Single crystal furnace and cleaning method and device for exhaust pipeline of single crystal furnace and medium

Abstract

The present disclosure provides a single crystal furnace, a cleaning method and device of an exhaust pipeline of a single crystal furnace, and a medium. The cleaning method comprises: determining a current crystal growth stage of the single crystal furnace; obtaining a current opening value of a throttle valve arranged on an exhaust pipeline of the single crystal furnace; when the current opening value is greater than or equal to a first opening threshold value corresponding to the current crystal growth stage, generating a trigger signal and transmitting the trigger signal to a cleaning executor arranged in the exhaust pipeline, so that the cleaning executor performs a cleaning operation on the exhaust pipeline.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing technology, and in particular to a method, apparatus and medium for cleaning a single crystal furnace and its exhaust pipe. Background Technology

[0002] Currently, the Czochralski (CZ) method is the primary method for preparing large-size, high-quality single-crystal silicon. In the process of pulling single-crystal silicon rods using the Czochralski method (also known as crystal pulling), high-purity polycrystalline silicon raw materials are placed in a quartz crucible and melted in a vacuum furnace. To prevent oxidation of the silicon melt and control impurity volatilization, a vacuum environment needs to be maintained inside the furnace, for example, at 10-30 Torr, and argon gas is introduced as a protective gas.

[0003] In a high-temperature molten state (approximately 1420°C), molten silicon (Si) reacts chemically with a quartz crucible (SiO2) to produce gaseous silicon monoxide (SiO). This gaseous SiO is then discharged from the single crystal furnace via the exhaust pipe of the argon gas flow.

[0004] However, the exhaust duct is usually located outside the hot zone of the furnace, where the temperature drops sharply. When the high-temperature SiO gas enters the low-temperature exhaust duct, especially at bends, bellows, or valves, it condenses from a gaseous state into a solid and deposits on the inner wall of the exhaust duct. As the crystal pulling process continues, for example, for tens of hours to several days, the solid material deposited on the inner wall of the exhaust duct gradually thickens, leading to a reduction in the effective flow cross-sectional area of ​​the exhaust duct and eventually blockage. Summary of the Invention

[0005] This disclosure provides a method, apparatus, and medium for cleaning a single crystal furnace and its exhaust pipe; it can promptly identify the blockage trend of the exhaust pipe and clean the exhaust pipe before the vacuum level becomes abnormal, thus avoiding the impact of severe blockage on the quality of the crystal rod, improving production efficiency, and reducing production costs.

[0006] The technical solution disclosed herein is implemented as follows:

[0007] In a first aspect, this disclosure provides a method for cleaning the exhaust pipe of a single crystal furnace, comprising: Determine the current crystal growth stage of the single crystal furnace; Obtain the current opening value of the throttle valve set on the exhaust pipe of the single crystal furnace; When the current opening value is greater than or equal to the first opening threshold corresponding to the current crystal growth stage, a trigger signal is generated and transmitted to the cleaning actuator set in the exhaust pipe, so that the cleaning actuator can perform a cleaning operation on the exhaust pipe.

[0008] In some examples, the first aperture threshold is obtained from the baseline aperture value and tolerance increment corresponding to the current crystal growth stage.

[0009] In some examples, the method also includes: When the current opening value is less than the second opening threshold corresponding to the current crystal growth stage, a stop signal is generated and transmitted to the cleaning actuator so that the cleaning actuator stops cleaning the exhaust pipe. The second opening threshold is less than the first opening threshold.

[0010] In some examples, the second aperture threshold is obtained from the baseline aperture value corresponding to the current crystal growth stage and the hysteresis increment.

[0011] In some examples, the baseline opening value is the arithmetic mean of multiple historical opening values ​​of the throttle valve during a period when the exhaust duct is clean and the single crystal furnace is operating stably at the current crystal growth stage.

[0012] In some examples, the tolerance increment is the maximum flow rate attenuation calculated based on a vacuum flow conduction model of a single-crystal furnace, which characterizes the mapping relationship between the flow rate attenuation and the throttle valve opening increment.

[0013] In some examples, the method also includes: When a signal is detected indicating a switch from the current crystal growth stage to the next crystal growth stage, the reference aperture value, tolerance increment, and hysteresis increment corresponding to the next crystal growth stage are obtained.

