method for a single crystal furnace provided by the present invention;

[0039] Figure 2 This is a flow chart of obtaining the average solid-liquid ratio and the fluctuation of the solid-liquid ratio over time in step S10 of the crystal pulling temperature control method of the single crystal furnace provided by the present invention. DETAILED DESCRIPTION

[0040] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0041] The term "comprise" and any variation thereof in this application is intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0043] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0044] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0045] Figure 1 The present invention provides a flow chart of a method for controlling the crystal pulling temperature of a single crystal furnace. The method for controlling the crystal pulling temperature of a single crystal furnace comprises the following steps:

[0046] Step S10, collecting a training data set in the temperature control process, and establishing a temperature control model based on the training data set; obtaining the solid-liquid ratio in the single crystal furnace for multiple times, and obtaining the average solid-liquid ratio in the single crystal furnace over a period of time and the fluctuation of the solid-liquid ratio over time;

[0047] Step S20, based on the fluctuation of the solid-liquid ratio over time, controlling the lifting and lowering of the guide tube; sending the average solid-liquid ratio to the temperature control model, and controlling the adjustment of the heater based on the output result of the temperature control model, wherein the adjustment of the heater includes reducing the power of the bottom heater, turning off the bottom heater, turning on the bottom heater twice, reducing the power of the main heater, and increasing the power of the main heater;

[0048] Step S30, obtaining the solid-liquid ratio in the single crystal furnace when the bottom heater is turned off and the average solid-liquid ratio in the single crystal furnace within a period of time after the bottom heater is turned off, and determining whether to turn on the bottom heater again;

[0049] Step S40, after reducing the power of the main heater, perform the crucible positioning operation; and obtain the solid-liquid ratio in the single crystal furnace when the power of the main heater is reduced and the average solid-liquid ratio in the single crystal furnace for a period of time after the power of the main heater is reduced, and determine whether to increase the power of the main heater.

[0050] The crystal pulling temperature control method of the single crystal furnace detects the solid-liquid ratio in the single crystal furnace through the visual server, and indirectly judges whether the material block is stationary through the fluctuation of the solid-liquid ratio over a period of time, so that the staff can timely detect the material block stuck to the guide tube, reducing the possibility of accidents; at the same time, the solid-liquid ratio is sent to the temperature control model, and the average solid-liquid ratio is used to trigger the temperature control model to adjust and control the heater, thereby realizing the temperature control of the single crystal furnace crystal pulling; and the solid-liquid ratio is used to judge whether the material block floats out of the photographic field of view, so as to decide whether to re-open the bottom heater and re-raise the main heater, thereby avoiding the situation where insufficient heat in the furnace affects the subsequent material processing, and ensuring that the liquid temperature is within the standard range after the crucible position is determined.

[0051] Furthermore, in step S10, a training data set in the temperature control process is collected, and establishing a temperature control model includes:

[0052] A large number of historical sample parameters are obtained to obtain a training data set related to the bottom main heater power and the heater power; based on the training data set, a neural network model is trained to obtain a temperature control model; the historical sample parameters include the total amount of silicon material input, the time for re-injection of silicon material, the time from the last bucket of silicon material input to the bottom heater being turned off, the time from the bottom heater being turned off to the silicon material being fully melted, and the rate of change of the solid-liquid ratio over time.

[0053] In the above technical solution, a large number of different and reference historical sample parameters are collected to obtain a training data set related to the bottom main heater power and the heater power. This can make the obtained training data set accurate and effective, thereby providing a reliable data source for the temperature control model.

[0054] In order to ensure the accuracy of the measured solid-liquid ratio and prevent the melting of silicon materials from being affected, the average solid-liquid ratio over a period of time needs to be used when adjusting and controlling the heater. When controlling the lifting and lowering of the guide tube, the average fluctuation amplitude over a period of time also needs to be used. Figure 2 , a method for obtaining the average solid-liquid ratio in a single crystal furnace over a period of time and the fluctuation of the solid-liquid ratio over time, including:

[0055] Step S101, obtaining n images of the liquid surface in the single crystal furnace within time T1 by using a furnace table CCD camera;

[0056] Step S102, identifying solid blocks and liquids in each liquid surface image through a visual server, and labeling the solid blocks and liquids to obtain a solid-liquid ratio of each liquid surface image;

[0057] Step S103, calculating the average value of the solid-liquid ratio of all liquid surface images as the average solid-liquid ratio in the single crystal furnace in the current time period;

[0058] Step S104, arrange the solid-liquid ratios corresponding to all liquid surface images in chronological order, obtain the solid-liquid ratio fluctuation amplitude values ​​of all liquid surface images taken at two adjacent time points, calculate the average fluctuation amplitude value of all fluctuation amplitude values, and thereby obtain the fluctuation of the solid-liquid ratio over time.

