A temperature closed-loop control method based on a mechanism for cleaning temperature measuring windows during silicon carbide growth

Abstract

The present invention belongs to the field of crystal growth technology, and specifically relates to a mechanism for cleaning a temperature measuring window during silicon carbide growth and a temperature closed-loop control method. The mechanism for cleaning the temperature measuring window during silicon carbide growth comprises a vacuum chamber, a water-cooled flange seat is installed above the vacuum chamber, and is characterized in that a support seat is installed above the vacuum chamber, and the support seat is located above the water-cooled flange seat, and a thermometer is installed above the support seat. The present invention effectively solves the problem of an infrared thermometer being unable to effectively measure temperature due to a blocked temperature measuring window, resulting in an inability to achieve closed-loop temperature control. When a temperature anomaly is detected in a specific temperature range model, the temperature measuring hole is determined to be blocked, and the temperature measuring window cleaning mechanism is driven by a PLC to clean the temperature measuring window, thereby ensuring the accuracy of the temperature value measured by the infrared thermometer and achieving closed-loop temperature control.

Description

Technical Field

[0001] The present invention belongs to the technical field of crystal growth, and in particular relates to a temperature closed-loop control method based on a mechanism for cleaning a temperature measuring window during the growth process of silicon carbide. Background Art

[0002] During the PVT process for preparing silicon carbide single crystals, infrared temperature measurement is commonly used to monitor temperature due to the high temperatures and high cleanliness requirements. This approach has a drawback: during the preparation process, silicon-carbon gaseous compounds or particles easily condense on the temperature-measuring quartz glass surface, resulting in inaccurate temperature measurements and affecting the determination of the silicon carbide growth state. Infrared thermometers, used as temperature monitors for silicon carbide single crystal growth equipment, cannot effectively measure the furnace temperature if the temperature measurement holes become clogged, leading to a mismatch between the actual and measured temperatures. This, in turn, prevents closed-loop temperature control, making the growth process uncontrollable and potentially leading to growth failure. Summary of the Invention

[0003] To address these issues, the present invention discloses a mechanism for cleaning the temperature measurement window during silicon carbide growth and a closed-loop temperature control method. The temperature measurement window is automatically cleaned based on temperature differentials. This mechanism also allows for manual cleaning when contamination is detected, ensuring the reliability of infrared temperature measurement. Based on this data, closed-loop temperature control is achieved in conjunction with the silicon carbide production process.

[0004] To achieve the above-mentioned object, the present invention provides the following technical solution: a temperature closed-loop control method based on a mechanism for cleaning a temperature measuring window during silicon carbide growth, characterized in that it comprises the following steps:

[0005] S1. First, set the three parameters θ, ɑ, and β in the single crystal growth furnace control page. Set the device to a temperature judgment value θ, and set the empirical value κ of the power corresponding to this temperature, and set the empirical value ν of the temperature deviation corresponding to this power. Let ɑ = κ, β = ν, where ɑ is the power value corresponding to θ calculated in the subsequent production process, β is the deviation value calculated in the subsequent production process, and ε is the offset.

[0006] S2. Before the next furnace process begins, sample and count the output power of the induction heating power supply corresponding to the two temperature ranges of θ-30°C and θ+30°C during the normal growth process of the previous furnace under the same process conditions of the equipment, with the same number of samples in the two temperature ranges;

[0007] S3. Add the heating power output values ​​sampled from the two temperature ranges to calculate the mean μ. This means that the mean follows Chebyshev's law of large numbers and gradually approaches the overall mean. Therefore, add the output power mean μ obtained from this sampling to the empirical value ɑ set for the previous furnace, divide the sum by 2, and further calculate the mean. This value is assigned to ɑ to reduce the error.

[0008] S4. Subtract the calculated mean μ from the empirical value ɑ set in the previous furnace, and then take the absolute value Δ. Then, by sampling the ratio of the temperature to the power supply output within the temperature range θ±β during the normal growth process of the previous furnace, take the average of these values ​​and calculate the temperature value corresponding to Δ. This value is then added to the offset ε and assigned to β.

[0009] S5. During the growth process of a new furnace, when the output power reaches ɑ and stabilizes for a period of time, observe whether the infrared temperature measurement value is lower than the updated θ-β value. If it is lower than this value, the temperature measurement hole is determined to be blocked, and the temperature measurement window cleaning mechanism is automatically cleaned by the PLC.

