Temperature control system for crystal furnace and control method thereof

Abstract

The invention relates to the technical field of crystal furnaces, in particular to a temperature control system and method for a crystal furnace, and the method comprises the steps: setting the target temperature of the crystal furnace, heating the crystal furnace through a heater, and monitoring the internal temperature of the crystal furnace in real time through a temperature sensor; crystal growth is guided through seed crystals in the crystal furnace, and airflow distribution in the crystal furnace is guided through a guide plate; determining whether the temperature control stability of the crystal furnace meets the requirement or not based on the maximum temperature difference quantity in the crystal furnace; if the temperature control stability of the crystal furnace does not meet the requirement, whether the duty ratio of a heater needs to be increased or not is determined; determining whether thermal management in the crystal furnace meets requirements based on the growth rate of the crystal in the crystal furnace; determining whether the rotation speed of the seed crystal needs to be increased; and determining whether the angle of the guide plate in the crystal furnace needs to be increased based on the fluctuation amplitude of the pressure in the crystal furnace. The temperature control stability of the crystal furnace is improved.

Description

Technical Field

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

[0002] High-quality single-crystal silicon is the foundation for manufacturing high-performance chips. The integrity and purity of its crystal structure directly determine the chip's computing speed and stability. In the field of optics, the crystals used to manufacture precision optical devices must have extremely low internal defects and uniform optical properties, which also depends on precise control of crystal growth conditions. As a key piece of equipment for crystal growth, the precision and stability of temperature control in a crystal furnace are crucial. Traditional methods for controlling crystal furnace temperature have numerous limitations. Early, simple open-loop control methods were unable to sense temperature changes within the furnace in real time and struggled to cope with complex heat transfer processes and environmental interference. This resulted in large temperature fluctuations during crystal growth and inconsistent crystal quality. Later developments of closed-loop control methods, while improving temperature control accuracy to a certain extent, still struggled to cope with the complex thermal field variations caused by various factors during crystal growth.

[0003] Chinese Patent Publication No.: CN117468079A discloses a control method for a temperature control system of a crucible drop method crystal growth furnace, the temperature control system including a PLC controller, a first SCR power regulator, a second SCR power regulator, a first heating rod located in the upper temperature zone of the growth furnace, a first high-precision thermocouple located in the upper temperature zone of the growth furnace, a second heating rod located in the lower temperature zone of the growth furnace, and a second high-precision thermocouple located in the lower temperature zone of the growth furnace. The PLC controller is provided with a PLC analog input and output module, the output ends of the first high-precision thermocouple and the second high-precision thermocouple are connected to the input end of the PLC analog input and output module, the first SCR power regulator and the second SCR power regulator are respectively connected to the output end of the PLC analog input and output module, the output end of the first SCR power regulator is electrically connected to the control end of the first heating rod, and the output end of the second SCR power regulator is electrically connected to the control end of the second heating rod. It can be seen that the control method of the temperature control system of the crucible descent method crystal growth furnace has the problem that the first high-precision thermocouple and the second high-precision thermocouple will experience accuracy drift when working in a long-term high-temperature environment, resulting in inaccurate temperature data fed back to the PLC controller, thereby making it impossible for the temperature control system to accurately adjust the heating power. Summary of the Invention

[0004] To this end, the present invention provides a temperature control system and a control method for a crystal furnace, which are used to overcome the problem in the prior art that the first high-precision thermocouple and the second high-precision thermocouple may drift in accuracy when working in a long-term high-temperature environment, resulting in inaccurate temperature data fed back to the PLC controller, thereby making it impossible for the temperature control system to accurately adjust the heating power.

[0005] To achieve the above object, the present invention provides a temperature control method for a crystal furnace, comprising: Setting a target temperature of the crystal furnace, heating the crystal furnace by a heater, and monitoring the internal temperature of the crystal furnace in real time using a temperature sensor; guiding crystal growth through the seed crystal in the crystal furnace, and guiding the airflow distribution in the crystal furnace using a guide plate; Obtaining the temperature in the crystal furnace and calculating the maximum temperature difference in the crystal furnace; determining whether the temperature control stability of the crystal furnace meets the requirements based on the maximum temperature difference in the crystal furnace; If the temperature control stability of the crystal furnace does not meet the requirements, determining whether it is necessary to increase the duty cycle of the heater; If the duty cycle of the heater does not need to be increased, determining whether the thermal management in the crystal furnace meets the requirements based on the growth rate of the crystal in the crystal furnace; If the thermal management in the crystal furnace does not meet the requirements, determining whether it is necessary to increase the rotation speed of the seed crystal; If the rotation speed of the seed crystal does not need to be increased, whether the angle of the guide plate in the crystal furnace needs to be increased is determined based on the fluctuation amplitude of the pressure in the crystal furnace.

[0006] Further, determining whether the temperature control stability of the crystal furnace meets the requirements based on the maximum temperature difference in the crystal furnace includes: Comparing the maximum temperature difference in the crystal furnace with a preset first temperature difference; If the maximum temperature difference in the crystal furnace is less than or equal to the preset first difference, it is determined that the temperature control stability of the crystal furnace meets the requirements; If the maximum temperature difference in the crystal furnace is greater than the preset first difference, it is determined that the temperature control stability of the crystal furnace does not meet the requirements.

