Method for monitoring heater of resistance-heated crystal growth furnace and resistance-heated crystal growth furnace

Abstract

A method for monitoring a heater of a resistance-heated crystal growth furnace, and a resistance-heated crystal growth furnace. The method comprises: acquiring a resistance-temperature characteristic curve representing a temperature dependence of resistance values of a heater during a current process; identifying, as a current inflection point temperature, a temperature corresponding to a minimum resistance value on the resistance-temperature characteristic curve after the process ends; according to the current inflection point temperature and a pre-acquired initial resistance-temperature characteristic curve representing an initial temperature dependence of resistance values, determining an initial resistance value corresponding to the current inflection point temperature on the initial resistance-temperature characteristic curve, wherein the initial resistance-temperature characteristic curve is obtained according to the resistance values of the heater varying with temperature during initial operation; and determining a remaining service life of the heater according to the initial resistance value and an initial inflection point resistance value.

Description

Method for monitoring the heater of a resistance crystal growth furnace and the resistance crystal growth furnace Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing technology, and more specifically, to a method for monitoring the heater of a resistive crystal growth furnace and the resistive crystal growth furnace itself. Background Technology

[0002] In the physical vapor transport (PVT) process for producing silicon carbide (SiC) single crystals, a graphite heater is used to heat the silicon and carbon powders in the crystal growth furnace to approximately 2300°C. During the process, the SiC single crystals produced deposit between the graphite heater and the graphite electrode, increasing the contact resistance and affecting the conductivity of the graphite heater. Furthermore, after each high-temperature heating, the graphite heater undergoes some volatilization and is etched by silicon, leading to a gradual increase in its resistance.

[0003] Because graphite heaters are sealed within a chamber, their condition cannot be directly observed. Disassembly and inspection of the chamber, along with dimensional measurements and material testing after heater removal, are necessary to determine the heater's condition and remaining lifespan. However, disassembly and removal are time-consuming and labor-intensive. Therefore, a method is needed to determine the remaining lifespan of graphite heaters without requiring chamber opening. Summary of the Invention

[0004] This disclosure aims to at least solve one of the technical problems existing in the prior art, and proposes a monitoring method for the heater of a resistance crystal growth furnace and a resistance crystal growth furnace.

[0005] In a first aspect, embodiments of this disclosure provide a method for monitoring the heater of a resistance crystal growth furnace, comprising:

[0006] Obtain the resistance change curve of the heater as a function of temperature during the current process;

[0007] After the process is completed, the temperature corresponding to the minimum resistance value in the resistance change curve is taken as the current inflection point temperature.

[0008] The initial resistance value corresponding to the current inflection point temperature in the initial resistance change curve is determined based on the current inflection point temperature and the initial resistance change curve obtained in advance as the initial resistance value changes with temperature. The initial resistance change curve is obtained based on the change of the resistance value of the heater with temperature when it is first used.

[0009] The remaining lifespan of the heater is determined based on the initial resistance value and the initial inflection point resistance value, wherein the initial inflection point resistance value is the minimum resistance value in the initial resistance change curve.

[0010] Secondly, embodiments of this disclosure also provide a resistance crystal growth furnace, comprising:

[0011] chamber;

[0012] A crucible, disposed within the chamber, is used to hold the material source for producing monocrystalline silicon;

[0013] A heater, arranged around the crucible, is used to heat the material source inside the crucible;

[0014] The monitoring device includes a processor and a memory, the memory storing a computer program. When the processor executes the computer program, it performs a method for monitoring the heater of a resistance crystal growth furnace provided in this disclosure to determine the remaining lifespan of the heater.

[0015] This application has the following beneficial effects:

[0016] The method for monitoring the heater of a resistance crystal growth furnace provided in this disclosure can, after the process is completed, identify the temperature corresponding to the minimum resistance value in the resistance change curve corresponding to the current process as the current inflection point temperature; based on the current inflection point temperature and the pre-obtained initial resistance change curve showing the change of initial resistance value with temperature, determine the initial resistance value corresponding to the current inflection point temperature in the initial resistance change curve; and determine the remaining lifespan of the heater based on the initial resistance value and the initial inflection point resistance value. Without opening the furnace or disassembling the furnace, the above method can determine the remaining lifespan of the heater, reducing production costs and improving the utilization rate of the crystal growth furnace. Attached Figure Description

[0017] Figure 1 is a schematic diagram of the resistivity crystal growth furnace provided in an embodiment of this disclosure;

[0018] Figure 2 is a flowchart of a method for monitoring the heater of a resistance crystal growth furnace according to an embodiment of this disclosure;

[0019] Figure 3 is a schematic diagram of resistance detection of a heater provided in an embodiment of this disclosure;

[0020] Figure 4 is a fitting curve of the initial resistance value of the heater provided in the embodiment of this disclosure as a function of temperature;

[0021] Figure 5 is a schematic diagram of the change in the resistance value of the heater over time in this embodiment;

[0022] Figure 6 is a schematic diagram of the connection between the copper electrode and the graphite electrode in this embodiment;

[0023] Figure 7 is a graph showing the change in the resistance of the heater over time in this embodiment;

[0024] Figure 8 is a schematic diagram of the connection between the graphite electrode and the heater in this embodiment;

[0025] Figure 9 is a schematic diagram of the copper electrode in this embodiment;

[0026] Figure 10 is a flowchart of the method for monitoring the heater of a resistance crystal growth furnace provided in this embodiment;

[0027] Figure 11 is a block diagram of an apparatus for monitoring the heater of a resistive crystal growth furnace according to an embodiment of the present disclosure. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of this disclosure, the temperature control device and the reaction chamber using it provided in this disclosure will be described in detail below with reference to the accompanying drawings.