[0010] S6. Similarly, before the production process of the nth furnace, the induction power output power corresponding to the two temperature ranges θ±β of the n-1 furnace is sampled to calculate the mean μ1. At the same time, all the sampled data of the output power of the first n-2 furnaces are combined with the set empirical value κ to calculate the mean μ2. As the amount of sampled data increases, the sample mean gradually approaches the overall mean. At the same time, as the amount of data increases, the influence of manual experience decreases. Then, the mean is further calculated by adding μ1 and μ2 and dividing by 2, and the value is assigned to ɑ. Considering that the equipment status will gradually change with continuous use, but the status of equipment in adjacent furnaces will not differ much, further calculating the mean is equivalent to increasing the proportion of the sampled data of the previous furnace.

[0011] S7. Subtract μ1 from μ2 and take its absolute value Δ. Take the average value μ3 of the ratio of temperature to power supply output power within the θ±β temperature range of furnace n-1 during normal growth. Simultaneously, take the average value μ4 of all sampled data on the ratio of temperature to power supply output power within the θ±β temperature range of furnace n-2. Then, add μ3 and μ4 and divide by 2 to calculate the ratio of temperature to power supply output power. Then, calculate the temperature value corresponding to Δ, add this value to the offset ε, and assign it to β.

[0012] S8. During the growth process of the nth furnace, when the output power reaches ɑ and stabilizes for a period of time, observe whether the infrared temperature measurement value is lower than the updated θ-β value. If it is lower than this value, it is determined that the temperature measuring hole is blocked, an alarm is generated, and the temperature measuring window is automatically cleaned by the PLC-driven cleaning window mechanism; otherwise, there is no blockage, the infrared thermometer will feed back the temperature value to the PLC, and the PLC will analyze the temperature and adjust the output power of the heating power supply to achieve closed-loop control of the temperature.

[0013] Preferably, a temperature closed-loop control method based on a mechanism for cleaning a temperature measuring window during silicon carbide growth is provided, wherein the mechanism for cleaning a temperature measuring window during silicon carbide growth comprises a vacuum chamber, a water-cooled flange seat is installed above the vacuum chamber, a support seat is installed above the vacuum chamber, and the support seat is located above the water-cooled flange seat, a thermometer is installed above the support seat, an inner hole communicating with the vacuum chamber is provided at the lower end of the water-cooled flange seat, an observation window is installed at the upper end of the water-cooled flange seat, and a connecting rod hole communicating with the inner hole is provided on one side of the water-cooled flange seat;

[0014] A cylinder is installed above the vacuum chamber, the piston rod of the cylinder is connected to one end of a connecting rod, the other end of the connecting rod passes through the connecting rod hole and extends into the inner hole, and two scrapers are installed on the other end of the connecting rod, and the scrapers are in direct contact with the lower end surface of the observation window.

[0015] Preferably, the mechanism for cleaning the temperature measuring window during the growth of silicon carbide further includes a metal bellows, one end of which is fixed on the side end face of the water-cooled flange seat, and the other end is connected to the piston rod of the cylinder through a fixed seat, a sealing groove is provided at the lower end of the water-cooled flange seat, and the interior of the water-cooled flange seat has a water-cooling structure.

[0016] Preferably, the mechanism for cleaning the temperature measuring window during the growth of silicon carbide also includes a guide block and two external guide rods. The guide block is fixedly connected to the outer shell of the cylinder. Connection holes are opened on both sides of the guide block. One end of the two external guide rods is respectively connected to the connection holes, and the other end of the two external guide rods is connected to the water-cooled flange seat.

[0017] Preferably, the mechanism for cleaning the temperature measuring window during the growth process of silicon carbide also includes two internal guide rods, one end of the internal guide rod is connected to the outer side of the water-cooled flange seat, and the other end of the internal guide rod is connected to the side wall of the inner hole, and the two ends of the scraper connect the two internal guide rods.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention sets specific parameters on the control panel and samples data for specific temperature sections. When the amount of production data in the early stage of the equipment is limited, manual experience is taken into account, and the empirical values ​​are analyzed together with the data during the actual growth process of the equipment, thereby reducing deviations. In addition, as the number of growth times increases and the data is superimposed, the analysis results will become closer and closer to the actual results of the equipment, and the role of manual experience will be weakened. At the same time, considering that the long-term use of the equipment may cause the equipment condition to change slowly, the proportion of the previous furnace data is increased to make the analysis results more accurate. Finally, in order to avoid the influence of unknown factors on the analysis results and misjudgment, the bias is increased to make the analysis model more reliable.