[0059] In the above technical scheme, the furnace CCD camera transmits the acquired liquid level image in the single crystal furnace to the visual server, and the visual server identifies and marks the solid blocks and liquids in each liquid level image, and calculates the corresponding solid-liquid ratio; due to the difference in grayscale between the solid blocks and the liquid in the furnace, the visual server can mark the information by distinguishing the grayscale of the solid blocks and the liquid, wherein the liquid marked by the visual server includes silicon materials in liquid state and thin film state, further ensuring the data accuracy of the solid-liquid ratio; in addition, when the single crystal furnace is full of solid blocks or the solid blocks are in a fully molten state, the solid-liquid ratio in the furnace is not detected, thereby reducing the workload of the visual server; by calculating the average value of the solid-liquid ratio corresponding to the n liquid level images taken by the furnace CCD camera, the average solid-liquid ratio in the single crystal furnace within time T1 can be obtained, and the solid-liquid ratios corresponding to the n liquid level images are arranged in chronological order to obtain the solid-liquid ratio fluctuation amplitude values ​​of all liquid level images taken at two adjacent time points, and the average fluctuation amplitude value of all fluctuation amplitude values ​​is calculated to ensure the validity of the data.

[0060] It should be noted that time T1 is an open parameter and is set according to the actual thermal field conditions of the single crystal furnace.

[0061] Furthermore, in step S20, based on the fluctuation of the solid-liquid ratio over time, the lifting and lowering of the guide tube is controlled, including:

[0062] The average fluctuation amplitude value is compared with the preset fluctuation threshold. If the solid-liquid ratio fluctuation amplitude is within the preset fluctuation threshold, the guide tube is stopped from descending, and an alarm is sounded to remind the staff to check whether the solid material blocks are stuck to the guide tube; if the solid-liquid ratio fluctuation amplitude is not within the preset fluctuation threshold, the guide tube is kept descending.

[0063] In the above technical solution, after a part of the solid material block is melted, the material block will float on the liquid surface, and the operator will turn the silicon material in the furnace over so that the silicon material can be heated evenly. However, if the solid material block below the liquid surface is relatively high, it will hit the guide tube, causing the obtained solid-liquid ratio data to be abnormal. The visual server is used to detect the solid-liquid ratio in the single crystal furnace throughout the process, and the fluctuation of the solid-liquid ratio over a period of time is used to indirectly determine whether the material block is stationary, so that the staff can promptly detect the material block stuck to the guide tube, reducing the possibility of accidents.

[0064] Furthermore, the staff checked whether the solid blocks were stuck to the guide tube, including:

[0065] If the solid material block is adhered to the guide tube, the guide tube is lifted to separate the solid material block; if the solid material block is not adhered to the guide tube, the downward movement of the guide tube is maintained.

[0066] In the above technical solution, when the solid material block sticks to the guide tube, the solid material block can be separated by raising the guide tube; if the solid material block still cannot be separated after the guide tube is raised, it is necessary to increase the power of the main heater for remelting to separate the solid material block from the guide tube.

[0067] Furthermore, in step S20, the average solid-liquid ratio is sent to the temperature control model, and the adjustment of the heater is controlled by the output result of the temperature control model, including:

[0068] When the visual server recognizes that liquid appears in the liquid surface image, a first average solid-liquid ratio in the single crystal furnace within a period of time is obtained; the first average solid-liquid ratio is sent to the temperature control model, and when the first average solid-liquid ratio reaches a preset solid-liquid ratio threshold for reducing the bottom heater power in the temperature control model, the temperature control model outputs the time and adjustment amplitude parameters for reducing the bottom heater power;

[0069] After reducing the power of the bottom heater, the average solid-liquid ratio in the single crystal furnace over a period of time is re-obtained as the second average solid-liquid ratio. When the second average solid-liquid ratio reaches the preset solid-liquid ratio threshold for shutting down the bottom heater in the temperature control model, the temperature control model outputs the time to shut down the bottom heater.