[0029] In the growth of SiC single crystals via the PVT method, the SiC crystal is placed at the top of the thermal field within the chamber as a seed crystal; silicon powder and carbon powder are placed at the bottom of the thermal field within the chamber as feedstocks for heating; and argon gas is introduced into the chamber to control the gas pressure. During the SiC crystal growth process, the seed crystal adheres to the upper part of the SiC crystal at a lower temperature, while the feedstocks are at a higher temperature. The feedstocks sublimate and crystallize on the seed crystal at the cold end, thereby obtaining the SiC single crystal.

[0030] Figure 1 is a schematic diagram of the resistive crystal growth furnace provided in the embodiment of the application. As shown in Figure 1, the resistive crystal growth furnace includes a chamber 1 and a top cover 10. Graphite insulation felt 8 is embedded inside the chamber 1 to reduce heat radiation loss.

[0031] The crucible 2 is located at the bottom of the chamber 1, and a support 3 is installed at the bottom of the crucible 2 to support it. A support member 4 is provided between the support 3 and the crucible 2. The support member 4 can make the crucible more stable and reduce heat dissipation from the bottom of the crucible 2.

[0032] A heater 5 (e.g., a graphite heater) is arranged around the crucible 2 to heat the silicon powder and carbon powder materials inside the crucible 2. The heater 5 is electrically connected to a power source (not shown in the figure) through a graphite electrode 6 and a copper electrode 7. The power source provides electrical energy for the production of SiC single crystals.

[0033] During the production of SiC single crystals, prolonged high-temperature environments cause SiC single crystals to deposit between the heater 5 and the graphite electrode 6, increasing the contact resistance between the heater and the graphite electrode. The heater also experiences some volatilization and silicon etching, leading to a gradual increase in resistance and affecting its lifespan. Because the heater is enclosed within a chamber, malfunctions necessitate disassembly, chamber opening, and heater removal for dimensional measurements and material testing to determine the cause of the malfunction and assess its remaining lifespan. However, disassembly and heater removal are time-consuming and labor-intensive, reducing the efficiency of the production equipment.

[0034] In the production of SiC single crystals, the presence of short-circuit faults in the heaters is monitored by detecting the voltage and current output from each power supply circuit, thus determining whether the heaters require maintenance. However, short-circuit detection based on power supply outputs only triggers an alarm when a short circuit occurs in the heater. Therefore, this monitoring method cannot predict risks and can easily lead to production interruptions.

[0035] Therefore, this disclosure provides a method and apparatus for monitoring the heater of a resistive crystal growth furnace, and the crystal growth furnace itself, which can assess the cause of heater malfunctions and evaluate the remaining lifespan without disassembling and inspecting the heater.

[0036] In a first aspect, embodiments of this disclosure provide a method for monitoring the heater of a resistive crystal growth furnace.

[0037] Figure 2 is a flowchart of a method for monitoring the heater of a resistance crystal growth furnace according to an embodiment of this disclosure. As shown in Figure 2, the method for monitoring the heater of a resistance crystal growth furnace according to an embodiment of this disclosure includes:

[0038] Step S201: Obtain the resistance change curve of the heater as the temperature changes during the current process.

[0039] In some embodiments, the heater includes, but is not limited to, a resistance heater, such as a graphite heater.

[0040] In some embodiments, the resistance value of the heater can be obtained by measuring a resistance meter.

[0041] In this embodiment of the disclosure, the power source includes a DC power source or an AC power source, meaning that both DC and AC power sources can provide electrical energy for the production of SiC single crystals.

[0042] Figure 3 is a schematic diagram of the resistance detection of a heater according to an embodiment of this disclosure. As shown in Figure 3, taking a DC power supply as an example, the power supply includes multiple power modules 31. Each power module 31 corresponds to a heater 5, and the power module 31 and the heater 5 are electrically connected through a cable 32 and a graphite electrode 6. Specifically, the power module 31 is electrically connected to the graphite electrode 6 through the cable 32, and the graphite electrode 6 is electrically connected to the heater 5. The power module 31 provides electrical energy to the heater 5 electrically connected to the power module 31. A resistance detector 33 is installed at the output end of the power module 31 and is electrically connected to the cable 32.

[0043] It should be noted that when the power supply is AC, the resistance detector 33 can also be installed on the cable at the output end of the power module 31 to detect the resistance of the corresponding heater. To save space, these will not be listed here individually.

[0044] A resistance meter can measure the resistance of a heater, the resistance of a graphite electrode, the contact resistance between the heater and the graphite electrode, and the contact resistance between a copper electrode and the graphite electrode. Therefore, the resistance value R measured by the resistance meter is... Total The resistance value R of the heater H The resistance value R of the graphite electrode E and the total contact resistance R CTotal The sum of all. Total contact resistance R. CTotal R is the contact resistance value between the heater and the graphite electrode. C1 The contact resistance value R between the copper electrode and the graphite electrode C2 The sum of .