[0007] Furthermore, determining whether the duty cycle of the heater needs to be increased includes: Comparing the maximum temperature difference in the crystal furnace with the preset first difference and the preset second difference respectively; If the maximum temperature difference in the crystal furnace is greater than the preset second difference, determining that the duty cycle of the heater needs to be increased, and increasing the duty cycle of the heater; If the maximum temperature difference in the crystal furnace is greater than the preset first difference and less than or equal to the preset second difference, it is determined that there is no need to increase the duty cycle of the heater.

[0008] Furthermore, the increase range of the duty cycle of the heater is proportional to the difference between the maximum temperature difference in the crystal furnace and the preset second temperature difference.

[0009] Furthermore, determining whether the thermal management in the crystal furnace meets the requirements based on the growth rate of the crystal in the crystal furnace includes: comparing the growth rate of the crystal in the crystal furnace with a preset second growth rate; If the growth rate of the crystal in the crystal furnace is greater than the preset second growth rate, determining that the thermal management in the crystal furnace meets the requirements, and determining whether the duty cycle of the heater meets the requirements; If the growth rate of the crystal in the crystal furnace is less than or equal to the preset second growth rate, it is determined that the thermal management in the crystal furnace does not meet the requirements.

[0010] Furthermore, determining whether it is necessary to increase the rotation speed of the seed crystal includes: Comparing the growth rate of the crystal in the crystal furnace with the preset first growth rate and the preset second growth rate respectively; If the growth rate of the crystal in the crystal furnace is greater than the preset first growth rate and less than or equal to the preset second growth rate, it is determined that the rotation speed of the seed crystal needs to be increased, and the rotation speed of the seed crystal is increased; If the growth rate of the crystal in the crystal furnace is less than or equal to the preset first growth rate, it is determined that there is no need to increase the rotation speed of the seed crystal.

[0011] Furthermore, the increase in the rotation speed of the seed crystal is proportional to the difference between the growth rate of the crystal in the crystal furnace and the preset first growth rate.

[0012] Furthermore, determining whether it is necessary to increase the angle of the guide plate in the crystal furnace based on the fluctuation amplitude of the pressure in the crystal furnace includes: Compare the fluctuation amplitude of the pressure in the crystal furnace with the preset fluctuation amplitude; If the fluctuation amplitude of the pressure in the crystal furnace is less than or equal to the preset fluctuation amplitude, it is determined that there is no need to increase the angle of the guide plate in the crystal furnace, and whether the rotation speed of the seed crystal meets the requirement; If the fluctuation amplitude of the pressure in the crystal furnace is greater than the preset fluctuation amplitude, it is determined that the angle of the guide plate in the crystal furnace needs to be increased, and the angle of the guide plate in the crystal furnace is increased.

[0013] Furthermore, the increase in the angle of the guide plate in the crystal furnace is proportional to the difference between the fluctuation amplitude of the pressure in the crystal furnace and the preset fluctuation amplitude.

[0014] The present invention also provides a temperature control system for a crystal furnace, comprising: A crystal growth module, for growing crystals using a crystal furnace, comprising a seed crystal disposed inside the crystal furnace for guiding the growth of the crystal and a guide plate disposed inside the crystal furnace for guiding internal airflow distribution; a detection module connected to the crystal growth module, comprising a temperature sensor disposed inside the crystal furnace for detecting the temperature inside the crystal furnace and a pressure sensor disposed inside the crystal furnace for monitoring the internal pressure of the crystal furnace; A control module is connected to the crystal growth module and the detection module respectively, and is used to determine the duty cycle of the heater according to the maximum temperature difference in the crystal furnace, or to determine the rotation speed of the seed crystal according to the growth rate of the crystal in the crystal furnace, and to determine the angle of the guide plate in the crystal furnace according to the fluctuation amplitude of the pressure in the crystal furnace.

[0015] Compared with the prior art, the beneficial effect of the present invention is that the method of the present invention adjusts the duty cycle of the heater according to the maximum temperature difference in the crystal furnace. Since the heating element may age after long-term use, resulting in reduced or uneven heating efficiency, the temperature difference between different parts of the crystal furnace increases. By increasing the duty cycle of the heater, the aged heating element can accumulate more heat per unit time, thereby improving the overall heating effect and compensating for the heat lost due to aging. The rotation speed of the seed crystal is adjusted according to the growth rate of the crystal in the crystal furnace. Since the furnace body of the crystal furnace is subjected to high temperature and mechanical stress for a long time, structural deformation, cracking and other problems may occur, resulting in part of the heat being transferred to the outside of the furnace body. By increasing the rotation speed of the seed crystal, the heat can be distributed more evenly in the furnace, reducing the local low temperature caused by heat transfer to the outside of the furnace body, and improving the temperature uniformity of the crystal growth environment. The angle of the guide plate in the crystal furnace is adjusted according to the fluctuation amplitude of the pressure in the crystal furnace. Since the exhaust duct of the crystal furnace is blocked by dust and impurities, the exhaust is not smooth, the gas accumulates in the furnace, and the pressure increases, which causes the gas flow to change and produces airflow disturbance. By increasing the angle of the guide plate in the crystal furnace, the gas can be more strongly guided in a specific direction, which helps to guide the locally accumulated gas to the exhaust port direction, improve the unevenness of the gas flow, reduce the airflow turbulence caused by gas accumulation, and improve the temperature control stability of the crystal furnace.