[0014] In some examples, the crystal growth process stages include any one of the following: seeding stage, shoulder formation stage, constant diameter stage, and finishing stage.

[0015] Secondly, this disclosure provides a cleaning device for the exhaust pipe of a single crystal furnace, comprising: An opening sensor connected to a throttle valve installed on the exhaust pipe of the single crystal furnace is used to detect the current opening value of the throttle valve installed on the exhaust pipe of the single crystal furnace. A cleaning actuator installed inside the exhaust pipe is used to remove deposits from the inner wall of the exhaust pipe. A controller, which is communicatively connected to an opening sensor and a cleaning actuator, includes a processor and a memory, the memory storing a computer program, the processor executing the computer program to implement a cleaning method for the exhaust duct of a single crystal furnace as described in the first aspect and its examples.

[0016] Thirdly, this disclosure provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the cleaning method for the exhaust pipe of a single crystal furnace as described in the first aspect and its examples.

[0017] Fourthly, this disclosure provides a single crystal furnace, comprising: A furnace body, which defines a chamber and has an air outlet communicating with the chamber. The exhaust pipe connected to the air outlet; A throttle valve installed on the exhaust pipe; And a cleaning device for the exhaust duct of the single crystal furnace as described in the second aspect.

[0018] This disclosure provides a method, apparatus, and medium for cleaning a single crystal furnace and its exhaust pipe. The degree of blockage in the exhaust pipe is characterized by the opening value of a throttle valve. The blockage is then compared with a first opening threshold corresponding to the current crystal growth stage to determine whether cleaning is necessary. When cleaning is required, a cleaning actuator is triggered to perform the cleaning operation. Therefore, this technical solution can promptly identify the blockage trend in the exhaust pipe and clean it before vacuum abnormalities occur, avoiding impact on crystal rod quality due to severe blockage, improving production efficiency, and reducing production costs. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a single crystal furnace provided in this disclosure.

[0020] Figure 2 This is a schematic diagram of the composition of a cleaning actuator provided in this disclosure.

[0021] Figure 3 This is a schematic diagram of the composition of a controller provided in this disclosure.

[0022] Figure 4 This is a schematic diagram of a cleaning method for the exhaust pipe of a single crystal furnace provided in this disclosure.

[0023] Figure 5 This is a schematic diagram of the opening value over time provided in this disclosure.

[0024] Figure 6 In the diagram, A represents the mapping relationship between the opening degree and flow conductance of the throttle valve provided in this disclosure. Figure 6 B in the diagram represents the correspondence between the opening increment and the flow attenuation rate provided in this disclosure. Detailed Implementation

[0025] The technical solutions in this disclosure will now be clearly and completely described with reference to the accompanying drawings.

[0026] Figure 1This is a schematic diagram of a single crystal furnace provided in this disclosure. The single crystal furnace prepares single crystal silicon rods using the Czochralski method. The single crystal furnace 100 includes a furnace body 10, which defines a growth chamber 11. At the center of the growth chamber 11, a quartz crucible 12 for holding molten silicon 13 is disposed. The outer periphery of the quartz crucible 12 is surrounded by a graphite heater 14, which is powered by a DC power supply to provide the heat required to melt the polycrystalline silicon. The crucible 12 is typically supported on a rotatable and liftable crucible shaft 121.

[0027] At the top of the furnace body 10, a crystal pulling mechanism 15 is provided for suspending the seed crystal 16 and controlling its rotation and lifting to pull and grow a single crystal silicon rod 17 from the silicon melt 13. An air inlet 18 is provided above the furnace body 10 for introducing high-purity argon (Ar). The argon forms a protective gas flow inside the furnace, carrying away the SiO gas volatilized from the melt surface, and is discharged through the air outlet 19 located at the bottom of the furnace body 10.

[0028] Connected to the outlet 19 is an exhaust pipe 20. This pipe is typically made of stainless steel and includes elbows, corrugated sections, and straight sections. The end of the exhaust pipe 20 is connected to a vacuum pump 30. The vacuum pump 30 provides a stable pumping capacity to ensure the vacuum level within the growth chamber 11.