[0045] The calculation formula is: R Total =R H +R E +R CTotal ;

[0046] Among them, R CTotal =R C1 +R C2 .

[0047] In this embodiment, the resistances of the copper electrode, the graphite electrode, the contact resistance between the heater and the graphite electrode, and the contact resistance between the copper electrode and the graphite electrode are known values. During the process, the temperature changes of the copper electrode and the graphite electrode are relatively small, therefore R... E and R CTotal The resistance change is relatively small. Specifically, R E +R CTotal This can be considered a constant, known value. The total resistance R is measured. Total Then, using the total resistance R Total Subtract R E and R CTotalThe resistance value R of the heater can then be obtained. H .

[0048] When calculating the inflection point resistance value, subtract R from the total inflection point resistance value. E and R CTotal The inflection point resistance value of the heater can then be obtained.

[0049] In this embodiment of the disclosure, temperature can be measured using a temperature sensor (such as a thermocouple, laser thermometer, etc.). In some embodiments, the temperature of the molten raw material is used instead of the temperature of the heater.

[0050] During the process, the resistance value of the heater and the corresponding temperature are collected. Then, a resistance change curve of the heater as a function of temperature during the current process can be obtained through fitting.

[0051] In some embodiments, obtaining a resistance change curve of the heater's resistance value as a function of temperature during the current process includes: collecting multiple resistance values ​​of the heater and their corresponding temperatures during the current process; and fitting the multiple resistance values ​​and their corresponding temperatures to obtain a resistance change curve of the heater's resistance value as a function of temperature during the current process.

[0052] In some embodiments, during the current process, the resistance value of the heater is collected by a resistance detector and the temperature of the heater is collected by a temperature sensor. The resistance detector and the temperature sensor collect data synchronously to ensure that the resistance value and temperature of the heater correspond.

[0053] This disclosure does not limit the acquisition frequency of the resistance detector and temperature sensor. The higher the acquisition frequency, the more resistance values ​​and temperature points are collected, and the more accurate the resistance change curve obtained through subsequent fitting.

[0054] In some embodiments, multiple acquisition temperatures can be preset. When the temperature reaches the acquisition temperature, the resistance value of the heater is acquired, thereby obtaining multiple resistance values ​​and the corresponding temperature.

[0055] After collecting multiple resistance values ​​and corresponding temperatures of the heater, a fitting process is performed based on these values ​​to obtain a fitted curve showing the resistance value changing with temperature. This fitted curve can be used as the resistance change curve of the heater as a function of temperature. If the collected resistance values ​​and corresponding temperatures are from the current process, the fitted curve will represent the resistance value changing with temperature during the current process. If the collected resistance values ​​and corresponding temperatures are from the initial process, the fitted curve will represent the initial resistance change curve.

[0056] Figure 4 is a fitting curve showing the change of the initial resistance value of the heater as a function of temperature according to an embodiment of this disclosure. As shown in Figure 4, the initial resistance value of the heater first decreases and then increases with the increase of temperature. The minimum value of the initial resistance value is R0. In this embodiment, the minimum resistance value in the initial process is taken as the initial inflection point resistance value R0, and the temperature corresponding to this initial inflection point resistance value is T0.

[0057] After determining the current inflection point temperature corresponding to the current inflection point resistance value in the current process, the initial resistance value corresponding to the current inflection point temperature in the initial resistance change curve can be determined by the resistance change curve of the initial resistance value as a function of temperature, denoted as R. T2 .

[0058] Step S202: After the process is completed, find the temperature corresponding to the minimum resistance value in the resistance change curve as the current inflection point temperature.

[0059] During the production of SiC single crystals, the resistance of the heater first decreases and then increases with the increase of temperature. Therefore, the inflection point resistance value is the lowest resistance value in the resistance change curve of the heater, and the temperature corresponding to the inflection point resistance value is the inflection point temperature.

[0060] In this embodiment of the application, after the current process is completed, the temperature corresponding to the minimum resistance value in the resistance change curve is taken as the current inflection point temperature.

[0061] Step S203: Determine the initial resistance value corresponding to the current inflection point temperature in the initial resistance change curve based on the current inflection point temperature and the initial resistance change curve obtained in advance as the initial resistance value changes with temperature.

[0062] The initial resistance change curve is obtained based on the change in the resistance value of the heater with temperature when it is first used.

[0063] The initial resistance change curve is the curve showing the change in resistance value with temperature during the initial process of the heater. During the initial process of the heater, multiple resistance values ​​and corresponding temperatures are obtained. The initial resistance change curve is obtained by fitting the curve, and the resistance value corresponding to the current inflection point temperature is selected as the initial resistance value.

[0064] Step S204: Determine the remaining lifespan of the heater based on the initial resistance value and the initial inflection point resistance value.

[0065] In some embodiments, the remaining lifespan of the heater is determined based on the initial resistance value, the initial inflection point resistance value, and the preset limit inflection point resistance value.

[0066] In some embodiments, the remaining lifespan of the heater is calculated by the following steps: calculating the difference between the initial resistance value and the initial inflection point resistance value to obtain a first difference; calculating the difference between the preset limit inflection point resistance value and the initial inflection point resistance value to obtain a second difference; calculating the ratio of the first difference and the second difference to obtain a detection ratio; and determining the remaining lifespan of the heater based on the detection ratio.