[0016] Furthermore, the method of the present invention adjusts the duty cycle of the heater by setting a preset first difference and a preset second difference. Since the heating element may age after long-term use, resulting in reduced or uneven heating efficiency, the temperature difference between different parts of the crystal furnace increases. By increasing the duty cycle of the heater, the aged heating element can accumulate more heat per unit time, thereby improving the overall heating effect, compensating for the heat lost due to aging, and further improving the temperature control stability of the crystal furnace.

[0017] Furthermore, the method of the present invention adjusts the rotation speed of the seed crystal by setting a preset first growth rate and a preset second growth rate. Since the furnace body of the crystal furnace may be subjected to structural deformation, cracking and other problems under the action of high temperature and mechanical stress for a long time, causing part of the heat to be transferred to the outside of the furnace body, by increasing the rotation speed of the seed crystal, the heat can be more evenly distributed in the furnace, reducing the local low temperature caused by heat transfer to the outside of the furnace body, improving the temperature uniformity of the crystal growth environment, and further improving the temperature control stability of the crystal furnace.

[0018] Furthermore, the method of the present invention adjusts the angle of the guide plate in the crystal furnace by setting a preset fluctuation amplitude. Since the exhaust duct of the crystal furnace is blocked by dust and impurities, resulting in poor exhaust, gas accumulates in the furnace and the pressure increases, causing changes in gas flow and generating airflow disturbances. By increasing the angle of the guide plate in the crystal furnace, the gas can be more strongly guided in a specific direction, which helps to guide the gas accumulated locally to the exhaust port direction, improve the unevenness of the gas flow, reduce the airflow turbulence caused by gas accumulation, and further improve the temperature control stability of the crystal furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is an overall flow chart of a temperature control method for a crystal furnace according to an embodiment of the present invention; Figure 2 This is a block diagram of the overall structure of a temperature control system for a crystal furnace according to an embodiment of the present invention; Figure 3 A logic flow chart of a process for determining whether to increase the duty cycle of a heater in a temperature control method for a crystal furnace according to an embodiment of the present invention; Figure 4 The present invention is a logic flow chart of a process for determining whether to increase the rotation speed of a seed crystal in a temperature control method for a crystal furnace according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0021] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0022] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0023] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0024] See also Figure 1 、 Figure 2 、 Figure 3 as well as Figure 4 As shown in the figure, they are respectively an overall flow chart of a temperature control system and a control method for a crystal furnace according to an embodiment of the present invention, an overall structural block diagram, a logic flow chart of a process for determining whether to increase the duty cycle of the heater, and a logic flow chart of a process for determining whether to increase the rotation speed of the seed crystal. A temperature control method for a crystal furnace according to the present invention comprises: Step S1, setting a target temperature of a crystal furnace, heating the crystal furnace by a heater, and using a temperature sensor to monitor the internal temperature of the crystal furnace in real time; Step S2, guiding crystal growth through the seed crystal in the crystal furnace, and using a guide plate to guide the airflow distribution in the crystal furnace; Step S3, obtaining the temperature in the crystal furnace and calculating the maximum temperature difference in the crystal furnace; Step S4, determining whether the temperature control stability of the crystal furnace meets the requirements based on the maximum temperature difference in the crystal furnace; Step S5, if the temperature control stability of the crystal furnace does not meet the requirements, determining whether it is necessary to increase the duty cycle of the heater; Step S6: if it is not necessary to increase the duty cycle of the heater, determining whether the thermal management in the crystal furnace meets the requirements based on the growth rate of the crystal in the crystal furnace; Step S7, if the thermal management in the crystal furnace does not meet the requirements, determining whether it is necessary to increase the rotation speed of the seed crystal; Step S8: If the rotation speed of the seed crystal does not need to be increased, determine whether the angle of the guide plate in the crystal furnace needs to be increased based on the fluctuation amplitude of the pressure in the crystal furnace.

[0025] Specifically, the heater includes a resistance heater, an induction heater, and a radio frequency heater.

[0026] Specifically, the crystals include silicon crystals, calcium fluoride crystals, and aluminum crystals.

[0027] In practice, the method of the present invention adjusts the duty cycle of the heater according to the maximum temperature difference in the crystal furnace. Since the heating element may age after long-term use, its heating efficiency may be reduced or uneven, which increases the temperature difference between different parts of the crystal furnace. By increasing the duty cycle of the heater, the aged heating element can accumulate more heat per unit time, thereby improving the overall heating effect and compensating for the heat lost due to aging. The rotation speed of the seed crystal is adjusted according to the growth rate of the crystal in the crystal furnace. Since the furnace body of the crystal furnace may experience structural deformation, cracking and other problems under the action of high temperature and mechanical stress for a long time, causing part of the heat to be transferred to the outside of the furnace body, by increasing the duty cycle of the seed crystal. The rotation speed can make the heat more evenly distributed in the furnace, reduce the local low temperature caused by heat transfer to the outside of the furnace body, improve the temperature uniformity of the crystal growth environment, and adjust the angle of the guide plate in the crystal furnace according to the fluctuation amplitude of the pressure in the crystal furnace. Since the exhaust duct of the crystal furnace is blocked by dust and impurities, the exhaust is not smooth, the gas accumulates in the furnace, and the pressure increases, which causes the gas flow to change and produces airflow disturbance. By increasing the angle of the guide plate in the crystal furnace, the gas can be more strongly guided in a specific direction, which helps to guide the locally accumulated gas to the exhaust port direction, improve the unevenness of the gas flow, reduce the airflow turbulence caused by gas accumulation, and improve the temperature control stability of the crystal furnace.