[0029] In this disclosure, a throttle valve 40 is disposed on the exhaust pipe 20, located between the exhaust port 19 and the vacuum pump 30. The throttle valve 40 is typically a butterfly valve or a swing valve, equipped with a servo motor driver (not shown), capable of adjusting the opening degree between 0° (fully closed) and 90° (fully open) according to a control signal to maintain the target vacuum level within the growth chamber 11.

[0030] Since the exhaust duct is typically located outside the thermal zone of the furnace body 10, during the process of gaseous SiO being expelled from the growth chamber 11 with the argon gas flow, when the high-temperature SiO gas enters the low-temperature exhaust duct 20, especially at bends, bellows, or valves, it condenses from a gaseous state into a solid state and deposits on the inner wall of the exhaust duct. The thickening of this deposit reduces the effective flow cross-sectional area of ​​the exhaust duct 20, i.e., it becomes blocked, thereby increasing the flow resistance (also known as flow resistance) and reducing the flow conductivity within the exhaust duct 20. To maintain the required vacuum level within the growth chamber 11, such as 10⁻³⁰ Torr, the vacuum pump needs to operate continuously, and the opening of the throttle valve must also be continuously increased to counteract the flow resistance.

[0031] exist Figure 1 The present disclosure also includes a cleaning device 300 for the exhaust pipe of a single crystal furnace, the cleaning device 300 comprising: An opening sensor 310 connected to a throttle valve 40 disposed on an exhaust pipe 20 is used to detect the current opening value of the throttle valve 40.

[0032] A cleaning actuator 320, disposed within the exhaust duct 20, is used to remove deposits from the inner wall of the exhaust duct. In this disclosure, the cleaning actuator 320 is disposed on the inner wall of the exhaust duct 20 and installed upstream or downstream of the throttle valve 40 at a clog-prone section for removing deposits from the inner wall. In this disclosure, as... Figure 1 As shown, the cleaning actuator 320 is installed upstream of the throttle valve 40, i.e., on the side close to the furnace body 10. This is because SiO deposits are mainly concentrated at the front bend of the exhaust pipe 20 where the temperature drops sharply. If deposits accumulate here, it will increase the flow resistance between the furnace body 10 and the throttle valve 40.

[0033] like Figure 2 As shown, the cleaning actuator 320 includes a first scraper 321 near the furnace body 10, a second scraper 322 away from the furnace body 10, a connector 323 for connecting the first scraper 321 and the second scraper 322, and a rotating shaft 324 connected to the connector 323. The first scraper 321 and the second scraper 322 are in contact with the inner wall of the exhaust pipe 20. When the rotating shaft 324 rotates, it drives the first scraper 321 and the second scraper 322 to rotate to scrape off deposits.

[0034] exist Figure 1 The cleaning device 300 also includes a controller 330 that is communicatively connected to the opening sensor 310 and the cleaning actuator 320. The controller 330 receives the current opening value transmitted by the opening sensor 310 and outputs a trigger signal or a stop signal to the cleaning actuator 320, so that the cleaning actuator 320 starts or stops cleaning the deposits on the inner wall of the exhaust pipe 20. For example, the controller 330 sends a trigger signal to a drive motor (not shown) that drives the shaft 324 of the cleaning actuator 320 to rotate, so that the drive motor drives the shaft 324 to rotate, or sends a stop signal to the drive motor to stop the shaft 324 from rotating.

[0035] like Figure 2 As shown, the controller 330 includes at least one processor 332, a memory 334, and a communication connector 336, wherein the communication connector 336 enables the controller 330 to communicate with the opening sensor 310 and the cleaning actuator 320, respectively.

[0036] In this disclosure, memory 334 may include a mass storage device, a removable storage device, a volatile read-write memory, a read-only memory (ROM), or a combination thereof. Memory 334 may store data, instructions, and / or any other information. For example, memory 334 may store the current aperture value transmitted by aperture sensor 310, or information about the crystal growth stage transmitted by the control system (not shown) of single crystal furnace 100. Furthermore, memory 334 may store data and / or instructions executable by processor 332, which, when executed by processor 332, enable the cleaning method for the single crystal furnace exhaust pipe proposed in this disclosure.