[0067] Specifically, the remaining lifespan of the heater is calculated using formula (1). Remaining lifespan = 1 - (R) T -R0) / (R S -R0) (1)

[0068] Among them, R T R0 represents the initial resistance value at the current inflection point temperature corresponding to the current process, as shown in the initial resistance value versus initial resistance change curve. S This indicates the resistance value at the extreme inflection point.

[0069] In some embodiments, the initial inflection point resistance value is obtained through the following steps:

[0070] During the initial process of the heater, resistance values ​​of the heater at different temperatures are collected to obtain multiple relationships between temperature and heater resistance values. Then, these multiple temperature-heater resistance value relationships are fitted to obtain a fitted curve S0. This fitted curve can be used as the initial resistance change curve of the heater as a function of temperature. The minimum resistance value in this initial resistance change curve is taken as the initial inflection point resistance value.

[0071] As the heating element is used over time, its resistance decreases due to evaporation, leading to a reduction in the cross-sectional area of ​​the heater. This not only reduces the heater's support strength but, more importantly, increases its resistance. The heater's power P is related to both voltage and resistance, as shown in the equation P = U. 2 Under the same heating power, the heater requires a higher voltage. If the required voltage exceeds the maximum output voltage of the power supply, the power supply cannot provide the necessary heating power, resulting in heating failure. Therefore, when the heater's resistance exceeds the preset limit inflection point resistance value R... S The heater needs to be replaced at this point, meaning the resistance value R at the extreme inflection point needs to be changed. S It could be the resistance value at the inflection point when the heater last operated normally.

[0072] It should be noted that the resistance value R at the extreme inflection point S The resistance value can also be set according to the quality of the heater; this embodiment does not limit this. For example, the resistance value R at the extreme inflection point. S It can be 1.3 times the initial inflection point resistance value R0, that is, R S =1.3R0.

[0073] In some embodiments, the remaining lifespan of the heater can also be determined based on the current inflection point resistance value and the correspondence between the inflection point resistance value and the remaining lifespan. Specifically, the remaining lifespan of the heater can be determined by finding the correspondence between the inflection point resistance value and the remaining lifespan based on the current inflection point resistance value. The correspondence between the inflection point resistance value and the remaining lifespan of the heater can be obtained through the following steps: after each process, the inflection point resistance value of the heater is obtained; the inflection point resistance value obtained from each process is fitted to obtain a fitted line of the inflection point resistance value; and then the correspondence between the inflection point resistance value and the remaining lifespan of the heater is obtained based on the lifespan of the heater and the fitted line.

[0074] This embodiment determines the heater's lifespan by its resistance value, since the heater's power is related to its minimum resistance value. If the voltage required for the minimum resistance value exceeds the maximum output voltage of the power supply, then all other required voltages will also exceed the maximum output voltage. Therefore, this embodiment characterizes the heater's remaining lifespan by the inflection point resistance value.

[0075] In this embodiment of the disclosure, the remaining lifespan of the heater is determined by the initial resistance value R in the initial resistance change curve based on the current inflection point temperature. T2 The initial inflection point resistance value R0 and the preset limit inflection point resistance value R S Yes, the remaining lifespan of the heater can be determined precisely.

[0076] In some embodiments, the limiting inflection point resistance value R S The resistance value can also be set according to the quality of the heater; this embodiment does not limit this. For example, the resistance value R at the extreme inflection point. S It can be 1.3 times the initial inflection point resistance value R0, that is, R S =1.3R0.

[0077] For example, after the second process, the remaining life of the heater can be calculated as follows:

[0078] During the second process, the resistance and temperature of the heater are collected. A second resistance-temperature curve is obtained by fitting the collected resistance and temperature data. Based on this second curve, the second inflection point resistance value R2 can be determined. The corresponding second inflection point temperature T2 is then determined based on the resistance value R2. Finally, the initial resistance value R corresponding to the second inflection point temperature T2 is determined using the initial resistance change curve of the heater as a function of temperature. T2 The initial inflection point resistance value R0 can be determined based on the initial resistance curve of the heater as a function of temperature. The limiting inflection point resistance value R is then preset. STherefore, after the second process, the remaining life of the heater = 1 - (R) T2 -R0) / (R S -R0).

[0079] For example, after the third process, the remaining life of the heater can be calculated as follows:

[0080] During the third process, the resistance and temperature of the heater are collected. A third resistance-temperature curve is obtained by fitting the collected resistance and temperature data. Based on this third curve, the third inflection point resistance value R3 can be determined. Then, the corresponding third inflection point temperature T3 is determined based on the third inflection point resistance value R3. Finally, the initial resistance value R corresponding to the third inflection point temperature T3 is determined using the initial resistance change curve of the heater as a function of temperature. T3 The initial inflection point resistance value R0 can be determined based on the initial resistance curve of the heater as a function of temperature. The limiting inflection point resistance value R is then preset. S Therefore, after the third process, the remaining life of the heater = 1 - (R) T3 -R0) / (R S -R0).

[0081] The remaining life of the heater after the nth process is calculated in the same way as the remaining life of the heater after the second and second processes. Specifically, the mathematical model for the remaining life of the heater can be expressed as: Remaining life = 1 - (R) Tn -R0) / (R S -R0).

[0082] Among them, R Tn R0 represents the initial resistance value at the nth inflection point temperature, as shown in the initial resistance change curve of the initial resistance value versus temperature after the nth process. S This indicates the resistance value at the extreme inflection point.