[0028] Specifically, determining whether the temperature control stability of the crystal furnace meets the requirements based on the maximum temperature difference in the crystal furnace includes: Comparing the maximum temperature difference in the crystal furnace with a preset first temperature difference; If the maximum temperature difference in the crystal furnace is less than or equal to the preset first difference, it is determined that the temperature control stability of the crystal furnace meets the requirements; If the maximum temperature difference in the crystal furnace is greater than the preset first difference, it is determined that the temperature control stability of the crystal furnace does not meet the requirements.

[0029] The cause of the crystal furnace's temperature control stability failing to meet requirements may be poor thermal management within the crystal furnace or an unsatisfactory heater duty cycle. The next step is to determine the specific cause. This process also determines whether the heater duty cycle needs to be increased.

[0030] Specifically, determining whether the heater duty cycle needs to be increased includes: Comparing the maximum temperature difference in the crystal furnace with the preset first difference and the preset second difference respectively; If the maximum temperature difference in the crystal furnace is greater than the preset second difference, determining that the duty cycle of the heater needs to be increased, and increasing the duty cycle of the heater; If the maximum temperature difference in the crystal furnace is greater than the preset first difference and less than or equal to the preset second difference, it is determined that there is no need to increase the duty cycle of the heater.

[0031] When the maximum temperature difference within the crystal furnace is greater than a preset second difference, it is determined that the cause of the crystal furnace's temperature control stability not meeting the requirements is that the heater's duty cycle does not meet the requirements, and therefore the heater's duty cycle needs to be increased. When the maximum temperature difference within the crystal furnace is greater than the preset second difference, it can be preliminarily determined that the thermal management within the crystal furnace does not meet the requirements. Next, it is necessary to make a final determination of whether the thermal management within the crystal furnace meets the requirements based on the growth rate of the crystals within the crystal furnace, that is, to determine whether the cause of the crystal furnace's temperature control stability not meeting the requirements is that the thermal management within the crystal furnace does not meet the requirements.

[0032] It can be understood that the preset first difference is smaller than the preset second difference, and the three intervals divided by the preset first difference and the preset second difference correspond to three situations respectively: The first interval is when the maximum temperature difference in the crystal furnace is less than or equal to the preset first difference. This corresponds to the situation where the temperature control stability of the crystal furnace meets the requirements and no adjustment is required. The second interval is when the maximum temperature difference in the crystal furnace is greater than the preset first difference and less than or equal to the preset second difference. This corresponds to the situation where the crystal furnace body may experience structural deformation and cracking due to long-term exposure to high temperature and mechanical stress, causing some heat to be transferred to the outside of the furnace body. In this case, it is necessary to further determine whether the thermal management of the crystal furnace meets the requirements. The third interval is that the maximum temperature difference in the crystal furnace is greater than the preset second difference. The corresponding situation is: since the heating element may age after long-term use, its heating efficiency will be reduced or uneven, which will increase the temperature difference in different parts of the crystal furnace. At this time, the duty cycle of the heater needs to be adjusted.

[0033] It is understandable that the settings of the preset first difference and the preset second difference can be set according to the actual working conditions. The settings of the preset first difference and the preset second difference are intended to ensure the control stability and practicality of the crystal furnace. Optionally, the preset first difference and the preset second difference are determined by evaluating the effects of different temperatures on the generation of crystals through a limited number of tests, and the determined preset first difference and the preset second difference should satisfy the requirements of being detectable by the temperature sensor without causing excessive interference to the operation of the crystal furnace. Exemplarily, the range of the preset first difference is generally selected from [2.5°C, 3.5°C], and the range of the preset second difference is generally selected from [4°C, 6°C].

[0034] Preferably, the first difference value is preset to be 3°C, and the second difference value is preset to be 5°C.

[0035] Specifically, the maximum temperature difference in the crystal furnace is the difference between the highest temperature and the lowest temperature at different positions in the crystal furnace at the same moment.

[0036] In implementation, the method of the present invention determines the temperature control stability of the crystal furnace by setting a preset first difference amount and a preset second difference amount, thereby reducing the impact of the decrease in the temperature control accuracy of the crystal furnace due to inaccurate determination of the temperature control stability of the crystal furnace, and further improving the temperature control stability of the crystal furnace.

[0037] Specifically, the increase range of the duty cycle of the heater is proportional to the difference between the maximum temperature difference in the crystal furnace and the preset second temperature difference.

[0038] Specifically, when the difference between the maximum temperature difference in the crystal furnace and the preset second difference is within 2°C, the duty cycle of the heater is increased to 1.1 times the original value; when the difference between the maximum temperature difference in the crystal furnace and the preset second difference exceeds 2°C, on the basis of being increased to 1.1 times the original value, the duty cycle of the heater is increased by 5% for every 0.5°C increase. For example, the difference between the maximum temperature difference in the crystal furnace and the preset second difference is 3°C, the current duty cycle of the heater is 60%, and the increased duty cycle of the heater is 60×1.1+5×2=76%.