[0037] In related solutions, a pressure sensor is typically used to monitor the actual vacuum level within the growth chamber 11 and compare it with a set value to determine if blockage has occurred, and to trigger an alarm when blockage is detected. However, since adjusting the opening of the throttle valve 40 can maintain the flow conduction within the exhaust pipe 20 and the required vacuum level within the growth chamber 11 even in the case of minor blockage, if blockage is determined solely based on the actual vacuum level and cleaning is performed, the blockage in the exhaust pipe 20 is already quite severe. In other words, the method of determining blockage based on vacuum level in related solutions has a lag. This lag forces the crystal pulling process to be interrupted when the blockage is very severe, resulting in the scrapping of the entire crystal rod and increased production costs. In addition, although the pressure within the growth chamber 11 remains stable before the alarm occurs, the throttle valve opening is already close to its maximum value, reducing the ability to regulate pressure fluctuations. In this situation, even small pressure fluctuations may cause melt oscillations, inducing crystal dislocations or twinning. Moreover, cleaning the pipe after severe blockage is extremely difficult, often requiring shutdown and disassembly for cleaning, affecting production efficiency.

[0038] To identify blockages earlier and address them promptly compared to existing solutions, this disclosure uses the opening value of the throttle valve 40 as a control variable to overcome the flow resistance in the exhaust pipe 20 and maintain the target vacuum level within the growth chamber 11. This flow resistance primarily originates from pipe blockage; therefore, this disclosure utilizes the opening value of the throttle valve 40 to characterize the degree of blockage and thereby determine whether the exhaust pipe needs cleaning. Figure 4 This disclosure provides a method for cleaning the exhaust duct of a single crystal furnace. The cleaning method comprises... Figure 1 or Figure 3 The controller 330 shown executes the commands, or the processor 332 of the controller 330 executes them.

[0039] See Figure 4 In step S410, the current crystal growth stage of the single crystal furnace is determined.

[0040] Monocrystalline silicon growth is a staged growth process. During the pulling of a monocrystalline silicon rod, the crystal growth stages can be divided into four phases: crystal introduction, shoulder formation, constant diameter formation, and finishing. Specifically, the processor 332 can obtain indication information from the control system of the monocrystalline furnace 100 via the communication connector 336 to determine the current crystal growth stage. Furthermore, the processor 332 can also determine the current crystal growth stage by analyzing the power of the heater 14 of the monocrystalline furnace and the rate at which the crystal pulling mechanism 15 lifts the crystal rod; these details are not elaborated upon in this disclosure.

[0041] In step S420, the current opening value of the throttle valve installed on the exhaust pipe of the single crystal furnace is obtained.

[0042] In this disclosure, processor 332 is connected to opening sensor 310 via communication connector 336. Processor 332 reads the current opening value of throttle valve 40 at a preset sampling frequency, for example, 1 Hz. To eliminate signal noise, the processor 332 can perform sliding filtering on the read current opening value.

[0043] In step S430, when the current opening value is greater than or equal to the first opening threshold corresponding to the current crystal growth stage, a trigger signal is generated and transmitted to the cleaning actuator set in the exhaust pipe so that the cleaning actuator can perform a cleaning operation on the exhaust pipe.

[0044] Specifically, the opening value of the throttle valve 40 can be used to characterize the degree of blockage in the exhaust pipe 40. For example, this disclosure sets the throttle valve opening value to a reference opening value when the exhaust pipe 20 is in an ideal unblocked state. Then when the current opening value of throttle valve 40 is At that time, the degree of blockage in the exhaust pipe 40 can be determined by... Characterize it.

[0045] Based on this, the present disclosure allows for setting tolerance increments for the opening value. This tolerance increment and the baseline opening value together indicate that the blockage of the exhaust pipe 40 has reached a level requiring cleaning. Specifically, the first opening threshold is set as follows: When the current opening value of throttle valve 40 When the opening value is greater than or equal to the first opening threshold, it indicates that the blockage of the exhaust pipe 40 has reached a level that requires cleaning. At this time, the processor 332 sends a trigger signal to the drive motor of the cleaning actuator 320 to trigger the drive motor to drive the rotating shaft 324 to rotate, and drive the first scraper 321 and the second scraper 322 to scrape off the deposits deposited on the inner wall of the exhaust pipe, thereby completing the cleaning operation of the exhaust pipe 40.