[0083] In some embodiments, the process of obtaining the resistance change curve of the heater as the resistance value changes with temperature during the current process further includes: obtaining a current slope value based on the resistance change curve of the heater as the resistance value changes with time during the current process; and using the current slope value to monitor the usage status of the heater.

[0084] As mentioned before, the current curve showing the change of the heater's resistance value over time in the current process is obtained by fitting the heater's resistance value and time in the current process, and will not be described again here.

[0085] The resistance value of the heater changes over time depending on the degree of damage to the heater. Figure 5 is a schematic diagram of the resistance value of the heater changing over time in this embodiment. As shown in Figure 5, the resistance value of the heater after deformation caused by volatilization is the first resistance value changing over time curve X1 (e.g., slope approximately 0.1 to 0.3); when the heater (e.g., a graphite heater) is subjected to reactions such as silicon etching and corrosion, its resistance value changes over time curve X2 (e.g., slope approximately 0.3 to 0.6); when the contact resistance (including the contact resistance between the copper electrode and the graphite electrode and the contact resistance between the graphite electrode and the graphite heater, wherein the copper electrode is cooled by cooling water) increases, the resistance value of the heater changes over time curve X3, where the resistance value shows a sudden increase (e.g., slope greater than 1). Therefore, the operating status of the heater can be monitored based on the slope value of the resistance value changing over time curve.

[0086] In some embodiments, the slope of the curve showing the change in the heater's resistance over time can be expressed by formula P. t =(R t+△t -R t ) / △t. Where, P t R represents the slope at time t. t R represents the resistance value of the heater at time t. t+△t This represents the resistance value of the heater at time t+Δt, where Δt represents the time of increase, i.e., the step time.

[0087] In some embodiments, the operating status of the heater is monitored using the current slope value of the current curve of the resistance value changing over time (the curve of the heater's resistance value changing over time during the current process), including:

[0088] It is determined whether the current slope value is within a first preset slope range; in some embodiments, the first preset slope range may include any value greater than or equal to 0.1 and less than 0.3. When the current slope value is greater than or equal to 0.1 and less than 0.3, it is determined that the heater has undergone evaporative aging.

[0089] If the current slope value is within the first preset slope range, a first monitoring message is issued. The first monitoring message is used to indicate the evaporation aging of the heater.

[0090] If the current slope value is outside the first preset slope range, it is determined whether the current slope value is within the second preset slope range, where the minimum endpoint of the second preset slope range is greater than the maximum endpoint of the first preset slope range. In some embodiments, the second preset slope range may include any value greater than or equal to 0.3 and less than 0.6. When the current slope value is greater than or equal to 0.3 and less than 0.6, it is determined that the heater may be at risk of reaction or corrosion.

[0091] If the current slope value is within the second preset slope range, a second monitoring message is issued. The second monitoring message is used to indicate that an inspection is performed after the process is completed to check whether the heater has been reacted or corroded.

[0092] If the current slope value is outside the second preset slope range, determine whether the current slope value is within the third preset slope range, where the minimum endpoint of the third preset slope range is greater than the maximum endpoint of the second preset slope range. The third preset slope range can include any value greater than 1. If the current slope value is greater than 1, it is determined that the heater may have a contact fault, requiring shutdown for maintenance to prevent localized overheating of the contact area and to avoid the heater failing to provide sufficient heat to affect the process.

[0093] If the current slope value is within the third preset slope range, a third monitoring message is issued. The third monitoring message is used to indicate that the heater has a contact fault and needs to be disassembled for inspection, so as to check whether a contact fault has occurred in a timely manner.

[0094] In this embodiment, the first preset slope range, the second preset slope range, and the third preset slope range may be continuous or discontinuous.

[0095] In some embodiments, after issuing the first monitoring message or the second monitoring message, the method further includes: determining the minimum resistance value R in the resistance change curve of the heater as a function of temperature during the current process. T Is it greater than the resistance value R at the limit inflection point? S In the current process, the minimum resistance value R is found in the resistance change curve of the heater as a function of temperature. T If the resistance value exceeds the limit inflection point, a fourth monitoring message is issued, which is used to indicate the need to replace the heater.

[0096] In some embodiments, the limiting inflection point resistance value R S The resistance value R can be set according to the quality of the heater, but this embodiment does not limit it. For example, the resistance value R at the extreme inflection point. S It can be 1.3 times the initial inflection point resistance value R0, that is, R S =1.3R0.

[0097] In this embodiment, the minimum resistance value in the resistance change curve of the heater as a function of temperature during the current process can also be referred to as the current inflection point resistance value R. T At the current inflection point resistance value R T If the resistance value exceeds the limit inflection point, it indicates that the material of the heater has undergone a qualitative change, and a message is sent to replace the heater.

[0098] Figure 6 is a schematic diagram of the connection between the copper electrode and the graphite electrode in this embodiment. As shown in Figure 6, the graphite electrode 6 and the copper electrode 7 are connected by threads. Specifically, the graphite electrode 6 is provided with a threaded hole 61, and the copper electrode 7 is provided with a stud 71. The stud 71 and the threaded hole 61 are matched in size, and the stud 71 is screwed into the threaded hole 61, thereby connecting the graphite electrode 6 and the copper electrode 7. Due to the different coefficients of thermal expansion of the copper electrode 7 and the graphite electrode 6, after multiple high-temperature processes, the contact surface between the copper electrode 7 and the graphite electrode 6 and the fit between the threads deteriorate, resulting in an increase in the contact resistance between the copper electrode 7 and the graphite electrode 6.