[0070] In the above technical scheme, the temperature control model is triggered by the average solid-liquid ratio to adjust and control the bottom heater and the main heater, thereby realizing the temperature control of the single crystal furnace pulling crystal; the temperature control model will not only output the amplitude parameters of the adjustment heater, but also output the adjustment time to ensure accurate control of the temperature in the furnace.

[0071] Further, in step S30, whether to turn on the bottom heater for a second time includes:

[0072] The solid-liquid ratio in the single crystal furnace when the bottom heater is turned off is obtained as the first solid-liquid ratio. After the bottom heater is turned off, the average solid-liquid ratio in the single crystal furnace over a period of time is obtained as the third average solid-liquid ratio. The third average solid-liquid ratio is compared with the first solid-liquid ratio to determine whether to turn on the bottom heater for the second time.

[0073] If the third average solid-liquid ratio is smaller than the first solid-liquid ratio, it means that the solid material blocks in the single crystal furnace float out of the imaging range of the furnace table CCD camera, and the bottom heater remains closed; if the third average solid-liquid ratio is greater than the first solid-liquid ratio, it means that the solid material blocks in the single crystal furnace float back into the imaging range of the furnace table CCD camera, and the temperature control model outputs the time and adjustment amplitude parameters for opening the bottom heater for the second time.

[0074] In the above technical scheme, by comparing the solid-liquid ratio in the furnace when the heater was adjusted last time with the average solid-liquid ratio in a period of time after the heater was adjusted, it is determined whether the material block has floated out of the photographic field of view of the CCD camera, thereby deciding whether to turn on the bottom heater for the second time, thereby avoiding the situation where insufficient heat in the furnace affects the subsequent chemical reaction of the solid material block; due to the lifting and lowering of the guide tube, the visual server can not only identify the solid material block and liquid when identifying the liquid surface image, but also identify the irrelevant area, which is the area blocked by the guide tube. Whether the material block floats out of the photographic field of view of the CCD camera means that the solid material block floats into the irrelevant area.

[0075] Further, if the bottom heater remains off, the third average solid-liquid ratio is sent to the temperature control model, and when the third average solid-liquid ratio reaches a preset solid-liquid ratio threshold for reducing the power of the main heater in the temperature control model, the temperature control model outputs the time and adjustment amplitude parameters for reducing the power of the main heater;

[0076] If the bottom heater is turned on for the second time, the average solid-liquid ratio in the single crystal furnace within a period of time after the bottom heater is turned on for the second time is obtained as the fourth average solid-liquid ratio, and the fourth average solid-liquid ratio is sent to the temperature control model. When the fourth average solid-liquid ratio reaches the preset solid-liquid ratio threshold for reducing the main heater power in the temperature control model, the temperature control model outputs the time and adjustment amplitude parameters for reducing the main heater power.

[0077] In the above technical solution, the solid material block continues to melt. When the average solid-liquid ratio in the single crystal furnace over a period of time reaches the preset solid-liquid ratio threshold for reducing the main heater power in the temperature control model, the temperature control model outputs the time and adjustment amplitude parameters for reducing the main heater power to prevent the furnace temperature from being too high and affecting the crystal quality.

[0078] Further, in step S40, performing the crucible positioning operation includes:

[0079] After reducing the power of the main heater, the guide tube continues to descend until it reaches the lower limit position, raising the crucible to complete the crucible positioning operation.

[0080] In the above technical solution, the entire temperature control method includes the crucible positioning operation and the adjustment of the heater by the temperature control model, and both are performed simultaneously to ensure that the solid material blocks can be completely melted while the guide tube and / or the crucible are raised, thereby ensuring that the liquid temperature is within the standard range after the crucible is positioned.

[0081] Further, in step S40, whether to increase the power of the main heater includes:

[0082] The solid-liquid ratio in the single crystal furnace when the power of the main heater is reduced is obtained as the second solid-liquid ratio. After the power of the main heater is reduced, the average solid-liquid ratio in the single crystal furnace over a period of time is obtained as the fifth average solid-liquid ratio. The second solid-liquid ratio is compared with the fifth average solid-liquid ratio to determine whether to increase the power of the main heater.

[0083] If the fifth average solid-liquid ratio is smaller than the second solid-liquid ratio, it means that the solid material blocks in the single crystal furnace float out of the imaging range of the furnace table CCD camera, and the main heater power is kept at a reduced state; if the fifth average solid-liquid ratio is greater than the second solid-liquid ratio, it means that the solid material blocks in the single crystal furnace float back into the imaging range of the furnace table CCD camera, and the temperature control model outputs the time and adjustment amplitude parameters for increasing the main heater power.