[0020] The present invention effectively solves the problem that the infrared thermometer cannot effectively measure temperature due to the blockage of the temperature measuring window, resulting in the inability to achieve closed-loop temperature control. When the model monitors abnormal temperature in a specific temperature range, it will be determined that the temperature measuring hole is blocked. The temperature measuring window cleaning mechanism is driven by PLC to clean the temperature measuring window, thereby ensuring the accuracy of the temperature value measured by the infrared thermometer and realizing closed-loop temperature control. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 A schematic diagram of the structure of a mechanism for cleaning the temperature measuring window;

[0023] Figure 2 A top view of the mechanism for cleaning the temperature measuring window. DETAILED DESCRIPTION

[0024] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0025] In order to enable those skilled in the art to better understand the present invention, the following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0026] A temperature closed-loop control method based on a mechanism for cleaning a temperature measuring window during silicon carbide growth comprises the following steps:

[0027] S1. First, set the three parameters θ, ɑ, and β in the single crystal growth furnace control page, set the device to a temperature judgment value θ, and set the experience value κ of the power corresponding to the temperature, and set the experience value of the temperature deviation corresponding to the power. n , let ɑ = k , β = n , ɑ is the corresponding power value of θ calculated in the subsequent production process, β is the deviation value calculated in the subsequent production process, e is the offset;

[0028] S2. Before the next furnace process begins, sample and count the output power of the induction heating power supply corresponding to the two temperature ranges of θ-30°C and θ+30°C during the normal growth process of the previous furnace under the same process conditions of the equipment, with the same number of samples in the two temperature ranges;

[0029] S3. Add the heating power output values ​​sampled from the two temperature ranges to calculate the mean μ. This means that the mean follows Chebyshev's law of large numbers and gradually approaches the overall mean. Therefore, add the output power mean μ obtained from this sampling to the empirical value ɑ set for the previous furnace, divide the sum by 2, and further calculate the mean. This value is assigned to ɑ to reduce the error.

[0030] S4. Subtract the calculated mean μ from the empirical value ɑ set in the previous furnace, and then take the absolute value Δ. Then, by sampling the ratio of the temperature to the power supply output within the temperature range θ±β during the normal growth process of the previous furnace, take the average of these values ​​and calculate the temperature value corresponding to Δ. This value is then added to the offset ε and assigned to β.

[0031] S5. During the growth process of a new furnace, when the output power reaches ɑ and stabilizes for a period of time, observe whether the infrared temperature measurement value is lower than the updated θ-β value. If it is lower than this value, the temperature measurement hole is determined to be blocked, and the temperature measurement window cleaning mechanism is automatically cleaned by the PLC.

[0032] S6. Similarly, before the production process of the nth furnace, the induction power output power corresponding to the two temperature ranges θ±β of the n-1 furnace is sampled to calculate the mean μ1. At the same time, all the sampled data of the output power of the first n-2 furnaces are combined with the set empirical value κ to calculate the mean μ2. As the amount of sampled data increases, the sample mean gradually approaches the overall mean. At the same time, as the amount of data increases, the influence of manual experience decreases. Then, the mean is further calculated by adding μ1 and μ2 and dividing by 2, and the value is assigned to ɑ. Considering that the equipment status will gradually change with continuous use, but the status of equipment in adjacent furnaces will not differ much, further calculating the mean is equivalent to increasing the proportion of the sampled data of the previous furnace.

[0033] S7. Subtract μ1 from μ2 and take its absolute value Δ. Take the average value μ3 of the ratio of temperature to power supply output power within the θ±β temperature range of furnace n-1 during normal growth. Simultaneously, take the average value μ4 of all sampled data on the ratio of temperature to power supply output power within the θ±β temperature range of furnace n-2. Then, add μ3 and μ4 and divide by 2 to calculate the ratio of temperature to power supply output power. Then, calculate the temperature value corresponding to Δ, add this value to the offset ε, and assign it to β.