[0046] Compared to the vacuum degree method used in related solutions to determine blockage, the technical solution disclosed in this paper can use the increase in the opening value to inversely determine the increase in the flow resistance and decrease in the flow conductance of the exhaust pipe when the vacuum degree has not become abnormal, and clean it accordingly, thus avoiding crystal growth accidents caused by severe blockage.

[0047] In some examples, the crystal growth stage can be divided into four stages: crystal introduction, shoulder formation, constant diameter formation, and tailing. Each stage has vastly different requirements for the stability of the crystal growth environment. Therefore, for each stage of crystal growth, this disclosure sets a corresponding reference aperture value and tolerance increment for each stage.

[0048] pass Figure 4 The technical solution described herein uses the opening value of a throttle valve to characterize the degree of blockage in the exhaust pipe. It then uses the current opening value of the throttle valve and the first opening threshold corresponding to the current crystal growth stage to determine whether the blockage in the exhaust pipe has reached a level requiring cleaning. When cleaning is determined to be necessary, a cleaning actuator is triggered to perform a cleaning operation on the exhaust pipe. Therefore, the technical solution disclosed herein can promptly identify the blockage trend in the exhaust pipe and perform cleaning before the vacuum level becomes abnormal, avoiding the impact on the quality of the crystal rod due to severe blockage, improving production efficiency, and reducing production costs.

[0049] In some examples, Figure 4 The cleaning method shown may further include: when the current opening value is less than the second opening threshold corresponding to the current crystal growth stage, generating a stop signal and transmitting it to the cleaning actuator so that the cleaning actuator stops cleaning the exhaust pipe.

[0050] Specifically, after the cleaning actuator 320 is triggered and cleans the inner wall of the exhaust pipe 20, the flow area of ​​the exhaust pipe gradually recovers as the scraper removes deposits, and the flow resistance within the exhaust pipe 20 continuously decreases. To prevent the furnace pressure from dropping too low and maintain the vacuum level within the growth chamber 11, the opening value of the throttle valve 40 also continuously decreases. The technical solution of this disclosure sets a second opening threshold value lower than the first opening threshold value. The cleaning operation on the exhaust pipe only stops when the opening value of the throttle valve 40 continuously decreases to below the second opening threshold value.

[0051] Understandably, if the threshold values ​​for triggering and stopping the cleaning operation are set to be the same or close, the opening value of the throttle valve will fluctuate slightly around these threshold values. This slight fluctuation will lead to frequent start-stop of the cleaning actuator, accelerating its mechanical wear and reducing its service life. However, by using a second opening threshold, which is lower than the first opening threshold, as the threshold for stopping the cleaning operation, a hysteresis range is created between the first and second opening thresholds. This not only avoids frequent start-stop of the cleaning actuator but also extends its working time, ensuring smoother exhaust flow.

[0052] For this example, this disclosure can set a hysteresis increment with respect to the opening value. , The hysteresis increment and the baseline opening value together indicate that the exhaust pipe 40 is clean and unobstructed, and the cleaning operation can be stopped. Specifically, the second opening threshold is set to... When the current opening value of throttle valve 40 When the opening is less than the second opening threshold, it indicates that the exhaust pipe 40 has been cleaned and is unobstructed. At this time, the processor 332 will send a stop signal to the drive motor of the cleaning actuator 320 to trigger the drive motor to drive the rotating shaft 324 to stop rotating, and also cause the first scraper 321 and the second scraper 322 to stop rotating, thus stopping the cleaning operation on the exhaust pipe.

[0053] Therefore, combining the first opening threshold and the second opening threshold, Figure 5 A schematic diagram of the opening value over time provided in this disclosure is shown. Figure 5 In the diagram, the horizontal axis represents time in hours, and the vertical axis represents the opening value in percentages (%). From... Figure 5 As can be seen, as the opening value continuously increases, it reaches the first opening threshold K_high at time T2, triggering the cleaning actuator 320 to perform a cleaning operation on the exhaust pipe. Subsequently, the opening value slightly increases at time T3, then gradually decreases as the cleaning operation continues, until it decreases to below the second opening threshold K_low at time T4, at which point the cleaning operation stops. Then, deposits continuously accumulate on the inner wall of the exhaust pipe, and the opening value continues to increase, repeating this cycle.