[0099] Figure 7 is a graph showing the change in the heater's resistance over time in this embodiment. As shown in Figure 7, the heater's resistance gradually increases with time. Curve Z1 (slope approximately 0.1–0.3) corresponds to signs of deterioration in the contact surface of the contact thermal resistance; curve Z2 (slope approximately 0.3–0.6) corresponds to a deepening deterioration of the contact surface of the contact thermal resistance; and curve Z3 (slope greater than 1) corresponds to a deterioration of the contact surface of the contact thermal resistance that causes the heater to malfunction. It should be noted that the heater's resistance is measured in the same way as the total resistance value. The total resistance value can be obtained by measuring the total resistance value with a resistance meter, and then subtracting the electrode resistance value and the contact resistance value from the total resistance value to obtain the heater's resistance value.

[0100] Figure 8 is a schematic diagram of the connection between the graphite electrode and the heater in this embodiment. As shown in Figure 8, the graphite electrode 6 and the heater 5 are connected by screws 9. That is, multiple screw holes are provided on the heater 5 and the graphite electrode 6, and screws 9 are screwed into the screw holes on the heater 5 and the graphite electrode 6. Each screw hole corresponds to one screw 9, and each graphite electrode 6 can be connected to the heater 5 by multiple screws 9. The number of screws 9 is not limited in this embodiment.

[0101] Because the strength of the copper electrode 7 is easily affected by temperature, a cooling structure is provided inside the copper electrode 7 to ensure that it has a certain strength at high temperatures. Figure 9 is a schematic diagram of the copper electrode structure in this embodiment. As shown in Figure 9, the cooling structure includes a medium channel 72, an inlet 73, and an outlet 74. The medium channel 72 is located inside the copper electrode 7 and is connected to the inlet 73 and the outlet 74. Cooling water enters the medium channel 72 from the inlet 73 and flows out from the outlet 74, thereby carrying away the heat inside the copper electrode 7. A flow meter and a thermometer are installed at the outlet 74 to detect the flow rate and temperature of the cooling water. When the contact thermal resistance between the copper electrode 7 and the graphite electrode 6, and between the graphite electrode 6 and the heater 5, tends to deteriorate, the heat conduction between the copper electrode 7, the graphite electrode 6, and the heater 5 will weaken, the heat transferred to the cooling water will decrease, and the cooling water temperature will drop.

[0102] In some embodiments, the flow meter collects the flow rate and temperature of the cooling water inside the copper electrode in real time. When the cooling water flow rate is normal, but the temperature drops below the preset temperature threshold, it indicates that there may be a risk of contact deterioration in the heater. It is recommended to suspend the process for troubleshooting and issue a warning alarm.

[0103] In some embodiments, monitoring the operating status of the heater using the current slope value further includes: acquiring the flow rate and temperature of cooling water, wherein the cooling water is used to cool the electrodes electrically connected to the heater; and monitoring the operating status of the heater using the flow rate and temperature of the cooling water.

[0104] In some embodiments, the flow rate and temperature of the cooling water can be obtained by a flow meter and a thermometer, and the operating status of the heater can be monitored based on the current slope of the current curve of resistance changing with temperature, the flow rate and temperature of the cooling water.

[0105] In some embodiments, monitoring the operating status of the heater using the flow rate and temperature of cooling water includes:

[0106] The system determines whether the cooling water flow rate is normal and whether the cooling water temperature has dropped below a preset temperature threshold. This embodiment does not limit the specific value of the temperature threshold; for example, the temperature threshold could be 3°C or other values.

[0107] If the cooling water flow rate is normal and the cooling water temperature drops below the temperature threshold, a cooling water monitoring message is issued to indicate that a check should be performed after the process is completed. Then, it is determined whether the current slope value is within the third preset slope range, where the third preset slope can be any value greater than 1.

[0108] When the current slope value is greater than 1, it is considered that the heater may have a contact fault, requiring shutdown for maintenance to prevent localized overheating of the contact area and insufficient heat from affecting the process. Therefore, an alarm message indicating a heater contact fault requiring disassembly and maintenance is issued. If the current slope value is outside the third preset slope range, monitoring ends.

[0109] To better understand this application, the method for monitoring the heater of a resistance crystal growth furnace provided in this embodiment will be described below with reference to Figure 10.

[0110] Figure 10 is a flowchart of a method for monitoring the heater of a resistance crystal growth furnace provided in this embodiment. As shown in Figure 10, the method for monitoring the heater of a resistance crystal growth furnace includes:

[0111] Step S10: Calculate the current slope of the current curve showing the change of resistance value over time.

[0112] Step S11: Determine whether the current slope value is between 0.1 and 0.3 (the first preset slope range). If yes, proceed to step S12; otherwise, proceed to step S15.

[0113] Step S12: Send a message about heater evaporation aging (first monitoring message).

[0114] Step S13: Determine whether the current inflection point resistance value is greater than 1.3R0 (limit inflection point resistance value). If so, proceed to step S14.

[0115] Step S14: Send a message to replace the heater (fourth monitoring message).