[0039] In implementation, the method of the present invention adjusts the duty cycle of the heater by setting a preset first difference and a preset second difference. Since the heating element may age after long-term use, resulting in reduced or uneven heating efficiency, the temperature difference between different parts of the crystal furnace increases. By increasing the duty cycle of the heater, the aged heating element can accumulate more heat per unit time, thereby improving the overall heating effect, compensating for the heat lost due to aging, and further improving the temperature control stability of the crystal furnace.

[0040] Specifically, based on the growth rate of the crystal in the crystal furnace, determine whether the thermal management in the crystal furnace meets the requirements, that is, determine whether the cause of the temperature control stability of the crystal furnace not meeting the requirements is that the thermal management in the crystal furnace does not meet the requirements, including: comparing the growth rate of the crystal in the crystal furnace with a preset second growth rate; If the growth rate of the crystal in the crystal furnace is greater than the preset second growth rate, determining that the thermal management in the crystal furnace meets the requirements, and determining whether the duty cycle of the heater meets the requirements; If the growth rate of the crystal in the crystal furnace is less than or equal to the preset second growth rate, it is determined that the thermal management in the crystal furnace does not meet the requirements.

[0041] Among them, when the growth rate of the crystal in the crystal furnace is greater than the preset second growth rate, it is determined that the thermal management in the crystal furnace meets the requirements, and it has been determined that the temperature control stability of the crystal furnace does not meet the requirements, then it is necessary to further determine whether the duty cycle of the heater meets the requirements.

[0042] The duty cycle of the heater is the ratio of the power-on time of the heater in a control cycle to the total cycle time. In implementation, whether the duty cycle of the heater meets the requirements is determined based on the comparison between the actual duty cycle of the heater and the predetermined duty cycle threshold. If the actual duty cycle of the heater is less than or equal to the predetermined duty cycle threshold, it is determined that the duty cycle of the heater does not meet the requirements, wherein the predetermined duty cycle threshold is the average value of the duty cycle of the heater monitored within the first three months of the historical cycle of this method.

[0043] If the duty cycle of the heater does not meet the requirements, the duty cycle of the heater is increased; if the duty cycle of the heater meets the requirements, the temperature in the crystal furnace is recollected and the temperature control stability of the crystal furnace is re-evaluated.

[0044] When the crystal growth rate within the crystal furnace is less than or equal to the preset second growth rate, the cause of the crystal furnace's temperature control stability failure is determined to be failure to meet the required thermal management requirements within the crystal furnace. This failure could be caused by failure to meet the required seed crystal rotation speed or failure to meet the required airflow stability within the crystal furnace. The specific cause must then be determined, and this process also determines whether the seed crystal rotation speed needs to be increased.

[0045] Specifically, determining whether it is necessary to increase the rotation speed of the seed crystal includes: Comparing the growth rate of the crystal in the crystal furnace with the preset first growth rate and the preset second growth rate respectively; If the growth rate of the crystal in the crystal furnace is greater than the preset first growth rate and less than or equal to the preset second growth rate, it is determined that the rotation speed of the seed crystal needs to be increased, and the rotation speed of the seed crystal is increased; If the growth rate of the crystal in the crystal furnace is less than or equal to the preset first growth rate, it is determined that there is no need to increase the rotation speed of the seed crystal.

[0046] When the growth rate of the crystal in the crystal furnace is greater than a preset first growth rate and less than or equal to a preset second growth rate, it is determined that the cause of the non-compliance with the thermal management requirements in the crystal furnace is that the rotation speed of the seed crystal does not meet the requirements, and therefore the rotation speed of the seed crystal needs to be increased. When the growth rate of the crystal in the crystal furnace is less than or equal to the preset first growth rate, it can be preliminarily determined that the airflow stability in the crystal furnace does not meet the requirements. Next, it is necessary to make a final determination of whether the airflow stability in the crystal furnace meets the requirements based on the fluctuation amplitude of the pressure in the crystal furnace, that is, to determine whether the cause of the non-compliance with the thermal management requirements in the crystal furnace is that the airflow stability in the crystal furnace does not meet the requirements.

[0047] It can be understood that the preset first growth rate is less than the preset second growth rate, and the three intervals divided by the preset first growth rate and the preset second growth rate correspond to three situations respectively: The first interval is when the crystal growth rate in the crystal furnace is less than or equal to the preset first growth rate. This occurs when the exhaust duct of the crystal furnace is clogged by dust and impurities, resulting in poor exhaust. This causes gas accumulation in the furnace and increased pressure, which in turn causes changes in gas flow and airflow disturbances. In this case, it is necessary to further determine whether the airflow stability in the crystal furnace meets the requirements. The second interval is when the growth rate of the crystal in the crystal furnace is greater than the preset first growth rate and less than or equal to the preset second growth rate. This corresponds to the situation where the furnace body of the crystal furnace may experience structural deformation and cracking due to long-term exposure to high temperature and mechanical stress, causing some heat to be transferred to the outside of the furnace body. In this case, the rotation speed of the seed crystal needs to be adjusted. The third interval is when the growth rate of the crystal in the crystal furnace is greater than the preset second growth rate. The corresponding situation is: it is determined that the thermal management in the crystal furnace meets the requirements. At this time, it is necessary to further determine whether the duty cycle of the heater meets the requirements.