[0054] for Figure 4The illustrated technical solution, exemplarily, includes four stages in the crystal growth process: seeding, shoulder formation, equal diameter formation, and termination. The seeding stage is the first stage of crystal growth, and the ingot pulling process has just begun. Therefore, the blockage of the venting pipe 20 should be minimal, or even nonexistent. Consequently, the baseline aperture value corresponding to the seeding stage is the lowest among the four stages. Furthermore, during the seeding stage, since the seed crystal 16 has just contacted the surface of the molten silicon 13, it is extremely sensitive to the growth environment; even slight vibrations can cause lattice misalignment. In this situation, unless the blockage is severe, cleaning operations should be avoided as much as possible during this stage. Based on this, the tolerance increment of the seeding stage... It can be set to a larger value, and the hysteresis increment The value is set to a smaller value. This not only avoids triggering the cleaning operation at this stage but also ensures thorough cleaning.

[0055] For example, the shoulder formation stage is the second stage of crystal growth. As the crystal pulling process proceeds, even without blockage, increased filter resistance in the exhaust pipe or decreased vacuum pump efficiency can cause the reference opening value of the throttle valve corresponding to the shoulder formation stage to be greater than that corresponding to the crystal pulling stage. Furthermore, during the shoulder formation stage, the crystal diameter rapidly increases, the thermal field changes significantly, and the tolerance for flow field disturbances is high, allowing for larger opening fluctuations. In this case, the tolerance increment during the shoulder formation stage… It can be set to the largest tolerance increment among the four stages, and the difference between the tolerance increment and the hysteresis increment can be set to the largest among the four stages.

[0056] For example, the constant diameter stage is the third stage of crystal growth, and the reference aperture value corresponding to this stage is greater than that corresponding to the shoulder formation stage. Moreover, the constant diameter stage is the core stage of the crystal pulling process, requiring extremely high vacuum stability. In this case, the tolerance increment and hysteresis increment of the constant diameter stage are the lowest among the four stages. Thus, a cleaning operation is triggered when the flow resistance increases only slightly, so as to control the flow conductance fluctuations in this core stage within an extremely narrow range, thereby ensuring the quality and high uniformity of the crystal rod during the critical growth stage.

[0057] For example, the final stage is the fourth and last stage of crystal growth, and the reference aperture value corresponding to this stage is the maximum value among the four stages. Moreover, this stage also indicates that a complete crystal pulling process is about to end. In order to prevent the pipeline from being completely blocked and affecting the start-up of the single crystal furnace in the next crystal pulling process, the tolerance increment corresponding to this stage can be set to a larger value, and the difference between the tolerance increment and the hysteresis increment can be increased to prevent complete blockage from affecting the next furnace start-up.

[0058] Based on the above examples, this disclosure sets corresponding parameter sets for each stage. Each parameter set includes the reference aperture value, tolerance increment, and hysteresis increment corresponding to that stage. These parameter sets can be stored in the memory 334. After the processor 332 learns the current crystal growth stage from the control system of the single crystal furnace 100, it can calculate the first aperture threshold and the second aperture threshold by calling the parameter set corresponding to that stage in the memory 334, as shown in Table 1.

[0059] Table 1

[0060] In this disclosure, since an ideal blockage-free state cannot be achieved in engineering, the processor 332 can collect several historical opening values ​​of the throttle valve during a period when the exhaust pipe is clean and the single crystal furnace is operating in a stable crystal growth process stage, and the arithmetic mean of these historical opening values ​​is determined as the reference opening value corresponding to the crystal growth process stage.

[0061] Specifically, cleanliness is to ensure The basis for accuracy. Specifically, the technical solution disclosed herein calculates the current flow through processor 332. With theoretical clean flow conduction The deviation. If the percentage of the deviation meets the following... If the condition is clear, then it is considered to be in a clean state. It is set to a minimum value.