[0034] S8. During the growth process of the nth furnace, when the output power reaches ɑ and stabilizes for a period of time, observe whether the infrared temperature measurement value is lower than the updated θ-β value. If it is lower than this value, it is determined that the temperature measuring hole is blocked, an alarm is generated, and the temperature measuring window is automatically cleaned by the PLC-driven cleaning window mechanism; otherwise, there is no blockage, the infrared thermometer will feed back the temperature value to the PLC, and the PLC will analyze the temperature and adjust the output power of the heating power supply to achieve closed-loop control of the temperature.

[0035] like Figure 1-2 A temperature closed-loop control method based on a mechanism for cleaning a temperature measuring window during silicon carbide growth is shown. The mechanism for cleaning a temperature measuring window during silicon carbide growth comprises a vacuum chamber 1, a water-cooled flange seat 2 mounted above the vacuum chamber 1, a support seat 3 mounted above the vacuum chamber 1, and the support seat 3 is located above the water-cooled flange seat 2. A thermometer 4 is mounted above the support seat 3. An inner hole communicating with the vacuum chamber 1 is defined at the lower end of the water-cooled flange seat 2, an observation window 5 is mounted at the upper end of the water-cooled flange seat 2, and a connecting rod hole communicating with the inner hole is defined on one side of the water-cooled flange seat 2.

[0036] A cylinder 6 is installed above the vacuum chamber 1, and the piston rod of the cylinder 6 is connected to one end of a connecting rod 7. The other end of the connecting rod 7 passes through the connecting rod hole and extends into the inner hole. Two scrapers 8 are installed on the other end of the connecting rod 7, and the scrapers 8 are in direct contact with the lower end surface of the observation window 5.

[0037] Among them, the mechanism for cleaning the temperature measuring window during the growth process of silicon carbide also includes a metal bellows 12, one end of the metal bellows 12 is fixed on the side end face of the water-cooled flange seat 2, and the other end is connected to the piston rod of the cylinder 6 through a fixed seat. A sealing groove is provided at the lower end of the water-cooled flange seat 2, and the interior of the water-cooled flange seat 2 has a water-cooling structure.

[0038] Among them, the mechanism for cleaning the temperature measuring window during the growth process of silicon carbide also includes a guide block 9 and two external guide rods 10. The guide block 9 is fixedly connected to the outer shell of the cylinder 6. Connection holes are opened on both sides of the guide block 9. One end of the two external guide rods 10 is respectively connected to the connection holes, and the other end of the two external guide rods 10 is connected to the water-cooled flange seat 2.

[0039] Among them, the mechanism for cleaning the temperature measuring window during the growth process of silicon carbide also includes two internal guide rods 11, one end of the internal guide rod 11 is connected to the outer side of the water-cooled flange seat 2, and the other end of the internal guide rod 11 is connected to the side wall of the inner hole, and the two ends of the scraper 8 connect the two internal guide rods 11.

[0040] The above-mentioned thermometer 4 is an infrared thermometer.