[0116] Step S15: Determine whether the current slope value is between 0.3 and 0.6 (the second preset slope range). If yes, proceed to step S16; otherwise, proceed to step S19.

[0117] Step S16: Issue a reminder message (second monitoring message) for post-process inspection to check whether the heater has been reacted or corroded.

[0118] Step S17, determine the current inflection point resistance value R. T Is it greater than 1.3R0 (the resistance value at the limit inflection point)? If so, proceed to step S18.

[0119] Step S18: Send a message that the heater needs to be replaced (fourth monitoring message).

[0120] Step S19: Determine whether the current slope value is greater than 1 (the third preset slope range). If yes, proceed to step S110; otherwise, end the process.

[0121] In step S110, an alarm message (third monitoring message) is sent indicating that the heater has a contact fault and needs to be disassembled for inspection, in order to check whether a contact fault has occurred.

[0122] Step S20: Collect the flow rate and temperature of the cooling water, and determine whether the flow rate of the cooling water is normal and whether the temperature is below 3°C. If so, proceed to step S21.

[0123] Step S21 indicates a risk of heater contact deterioration; it is recommended to investigate after the process is completed.

[0124] After step S21, step S19 is executed.

[0125] It should be noted that steps S10 and S20 can be executed simultaneously, or step S10 can be executed first and then step S20; or step S20 can be executed first and then step S10.

[0126] The method disclosed herein for monitoring the heater of a resistance crystal growth furnace involves identifying the temperature corresponding to the minimum resistance value in the resistance change curve of the current process after the process is completed, using this temperature as the current inflection point temperature. Based on the current inflection point temperature and the initial resistance change curve obtained beforehand showing the change of the initial resistance value with temperature, the method determines the initial resistance value corresponding to the current inflection point temperature in the initial resistance change curve. Then, based on the initial resistance value and the initial inflection point resistance value, the remaining lifespan of the heater is determined. This method can determine the remaining lifespan of the heater without opening the chamber or disassembling the machine, thereby reducing production costs and improving the utilization rate of the crystal growth furnace.

[0127] Secondly, embodiments of this disclosure provide an apparatus for monitoring the heater of a resistive crystal growth furnace.

[0128] Figure 11 is a block diagram of an apparatus for monitoring the heater of a resistance crystal growth furnace according to an embodiment of this disclosure. As shown in Figure 11, the apparatus for monitoring the heater of a resistance crystal growth furnace provided in this embodiment includes:

[0129] The acquisition module 111 is used to acquire the resistance change curve of the heater as the temperature changes during the current process.

[0130] The first determining module 112 is used to find the temperature corresponding to the minimum resistance value in the resistance change curve after the process is completed as the current inflection point temperature; and to determine the initial resistance value corresponding to the current inflection point temperature in the initial resistance change curve based on the current inflection point temperature and the initial resistance change curve of the initial resistance value obtained in advance as the initial resistance value changes with temperature. The initial resistance change curve is obtained based on the change of the resistance value of the heater with temperature when it is first used.

[0131] The second determining module 113 is used to determine the remaining life of the heater based on the initial resistance value and the initial inflection point resistance value, wherein the initial inflection point resistance value is the minimum resistance value in the initial resistance change curve.

[0132] The apparatus for monitoring the heater of a resistance crystal growth furnace provided in this disclosure can perform all the steps mentioned in the method for monitoring the heater of a resistance crystal growth furnace provided in this disclosure, and will not be repeated here for the sake of brevity.

[0133] The device disclosed herein for monitoring the heater of a resistance crystal growth furnace includes an acquisition module that acquires a resistance change curve of the heater as the resistance value changes with temperature during the current process. A first determination module identifies the temperature corresponding to the minimum resistance value in the resistance change curve corresponding to the current process as the current inflection point temperature after the process ends. Based on the current inflection point temperature and the pre-acquired initial resistance change curve as the initial resistance value, the initial resistance value corresponding to the current inflection point temperature in the initial resistance change curve is determined. A second determination module determines the remaining lifespan of the heater based on the initial resistance value and the initial inflection point resistance value. The remaining lifespan of the heater can be determined without opening the cavity or disassembling the machine, reducing production costs and improving the utilization rate of the crystal growth furnace.

[0134] Thirdly, embodiments of this disclosure also provide a resistance crystal growth furnace.

[0135] As shown in Figure 1, the resistance crystal growth furnace provided in this embodiment includes: a chamber 1, a crucible 2, a heater 5, and a monitoring device (not shown in the figure). The crucible 2 is disposed within the chamber 1 and is used to hold the material source for producing single crystal silicon. The heater 5 is arranged around the crucible 2 and is used to heat the material source within the crucible 2. The monitoring device includes a processor and a memory. The memory stores a computer program. When the processor executes the computer program, it executes the method provided in this embodiment for monitoring the heater of the resistance crystal growth furnace to determine the remaining lifespan of the heater.

[0136] The resistance crystal growth furnace provided in this embodiment uses a detection device to monitor the heater of the resistance crystal growth furnace. The remaining lifespan of the heater is determined based on the initial resistance value corresponding to the current inflection point temperature in the initial resistance change curve and the initial inflection point resistance value. The remaining lifespan of the heater can be determined without opening the cavity or disassembling the machine, which reduces production costs and improves the utilization rate of the resistance crystal growth furnace.