[0062] Furthermore, the stabilization period is to avoid the impact of transient changes during the crystal pulling process on... Interference in data acquisition. Specifically, the processor 332 simultaneously monitors thermal stability indicators, pressure stability indicators, and mechanical stability indicators. For example, the thermal stability indicator could be the fluctuation range of the temperature sensor. If the pressure is below a set threshold, the pressure stability indicator can be the pressure in the growth chamber. standard deviation If the values ​​are below a preset threshold, the mechanical stability indicators can be that the crystal lifting speed and crucible rotation speed remain constant. Historical aperture values ​​will only be collected after these indicators have been consistently met and exceeded for a preset minimum duration.

[0063] In this disclosure, the tolerance increment is the maximum flow rate attenuation rate calculated based on a vacuum flow conduction model of a single crystal furnace, which characterizes the mapping relationship between the flow rate attenuation rate and the throttle valve opening increment.

[0064] Specifically, flow guidance It is a parameter that measures the ability of fluid to pass through a pipe.

[0065] For tolerance increment Specifically, the determination of the mass flow rate of gas passing through the single crystal furnace under a stable crystal pulling process. It can be considered constant. According to the flow equation in a vacuum, the low-pressure environment of a single crystal furnace approximately conforms to a viscous flow state, i.e., the following relationship exists between flow rate, pressure, and conductance:

[0066] in, The average pressure in the pipeline. This refers to the flow conductance of the pipeline. A throttle valve can be considered an adjustable flow conductance element; therefore, the total flow conductance of the entire flow path from the furnace body to the vacuum pump... It can be regarded as a pipe flow guide With throttle valve flow guide The cascade result. Under clean conditions, It is very large, and the total conductance is mainly composed of Decision. When a blockage occurs in the pipe, A significant decrease has become the dominant factor.

[0067] Set the total conductivity of the pipeline under clean conditions as follows: The total conductance after blockage is To maintain the same furnace pressure, i.e., the same pumping efficiency, the pumping speed at the vacuum pump inlet needs to remain constant. This means that the flow rate through the system... It must remain constant. However, the flow rate attenuation... It is an indicator used to measure the degree of congestion, defined as the potential flow loss caused by congestion, and calculated using the following formula: Therefore, a maximum allowable flow attenuation rate (For example, 10%), which corresponds to a minimum allowable total conductance. ,and .

[0068] The opening degree K of the throttle valve and its flow conductance There is an inherent mapping relationship. ,like Figure 6 As shown in Figure A, this relationship is provided by the valve manufacturer or can be calibrated experimentally. Under clean conditions, to achieve the target vacuum level, the throttle valve opening is set to... Corresponding flow guide At this point, because the flow conductance of the clean pipeline is much greater than that of the valve, the total flow conductance... .

[0069] When the pipe is blocked Descending to At that time, in order to maintain total flow Not less than It is necessary to increase the throttle valve opening to improve According to the series conductance formula:

[0070] in, .

[0071] By solving the above equations, the new valve conductance required to compensate for conductance loss under the current blockage condition can be obtained. Then, by reverse-checking the flow conductance-opening mapping relationship of the valve... This allows for the final determination of the required tolerance increment. Tolerance increment With flow attenuation rate The correspondence between them is as follows: Figure 6 As shown in Figure B.

[0072] In some examples, Figure 4 The technical solution shown also includes: when a signal is detected that the crystal growth stage is switching to the next crystal growth stage, the reference aperture value, tolerance increment and hysteresis increment corresponding to the next crystal growth stage are obtained.

[0073] Specifically, when the processor 332 receives the instruction information transmitted by the control system of the single crystal furnace 100 and learns that it is entering the next crystal growth stage, such as from the current shoulder-forming stage to the constant diameter stage, the processor 332 can call the parameter group stored in the memory 334 to learn the reference aperture value, tolerance increment and hysteresis increment corresponding to the constant diameter stage, and calculate the first aperture threshold and the second aperture threshold corresponding to the constant diameter stage, so as to make real-time determination of the aperture value in the constant diameter stage.

[0074] This disclosure also provides a computer-readable storage medium storing at least one instruction that is executed by a processor to implement the cleaning method for the exhaust pipe of a single crystal furnace as described in the various embodiments above.