[0041] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A temperature closed-loop control method based on a mechanism for cleaning a temperature measuring window during silicon carbide growth, characterized in that: The steps include: S1. First, set the three parameters θ, ɑ, and β in the single crystal growth furnace control page, set the device to a temperature judgment value θ, and set the experience value κ of the power corresponding to the temperature, and set the experience value of the temperature deviation corresponding to the power. ν , let ɑ = κ , β = ν , ɑ is the corresponding power value of θ calculated in the subsequent production process, β is the deviation value calculated in the subsequent production process, ε is the offset; S2. Before the next furnace process begins, sample and count the output power of the induction heating power supply corresponding to the two temperature ranges of θ-30°C and θ+30°C during the normal growth process of the previous furnace under the same process conditions of the equipment, with the same number of samples in the two temperature ranges; S3. Add the heating power output values ​​sampled from the two temperature ranges to calculate the mean μ. This means that the mean follows Chebyshev's law of large numbers and gradually approaches the overall mean. Therefore, add the output power mean μ obtained from this sampling to the empirical value ɑ set for the previous furnace, divide the sum by 2, and further calculate the mean. This value is assigned to ɑ to reduce the error. S4. Subtract the calculated mean μ from the empirical value ɑ set in the previous furnace, and then take the absolute value Δ. Then, by sampling the ratio of the temperature to the power supply output within the temperature range θ±β during the normal growth process of the previous furnace, take the average of these values ​​and calculate the temperature value corresponding to Δ. This value is then added to the offset ε and assigned to β. S5. During the growth process of a new furnace, when the output power reaches ɑ and stabilizes for a period of time, observe whether the infrared temperature measurement value is lower than the updated θ-β value. If it is lower than this value, the temperature measurement hole is determined to be blocked, and the temperature measurement window cleaning mechanism is automatically cleaned by the PLC. S6. Similarly, before the production process of the nth furnace, the induction power output power corresponding to the two temperature ranges θ±β of the n-1 furnace is sampled to calculate the mean μ1. At the same time, all the sampled data of the output power of the first n-2 furnaces are combined with the set empirical value κ to calculate the mean μ2. As the amount of sampled data increases, the sample mean gradually approaches the overall mean. At the same time, as the amount of data increases, the influence of manual experience decreases. Then, the mean is further calculated by adding μ1 and μ2 and dividing by 2, and the value is assigned to ɑ. Considering that the equipment status will gradually change with continuous use, but the status of equipment in adjacent furnaces will not differ much, further calculating the mean is equivalent to increasing the proportion of the sampled data of the previous furnace. S7. Subtract μ1 from μ2 and take its absolute value Δ. Take the average value μ3 of the ratio of temperature to power supply output power within the θ±β temperature range of furnace n-1 during normal growth. Simultaneously, take the average value μ4 of all sampled data on the ratio of temperature to power supply output power within the θ±β temperature range of furnace n-2. Then, add μ3 and μ4 and divide by 2 to calculate the ratio of temperature to power supply output power. Then, calculate the temperature value corresponding to Δ, add this value to the offset ε, and assign it to β. S8. During the growth process of the nth furnace, when the output power reaches ɑ and stabilizes for a period of time, observe whether the infrared temperature measurement value is lower than the updated θ-β value. If it is lower than this value, it is determined that the temperature measuring hole is blocked, an alarm is generated, and the temperature measuring window is automatically cleaned by the PLC-driven cleaning window mechanism; otherwise, there is no blockage, the infrared thermometer will feed back the temperature value to the PLC, and the PLC will analyze the temperature and adjust the output power of the heating power supply to achieve closed-loop control of the temperature.

2. A temperature closed-loop control method based on a mechanism for cleaning a temperature measuring window during silicon carbide growth according to claim 1, wherein: A mechanism for cleaning a temperature measuring window during silicon carbide growth comprises a vacuum chamber, wherein a water-cooled flange seat is installed above the vacuum chamber, and wherein a support seat is installed above the vacuum chamber, and the support seat is located above the water-cooled flange seat, a thermometer is installed above the support seat, an inner hole communicating with the vacuum chamber is formed at the lower end of the water-cooled flange seat, an observation window is installed at the upper end of the water-cooled flange seat, and a connecting rod hole communicating with the inner hole is formed on one side of the water-cooled flange seat; A cylinder is installed above the vacuum chamber, the piston rod of the cylinder is connected to one end of a connecting rod, the other end of the connecting rod passes through the connecting rod hole and extends into the inner hole, and two scrapers are installed on the other end of the connecting rod, and the scrapers are in direct contact with the lower end surface of the observation window.

3. The temperature closed-loop control method based on a mechanism for cleaning a temperature measuring window during silicon carbide growth according to claim 2, characterized in that: in, The mechanism for cleaning the temperature measuring window during the growth of silicon carbide also includes a metal bellows, one end of which is fixed to the side end surface of the water-cooled flange seat, and the other end is connected to the piston rod of the cylinder through a fixed seat; a sealing groove is provided at the lower end of the water-cooled flange seat, and the interior of the water-cooled flange seat has a water-cooling structure.

4. The temperature closed-loop control method based on a mechanism for cleaning a temperature measuring window during silicon carbide growth according to claim 3, characterized in that: in, The mechanism for cleaning the temperature measuring window during the growth of silicon carbide also includes a guide block and two external guide rods. The guide block is fixedly connected to the outer shell of the cylinder. Connection holes are opened on both sides of the guide block. One end of the two external guide rods is respectively connected to the connection holes, and the other end of the two external guide rods is connected to the water-cooling flange seat.

5. The temperature closed-loop control method based on a mechanism for cleaning a temperature measuring window during silicon carbide growth according to claim 4, characterized in that: in, The mechanism for cleaning the temperature measuring window during the growth of silicon carbide also includes two internal guide rods, one end of the internal guide rod is connected to the outer side of the water-cooled flange seat, and the other end of the internal guide rod is connected to the side wall of the inner hole, and the two ends of the scraper connect the two internal guide rods.

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