[0084] In the above technical scheme, by comparing the solid-liquid ratio in the furnace when the main heater power is reduced with the average solid-liquid ratio in the single crystal furnace within a period of time after the main heater power is reduced, it is determined whether the material block floats out of the photographic field of view of the CCD camera, thereby deciding whether to increase the main heater power, thereby avoiding the situation where insufficient heat in the furnace affects the chemical reaction of the solid material block and preventing the appearance of solid material blocks blocked by the guide tube.

[0085] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for controlling the crystal pulling temperature of a single crystal furnace, characterized in that: It includes the following steps: Step S10, collecting a training data set in the temperature control process, and establishing a temperature control model based on the training data set; obtaining the solid-liquid ratio in the single crystal furnace for multiple times, and obtaining the average solid-liquid ratio in the single crystal furnace over a period of time and the fluctuation of the solid-liquid ratio over time; Step S20, based on the fluctuation of the solid-liquid ratio over time, controlling the lifting and lowering of the guide tube; sending the average solid-liquid ratio to the temperature control model, and controlling the adjustment of the heater based on the output result of the temperature control model, wherein the adjustment of the heater includes reducing the power of the bottom heater, turning off the bottom heater, turning on the bottom heater twice, reducing the power of the main heater, and increasing the power of the main heater; Step S30, obtaining the solid-liquid ratio in the single crystal furnace when the bottom heater is turned off and the average solid-liquid ratio in the single crystal furnace within a period of time after the bottom heater is turned off, and determining whether to turn on the bottom heater again; Step S40, after reducing the power of the main heater, perform the crucible positioning operation; and obtain the solid-liquid ratio in the single crystal furnace when the power of the main heater is reduced and the average solid-liquid ratio in the single crystal furnace for a period of time after the power of the main heater is reduced, and determine whether to increase the power of the main heater.

2. The crystal pulling temperature control method of a single crystal furnace according to claim 1, characterized in that: In step S10, a training data set in the temperature control process is collected to establish a temperature control model, including: A large number of historical sample parameters are obtained to obtain a training data set related to the bottom main heater power and the heater power; based on the training data set, a neural network model is trained to obtain a temperature control model; the historical sample parameters include the total amount of silicon material input, the time for re-injection of silicon material, the time from the last bucket of silicon material input to the bottom heater being turned off, the time from the bottom heater being turned off to the silicon material being fully melted, and the rate of change of the solid-liquid ratio over time.

3. The crystal pulling temperature control method of a single crystal furnace according to claim 2, characterized in that: In the step S10, the method for obtaining the average solid-liquid ratio in the single crystal furnace within a period of time and the fluctuation of the solid-liquid ratio over time includes: Step S101, using a furnace table CCD camera to obtain n images of the liquid surface in the single crystal furnace within time T1; Step S102, identifying solid blocks and liquids in each liquid surface image through a visual server, and annotating information of the solid blocks and liquids, so as to obtain a solid-liquid ratio of each liquid surface image; Step S103, calculating the average value of the solid-liquid ratio of all liquid surface images as the average solid-liquid ratio in the single crystal furnace in the current time period; Step S104, arrange the solid-liquid ratios corresponding to all liquid surface images in chronological order, obtain the solid-liquid ratio fluctuation amplitude values ​​of all liquid surface images taken at two adjacent time points, calculate the average fluctuation amplitude value of all fluctuation amplitude values, and thereby obtain the fluctuation of the solid-liquid ratio over time.

4. The crystal pulling temperature control method of a single crystal furnace according to claim 3, characterized in that: In the step S20, based on the fluctuation of the solid-liquid ratio over time, the lifting and lowering of the guide tube is controlled, including: The average fluctuation amplitude value is compared with the preset fluctuation threshold. If the solid-liquid ratio fluctuation amplitude is within the preset fluctuation threshold, the guide cylinder is stopped from being lowered, and an alarm is sounded to prompt the staff to check whether the solid material blocks are stuck to the guide cylinder; if the solid-liquid ratio fluctuation amplitude is not within the preset fluctuation threshold, the guide cylinder is kept descending.