[0048] It is understandable that the preset first growth rate and the preset second growth rate can be set according to actual working conditions. The setting of the preset first growth rate and the preset second growth rate is intended to ensure the control stability and practicality of the crystal furnace. Optionally, the preset first growth rate and the preset second growth rate are determined by evaluating the effects of different growth rates on the generation of crystals, through a limited number of tests, and the determined preset first growth rate and preset second growth rate should satisfy the requirements of being detectable without causing excessive interference to the operation of the crystal furnace. Exemplarily, the preset first growth rate is generally selected in the range of [2mm / h, 4mm / h], and the preset second growth rate is generally selected in the range of [4.5mm / h, 5.5mm / h].

[0049] Preferably, the preferred embodiment of the preset first growth rate is 3 mm / h, and the preferred embodiment of the preset second growth rate is 5 mm / h.

[0050] Specifically, the growth rate of the crystal in the crystal furnace is the ratio of the growth length of the crystal in the crystal furnace per unit time to the duration of the crystal per unit time.

[0051] In implementation, the method of the present invention determines the thermal management in the crystal furnace by setting a preset first growth rate and a preset second growth rate, thereby reducing the impact of the decreased temperature control stability of the crystal furnace due to inaccurate determination of the thermal management in the crystal furnace, and further improving the temperature control stability of the crystal furnace.

[0052] Specifically, the increase in the rotation speed of the seed crystal is proportional to the difference between the growth rate of the crystal in the crystal furnace and the preset first growth rate.

[0053] Specifically, when the difference between the growth rate of the crystal in the crystal furnace and the preset first growth rate is within 2 mm / h, the rotation speed of the seed crystal is increased to 1.2 times the original speed; when the difference between the growth rate of the crystal in the crystal furnace and the preset first growth rate exceeds 2 mm / h, on the basis of increasing to 1.2 times the original speed, the rotation speed of the seed crystal is increased by 3 r / min for every 1 mm / h exceeding. For example, the difference between the growth rate of the crystal in the crystal furnace and the preset first growth rate is 4 mm / h, the current rotation speed of the seed crystal is 15 r / min, and the increased rotation speed of the seed crystal is 15×1.2+3×2=24 r / min.

[0054] In implementation, the method of the present invention adjusts the rotation speed of the seed crystal by setting a preset first growth rate and a preset second growth rate. Since the furnace body of the crystal furnace is subjected to high temperature and mechanical stress for a long time, structural deformation, cracking and other problems may occur, resulting in part of the heat being transferred to the outside of the furnace body. By increasing the rotation speed of the seed crystal, the heat can be more evenly distributed in the furnace, reducing the local low temperature caused by heat transfer to the outside of the furnace body, improving the temperature uniformity of the crystal growth environment, and further improving the temperature control stability of the crystal furnace.

[0055] Specifically, based on the fluctuation amplitude of the pressure in the crystal furnace, it is determined whether the angle of the guide plate in the crystal furnace needs to be increased. In other words, it is determined whether the reason for the failure of the thermal management in the crystal furnace to meet the requirements is that the airflow stability in the crystal furnace does not meet the requirements, including: Compare the fluctuation amplitude of the pressure in the crystal furnace with the preset fluctuation amplitude; If the fluctuation amplitude of the pressure in the crystal furnace is less than or equal to the preset fluctuation amplitude, it is determined that there is no need to increase the angle of the guide plate in the crystal furnace, and whether the rotation speed of the seed crystal meets the requirement; If the fluctuation amplitude of the pressure in the crystal furnace is greater than the preset fluctuation amplitude, it is determined that the angle of the guide plate in the crystal furnace needs to be increased, and the angle of the guide plate in the crystal furnace is increased.

[0056] Among them, when the fluctuation amplitude of the pressure in the crystal furnace is less than or equal to the preset fluctuation amplitude, it is determined that the airflow stability in the crystal furnace meets the requirements. If it has been determined that the thermal management in the crystal furnace does not meet the requirements, then it is necessary to further determine whether the rotation speed of the seed crystal meets the requirements.

[0057] In implementation, whether the rotation speed of the seed crystal meets the requirements is determined based on the comparison between the actual rotation speed of the seed crystal and the predetermined rotation speed threshold. If the actual rotation speed of the seed crystal is less than or equal to the predetermined rotation speed threshold, it is determined that the rotation speed of the seed crystal does not meet the requirements, wherein the predetermined rotation speed threshold is the average value of the rotation speed of the seed crystal monitored within the first three months of the historical period of the method.

[0058] If the rotation speed of the seed crystal does not meet the requirements, the rotation speed of the seed crystal is increased; if the rotation speed of the seed crystal meets the requirements, the growth rate of the crystal in the crystal furnace is re-collected and the thermal management in the crystal furnace is re-evaluated.

[0059] When the fluctuation amplitude of the pressure in the crystal furnace is greater than the preset fluctuation amplitude, it can be determined that the reason why the thermal management in the crystal furnace does not meet the requirements is that the airflow stability in the crystal furnace does not meet the requirements, so it is necessary to increase the angle of the guide plate in the crystal furnace.