[0137] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A method for monitoring a heater of a resistive crystal growing furnace, wherein, include: Obtain the resistance change curve of the heater as a function of temperature during the current process; After the process is completed, the temperature corresponding to the minimum resistance value in the resistance change curve is identified as the current inflection point temperature. The initial resistance value corresponding to the current inflection point temperature in the initial resistance change curve is determined based on the current inflection point temperature and the initial resistance change curve obtained in advance as the initial resistance value changes with temperature. The initial resistance change curve is obtained based on the change of the resistance value of the heater with temperature when it is first used. The remaining lifespan of the heater is determined based on the initial resistance value and the initial inflection point resistance value, wherein the initial inflection point resistance value is the minimum resistance value in the initial resistance change curve.

2. The method of claim 1, wherein, Determining the remaining lifespan of the heater based on the initial resistance value and the initial inflection point resistance value includes: The remaining lifespan of the heater is determined based on the initial resistance value, the initial inflection point resistance value, and the preset limit inflection point resistance value.

3. The method of claim 1, wherein, The process of obtaining the resistance change curve of the heater as a function of temperature during the current process also includes: Based on the resistance change curve of the heater over time during the current process, the current slope value is obtained; The current slope value is used to monitor the operating status of the heater.

4. The method of claim 3, wherein, The monitoring of the heater's operating status using the current slope value includes: Determine whether the current slope value is within the first preset slope range; If the current slope value is within a first preset slope range, a first monitoring message is issued, wherein the first monitoring message is used to indicate the evaporation aging of the heater.

5. The method according to claim 4, wherein, The method of monitoring the operating status of the heater using the current slope value also includes: If the current slope value is outside the first preset slope range, determine whether the current slope value is within the second preset slope range; If the current slope value is within the second preset slope range, a second monitoring message is issued, wherein the second monitoring message is used to indicate that an inspection is performed after the process is completed; Wherein, the minimum endpoint value of the second preset slope range is greater than the maximum endpoint value of the first preset slope range.

6. The method according to claim 5, wherein, The method of monitoring the operating status of the heater using the current slope value also includes: If the current slope value is outside the second preset slope range, determine whether the current slope value is within the third preset slope range; If the current slope value is within the third preset slope range, a third monitoring message is issued, which is used to indicate that the heater has a contact fault and needs to be disassembled for repair. Wherein, the minimum endpoint value of the third preset slope range is greater than the maximum endpoint value of the second preset slope range.

7. The method according to claim 4, wherein, After sending the first monitoring message, the method further includes: Determine whether the minimum resistance value in the resistance change curve of the heater as the resistance value changes with temperature during the current process is greater than the preset limit inflection point resistance value. If the minimum resistance value in the resistance change curve of the heater as a function of temperature during the current process is greater than the limit inflection point resistance value, a fourth monitoring message is issued, wherein the fourth monitoring message is used to indicate the replacement of the heater.

8. The method according to any one of claims 5 to 7, wherein, After sending the second monitoring message, the method further includes: Determine whether the minimum resistance value in the resistance change curve of the heater as the resistance value changes with temperature during the current process is greater than the preset limit inflection point resistance value. If the minimum resistance value in the resistance change curve of the heater as a function of temperature during the current process is greater than the limit inflection point resistance value, a fourth monitoring message is issued, wherein the fourth monitoring message is used to indicate the replacement of the heater.

9. The method according to any one of claims 3 to 7, wherein, Before monitoring the operating status of the heater using the current slope value, the method further includes: The flow rate and temperature of cooling water are collected, wherein the cooling water is used to cool the electrodes electrically connected to the heater; The operating status of the heater is monitored using the flow rate and temperature of the cooling water.

10. The method according to claim 9, wherein, The monitoring of the heater's operating status using the flow rate and temperature of the cooling water includes: Determine whether the flow rate of the cooling water is normal and whether the temperature of the cooling water has dropped below a preset temperature threshold; When the flow rate of the cooling water is normal and the temperature of the cooling water drops below the temperature threshold, a cooling water monitoring message is issued, wherein the cooling water monitoring message is used to indicate that an inspection is performed after the process is completed.

11. The method according to any one of claims 1 to 7, wherein, The acquisition of the resistance change curve of the heater as a function of temperature during the current process includes: Collect multiple resistance values ​​and corresponding temperatures of the heater during the current process; By fitting the multiple resistance values ​​and their corresponding temperatures, a resistance change curve is obtained showing how the resistance value of the heater changes with temperature during the current process.

12. The method according to claim 1, wherein, Determining the remaining lifespan of the heater based on the initial resistance value and the initial inflection point resistance value includes: Calculate the difference between the initial resistance value and the initial inflection point resistance value to obtain a first difference; Calculate the difference between the preset limit inflection point resistance value and the initial inflection point resistance value to obtain the second difference; Calculate the ratio of the first difference to the second difference to obtain the detection ratio; The remaining lifespan of the heater is determined based on the detection ratio.

13. A resistance crystal growth furnace, wherein, include: chamber; A crucible, disposed within the chamber, is used to hold the material source for producing monocrystalline silicon; A heater, arranged around the crucible, is used to heat the material source inside the crucible; A monitoring device includes a processor and a memory, the memory storing a computer program, wherein when the processor executes the computer program, it performs the method of any one of claims 1 to 12 for monitoring the heater of a resistance crystal growth furnace to determine the remaining life of the heater.

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