5. The crystal pulling temperature control method of a single crystal furnace according to claim 4, characterized in that: The staff checked whether the solid blocks were stuck to the guide tube, including: If the solid material block is adhered to the guide tube, the guide tube is lifted to separate the solid material block; if the solid material block is not adhered to the guide tube, the downward movement of the guide tube is maintained.

6. The crystal pulling temperature control method of a single crystal furnace according to claim 3, characterized in that: In the step S20, the average solid-liquid ratio is sent to the temperature control model, and the adjustment of the heater is controlled by the output result of the temperature control model, including: When the visual server recognizes that liquid appears in the liquid surface image, a first average solid-liquid ratio in the single crystal furnace within a period of time is obtained; the first average solid-liquid ratio is sent to the temperature control model, and when the first average solid-liquid ratio reaches a preset solid-liquid ratio threshold for reducing the bottom heater power in the temperature control model, the temperature control model outputs the time and adjustment amplitude parameters for reducing the bottom heater power; After reducing the power of the bottom heater, the average solid-liquid ratio in the single crystal furnace over a period of time is re-obtained as the second average solid-liquid ratio. When the second average solid-liquid ratio reaches the preset solid-liquid ratio threshold for shutting down the bottom heater in the temperature control model, the temperature control model outputs the time to shut down the bottom heater.

7. The crystal pulling temperature control method of a single crystal furnace according to claim 6, characterized in that: In the step S30, whether to turn on the bottom heater for the second time includes: The solid-liquid ratio in the single crystal furnace when the bottom heater is turned off is obtained as the first solid-liquid ratio. After the bottom heater is turned off, the average solid-liquid ratio in the single crystal furnace over a period of time is obtained as the third average solid-liquid ratio; the third average solid-liquid ratio is compared with the first solid-liquid ratio to determine whether to turn on the bottom heater for the second time; If the third average solid-liquid ratio is smaller than the first solid-liquid ratio, it means that the solid material blocks in the single crystal furnace float out of the imaging range of the furnace table CCD camera, and the bottom heater remains closed; if the third average solid-liquid ratio is greater than the first solid-liquid ratio, it means that the solid material blocks in the single crystal furnace float back into the imaging range of the furnace table CCD camera, and the temperature control model outputs the time and adjustment amplitude parameters for turning on the bottom heater for the second time.

8. The crystal pulling temperature control method of a single crystal furnace according to claim 7, characterized in that: If the bottom heater remains off, the third average solid-liquid ratio is sent to the temperature control model, and when the third average solid-liquid ratio reaches a preset solid-liquid ratio threshold for reducing the power of the main heater in the temperature control model, the temperature control model outputs the time and adjustment amplitude parameters for reducing the power of the main heater; If the bottom heater is turned on for the second time, the average solid-liquid ratio in the single crystal furnace within a period of time after the bottom heater is turned on for the second time is obtained as the fourth average solid-liquid ratio, and the fourth average solid-liquid ratio is sent to the temperature control model. When the fourth average solid-liquid ratio reaches the preset solid-liquid ratio threshold for reducing the main heater power in the temperature control model, the temperature control model outputs the time and adjustment amplitude parameters for reducing the main heater power.

9. The crystal pulling temperature control method of a single crystal furnace according to claim 8, characterized in that: In the step S40, the crucible positioning operation includes: After reducing the power of the main heater, the guide tube continues to descend until it reaches the lower limit position, raising the crucible to complete the crucible positioning operation.

10. The crystal pulling temperature control method of a single crystal furnace according to claim 8, characterized in that: In the step S40, whether to increase the power of the main heater includes: The solid-liquid ratio in the single crystal furnace when the power of the main heater is reduced is obtained as the second solid-liquid ratio. After the power of the main heater is reduced, the average solid-liquid ratio in the single crystal furnace over a period of time is obtained as the fifth average solid-liquid ratio. The second solid-liquid ratio and the fifth average solid-liquid ratio are compared to determine whether to increase the power of the main heater; If the fifth average solid-liquid ratio is smaller than the second solid-liquid ratio, it means that the solid material blocks in the single crystal furnace float out of the imaging range of the furnace table CCD camera, and the main heater power is kept at a reduced state; if the fifth average solid-liquid ratio is greater than the second solid-liquid ratio, it means that the solid material blocks in the single crystal furnace float back into the imaging range of the furnace table CCD camera, and the temperature control model outputs the time and adjustment amplitude parameters for increasing the main heater power.

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