[0060] It can be understood that the two intervals divided by the preset fluctuation range correspond to two situations: The first interval is when the fluctuation amplitude of the pressure in the crystal furnace is less than or equal to the preset fluctuation amplitude. This corresponds to the situation where it is determined that the airflow stability in the crystal furnace meets the requirements. In this case, it is necessary to further determine whether the rotation speed of the seed crystal meets the requirements. The second interval is when the fluctuation amplitude of the pressure in the crystal furnace is greater than the preset fluctuation amplitude. The corresponding situation is: the exhaust pipe of the crystal furnace is blocked by dust and impurities, resulting in poor exhaust, gas accumulation in the furnace, and increased pressure, which causes changes in gas flow and airflow disturbances. At this time, the angle of the guide plate needs to be adjusted.

[0061] It is understandable that the preset fluctuation amplitude can be set according to the actual working conditions. The setting of the preset fluctuation amplitude is intended to ensure the control stability and practicality of the crystal furnace. Optionally, the preset fluctuation amplitude is determined by evaluating the operating state of the crystal furnace under different pressures and through a limited number of tests. The determined preset fluctuation amplitude should be able to be detected without causing excessive interference to the operation of the crystal furnace. Exemplarily, the preset fluctuation amplitude is generally selected in the range of [0.4kPa, 0.6kPa].

[0062] Preferably, the preset fluctuation amplitude is 0.5 kPa.

[0063] Specifically, the fluctuation amplitude of the pressure in the crystal furnace is the difference between the maximum pressure and the minimum pressure in the crystal furnace.

[0064] In implementation, the method of the present invention determines the airflow stability in the crystal furnace by setting a preset fluctuation amplitude, thereby reducing the impact of the decrease in the temperature control stability of the crystal furnace due to inaccurate determination of the airflow stability in the crystal furnace, and further improving the temperature control stability of the crystal furnace.

[0065] Specifically, the increase in the angle of the guide plate in the crystal furnace is proportional to the difference between the fluctuation amplitude of the pressure in the crystal furnace and the preset fluctuation amplitude.

[0066] Specifically, when the difference between the fluctuation amplitude of the pressure in the crystal furnace and the preset fluctuation amplitude is within 0.2kPa, the angle of the guide plate in the crystal furnace is increased to 1.1 times the original value; when the difference between the fluctuation amplitude of the pressure in the crystal furnace and the preset fluctuation amplitude exceeds 0.2kPa, on the basis of increasing to 1.1 times the original value, the angle of the guide plate in the crystal furnace is increased by 5° for every 0.1kPa exceeding it. For example, the difference between the fluctuation amplitude of the pressure in the crystal furnace and the preset fluctuation amplitude is 0.4kPa, the current angle of the guide plate in the crystal furnace is 50°, and the increased angle of the guide plate in the crystal furnace is 50×1.1+5×2=65°.

[0067] Specifically, the angle of the guide plate in the crystal furnace is the angle between the guide plate and the axial direction of the crystal furnace.

[0068] During implementation, the method of the present invention adjusts the angle of the guide plate in the crystal furnace by setting a preset fluctuation amplitude. Since the exhaust duct of the crystal furnace is blocked by dust and impurities, resulting in poor exhaust, gas accumulates in the furnace, and the pressure increases, causing changes in gas flow and generating airflow disturbances. By increasing the angle of the guide plate in the crystal furnace, the gas can be more strongly guided in a specific direction, which helps to guide the gas accumulated locally to the exhaust port direction, improve the unevenness of the gas flow, reduce the airflow turbulence caused by gas accumulation, and further improve the temperature control stability of the crystal furnace.

[0069] This embodiment further provides a temperature control system for a crystal furnace, comprising: A crystal growth module, for growing crystals using a crystal furnace, comprising a seed crystal disposed inside the crystal furnace for guiding the growth of the crystal and a guide plate disposed inside the crystal furnace for guiding internal airflow distribution; a detection module connected to the crystal growth module, comprising a temperature sensor disposed inside the crystal furnace for detecting the temperature inside the crystal furnace and a pressure sensor disposed inside the crystal furnace for monitoring the internal pressure of the crystal furnace; A control module is connected to the crystal growth module and the detection module respectively, and is used to determine the duty cycle of the heater according to the maximum temperature difference in the crystal furnace, or to determine the rotation speed of the seed crystal according to the growth rate of the crystal in the crystal furnace, and to determine the angle of the guide plate in the crystal furnace according to the fluctuation amplitude of the pressure in the crystal furnace.

[0070] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A temperature control method for a crystal furnace, characterized in that: include: Setting a target temperature of the crystal furnace, heating the crystal furnace by a heater, and monitoring the internal temperature of the crystal furnace in real time using a temperature sensor; guiding crystal growth through the seed crystal in the crystal furnace, and guiding the airflow distribution in the crystal furnace using a guide plate; Obtaining the temperature in the crystal furnace and calculating the maximum temperature difference in the crystal furnace; determining whether the temperature control stability of the crystal furnace meets the requirements based on the maximum temperature difference in the crystal furnace; If the temperature control stability of the crystal furnace does not meet the requirements, determining whether it is necessary to increase the duty cycle of the heater; If the duty cycle of the heater does not need to be increased, determining whether the thermal management in the crystal furnace meets the requirements based on the growth rate of the crystal in the crystal furnace; If the thermal management in the crystal furnace does not meet the requirements, determining whether it is necessary to increase the rotation speed of the seed crystal; If the rotation speed of the seed crystal does not need to be increased, whether the angle of the guide plate in the crystal furnace needs to be increased is determined based on the fluctuation amplitude of the pressure in the crystal furnace.