[0075] This disclosure also provides a computer program product including computer instructions stored in a computer-readable storage medium; a processor of a computing device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computing device to perform the cleaning method for the exhaust pipe of the single crystal furnace described in the above embodiments.

[0076] Those skilled in the art will recognize that the functions described in this disclosure in one or more of the examples above can be implemented using hardware, software, firmware, or any combination thereof. When implemented in software, these functions can be stored in a computer-readable medium or transmitted as one or more instructions or code on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein communication media include any medium that facilitates the transfer of a computer program from one place to another. Storage media can be any available medium accessible to a general-purpose or special-purpose computer.

[0077] It should be noted that the technical solutions described in this disclosure can be combined arbitrarily as long as they do not conflict.

[0078] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A method for cleaning the exhaust pipe of a single crystal furnace, characterized in that, The cleaning method includes: Determine the current crystal growth stage of the single crystal furnace; Obtain the current opening value of the throttle valve set on the exhaust pipe of the single crystal furnace; When the current opening value is greater than or equal to the first opening threshold corresponding to the current crystal growth stage, a trigger signal is generated and transmitted to the cleaning actuator installed in the exhaust pipe, so that the cleaning actuator performs a cleaning operation on the exhaust pipe; the first opening threshold is obtained from the reference opening value and tolerance increment corresponding to the current crystal growth stage.

2. The cleaning method according to claim 1, characterized in that, The method further includes: When the current opening value is less than the second opening threshold corresponding to the current crystal growth stage, a stop signal is generated and transmitted to the cleaning actuator so that the cleaning actuator stops cleaning the exhaust pipe. The second opening threshold is less than the first opening threshold. The second opening threshold is obtained by the reference opening value corresponding to the current crystal growth stage and the hysteresis increment.

3. The method according to claim 1, characterized in that, The reference opening value is the arithmetic mean of multiple historical opening values ​​of the throttle valve during a period when the exhaust pipe is clean and the single crystal furnace is operating at a stable stage of the current crystal growth.

4. The cleaning method according to claim 1, characterized in that, The tolerance increment is the maximum flow rate attenuation rate calculated based on the vacuum flow conduction model of the single crystal furnace. The vacuum flow conduction model characterizes the mapping relationship between the flow rate attenuation rate and the throttle valve opening increment.

5. The cleaning method according to claim 1, characterized in that, The method further includes: When a signal is detected that the crystal growth stage is switching to the next crystal growth stage, the reference aperture value, tolerance increment, and hysteresis increment corresponding to the next crystal growth stage are obtained.

6. The cleaning method according to claim 1, characterized in that, Crystal growth stages include any one of the following: seeding stage, shoulder formation stage, constant diameter stage, and termination stage.

7. A cleaning device for the exhaust pipe of a single crystal furnace, characterized in that, The cleaning device includes: An opening sensor connected to a throttle valve installed on the exhaust pipe of the single crystal furnace is used to detect the current opening value of the throttle valve installed on the exhaust pipe of the single crystal furnace. A cleaning actuator installed inside the exhaust pipe is used to remove deposits from the inner wall of the exhaust pipe. A controller communicatively connected to the opening sensor and the cleaning actuator, the controller including a processor and a memory, the memory storing a computer program, the processor executing the computer program to implement the cleaning method for the exhaust pipe of the single crystal furnace as described in any one of claims 1 to 6.

8. The cleaning device according to claim 7, characterized in that, The cleaning actuator includes a first scraper close to the furnace body of the single crystal furnace, a second scraper away from the furnace body, a connector for connecting the first scraper and the second scraper, and a rotating shaft connected to the connector; the first scraper and the second scraper are in contact with the inner wall of the exhaust pipe, and when the rotating shaft rotates, the rotating shaft drives the first scraper and the second scraper to rotate to scrape off the deposits.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements a method for cleaning the exhaust pipe of a single crystal furnace as described in any one of claims 1 to 6.

10. A single crystal furnace, characterized in that, The single crystal furnace includes: A furnace body, wherein a chamber is defined within the furnace body, and an air outlet communicating with the chamber is provided on the furnace body; The exhaust pipe connected to the air outlet; A throttle valve is installed on the exhaust pipe; And a cleaning device for the exhaust pipe of a single crystal furnace as described in claim 7 or 8.

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