2. The temperature control method for a crystal furnace according to claim 1, characterized in that: Determining whether the temperature control stability of the crystal furnace meets the requirements based on the maximum temperature difference in the crystal furnace includes: Comparing the maximum temperature difference in the crystal furnace with a preset first temperature difference; If the maximum temperature difference in the crystal furnace is less than or equal to the preset first difference, it is determined that the temperature control stability of the crystal furnace meets the requirements; If the maximum temperature difference in the crystal furnace is greater than the preset first difference, it is determined that the temperature control stability of the crystal furnace does not meet the requirements.

3. The temperature control method for a crystal furnace according to claim 2, characterized in that: Determine if the heater duty cycle needs to be increased, including: Comparing the maximum temperature difference in the crystal furnace with the preset first difference and the preset second difference respectively; If the maximum temperature difference in the crystal furnace is greater than the preset second difference, determining that the duty cycle of the heater needs to be increased, and increasing the duty cycle of the heater; If the maximum temperature difference in the crystal furnace is greater than the preset first difference and less than or equal to the preset second difference, it is determined that there is no need to increase the duty cycle of the heater.

4. The temperature control method for a crystal furnace according to claim 3, characterized in that: The increase range of the duty cycle of the heater is proportional to the difference between the maximum temperature difference in the crystal furnace and the preset second temperature difference.

5. The temperature control method for a crystal furnace according to claim 3, characterized in that: Determine whether the thermal management in the crystal furnace meets the requirements based on the crystal growth rate in the crystal furnace, including: comparing the growth rate of the crystal in the crystal furnace with a preset second growth rate; If the growth rate of the crystal in the crystal furnace is greater than the preset second growth rate, determining that the thermal management in the crystal furnace meets the requirements, and determining whether the duty cycle of the heater meets the requirements; If the growth rate of the crystal in the crystal furnace is less than or equal to the preset second growth rate, it is determined that the thermal management in the crystal furnace does not meet the requirements.

6. The temperature control method for a crystal furnace according to claim 5, characterized in that: Determine if the seed crystal rotation speed needs to be increased, including: Comparing the growth rate of the crystal in the crystal furnace with the preset first growth rate and the preset second growth rate respectively; If the growth rate of the crystal in the crystal furnace is greater than the preset first growth rate and less than or equal to the preset second growth rate, it is determined that the rotation speed of the seed crystal needs to be increased, and the rotation speed of the seed crystal is increased; If the growth rate of the crystal in the crystal furnace is less than or equal to the preset first growth rate, it is determined that there is no need to increase the rotation speed of the seed crystal.

7. The temperature control method for a crystal furnace according to claim 6, characterized in that: The increase in the rotation speed of the seed crystal is proportional to the difference between the growth rate of the crystal in the crystal furnace and the preset first growth rate.

8. The temperature control method for a crystal furnace according to claim 7, characterized in that: Determine whether to increase the angle of the guide plate in the crystal furnace based on the fluctuation amplitude of the pressure in the crystal furnace, including: Compare the fluctuation amplitude of the pressure in the crystal furnace with the preset fluctuation amplitude; If the fluctuation amplitude of the pressure in the crystal furnace is less than or equal to the preset fluctuation amplitude, it is determined that there is no need to increase the angle of the guide plate in the crystal furnace, and whether the rotation speed of the seed crystal meets the requirement; If the fluctuation amplitude of the pressure in the crystal furnace is greater than the preset fluctuation amplitude, it is determined that the angle of the guide plate in the crystal furnace needs to be increased, and the angle of the guide plate in the crystal furnace is increased.

9. The temperature control method for a crystal furnace according to claim 8, characterized in that: The increase range of the angle of the guide plate in the crystal furnace is proportional to the difference between the fluctuation range of the pressure in the crystal furnace and the preset fluctuation range.

10. A temperature control system using the temperature control method for a crystal furnace according to any one of claims 1 to 9, characterized in that: include: A crystal growth module, for growing crystals using a crystal furnace, comprising a seed crystal disposed inside the crystal furnace for guiding the growth of the crystal and a guide plate disposed inside the crystal furnace for guiding internal airflow distribution; a detection module connected to the crystal growth module, comprising a temperature sensor disposed inside the crystal furnace for detecting the temperature inside the crystal furnace and a pressure sensor disposed inside the crystal furnace for monitoring the internal pressure of the crystal furnace; A control module is connected to the crystal growth module and the detection module respectively, and is used to determine the duty cycle of the heater according to the maximum temperature difference in the crystal furnace, or to determine the rotation speed of the seed crystal according to the growth rate of the crystal in the crystal furnace, and to determine the angle of the guide plate in the crystal furnace according to the fluctuation amplitude of the pressure in the crystal furnace.

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