A temperature control system and control method for semiconductor furnace tube equipment

Abstract

This invention discloses a temperature control system and method for semiconductor furnace tube equipment. The control system includes a three-phase electric furnace transformer, a power regulator, a heating furnace body, a temperature controller, a programmable logic controller (PLC), and a host computer connected in sequence. The three-phase electric furnace transformer continuously outputs secondary-side voltage and current to the power regulator. The power regulator adjusts the output current from the secondary side of the three-phase electric furnace transformer by receiving the heating power output signal from the temperature controller. The heating furnace body heats the process products loaded inside. The temperature controller calculates the heating output power value of each temperature zone based on the temperature values ​​detected by internal and external thermocouples and then sends the heating output power value to the power regulator. The host computer sends the target temperature parameters from the process menu to the PLC. This invention has advantages such as high temperature control accuracy and good stability.

Description

Technical Field

[0001] This invention relates to the field of semiconductor furnace tube technology, specifically to a temperature control system and control method for semiconductor furnace tube equipment. Background Technology

[0002] Temperature is one of the most important equipment and process parameters in semiconductor furnace tube equipment. Its stability, uniformity, and repeatability are key factors in ensuring the quality and speed of product growth. The temperature control system of semiconductor furnace tube equipment includes the heating furnace body, temperature controller, over-temperature protector, and hardware heating protection interlock circuits. Temperature controllers can be categorized into single-loop control, cascade control, and hybrid control modes. Furnace tube equipment is often used for chemical deposition reactions between various specialty gases and process products. The product reaction process often requires the furnace tube equipment to rapidly reach the target process temperature from the initial process temperature and quickly stabilize at that temperature. A slow furnace body temperature control rate leads to a slow chemical reaction rate between the process product and the specialty gas, resulting in incomplete decomposition of reactant chemical components. This further leads to problems such as excessive particle size, poor uniformity, and unqualified electrical performance indicators, directly affecting the product's processing effect and yield. Therefore, the temperature control system needs to achieve high-precision and rapid temperature control inside the furnace tube to obtain the ideal temperature field for the semiconductor furnace tube equipment.

[0003] Specifically, the rapid heating of the furnace tube equipment from the initial process temperature to the target process temperature requires precise control to ensure complete chemical reaction between the process product and the special gas, while also meeting the requirements for product particle size, electrical properties, and uniformity. Temperature control methods for semiconductor furnace tube equipment generally employ single-loop control, cascade control, and hybrid control modes. Single-loop control is used when thermocouples fail; it offers a faster heating rate, but takes a long time to stabilize at the target process temperature. Hybrid control can be used throughout the entire temperature control process, but is mostly used for furnace tube temperature recovery after lifting the boat; it also suffers from the long time required to stabilize at the target process temperature. Cascade control is generally suitable for process heating; it exhibits smaller temperature fluctuations and higher control accuracy, but the time required to reach the target process temperature is long, making rapid temperature control difficult. Summary of the Invention

[0004] To address the technical problems existing in the prior art, the present invention provides a temperature control system and control method for semiconductor furnace tube equipment with high temperature control accuracy and good stability.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0006] A temperature control system for semiconductor furnace tube equipment includes a three-phase electric furnace transformer, a power regulator, a heating furnace body, a temperature controller, a programmable controller, and a host computer; the three-phase electric furnace transformer, the power regulator, the heating furnace body, the temperature controller, the programmable controller, and the host computer are connected in sequence; the temperature controller is also connected to the power regulator.

[0007] The three-phase electric furnace transformer is used to transform the primary side voltage and current through electromagnetic induction and continuously output the secondary side voltage and current to the power regulator.

[0008] The power regulator is used to adjust the output current from the secondary side of the three-phase electric furnace transformer by receiving the heating power output signal from the temperature controller.

[0009] The heating furnace body is used to heat the process products loaded inside and to feed back the internal and external thermocouple signals to the temperature controller.

[0010] The temperature controller is used to receive the internal and external thermocouple signals fed back by the heating furnace body, calculate the heating output power value of each temperature zone based on the temperature values ​​detected by the internal and external thermocouples, and then send the heating output power value to the power regulator.

[0011] The host computer is used to send the target temperature parameters of the process menu to the programmable controller and to receive the feedback values ​​from the programmable controller.

[0012] As a further improvement to the above technical solution:

[0013] It also includes a protection unit located between the three-phase electric furnace transformer and the three-phase power supply; the protection unit includes a molded case circuit breaker, an AC contactor, and a fuse; the molded case circuit breaker, the AC contactor, and the fuse are connected in sequence.

[0014] It also includes an over-temperature alarm instrument, which is connected to the heating furnace body and the programmable controller respectively, and is used to cut off the furnace heating circuit when the temperature exceeds the instrument's set temperature in each temperature zone.

[0015] The heating furnace body includes a heating unit and various thermocouple acquisition units. The heating unit is used to heat the process products loaded inside according to the process menu on the host computer, and to feed back the internal and external thermocouple output signals and over-temperature thermocouple signals to the temperature controller and over-temperature alarm instrument through the various thermocouple acquisition units.

[0016] The thermocouple acquisition unit includes external furnace thermocouples and internal furnace thermocouples.

[0017] The present invention also discloses a control method based on the temperature control system for semiconductor furnace tube equipment as described above, comprising the following steps:

[0018] Obtain the target process temperature, initial process temperature, and actual process temperature;

[0019] The temperature proportionality coefficient is obtained based on the target process temperature, the initial process temperature, and the actual process temperature.

[0020] The temperature proportionality coefficient is compared with a preset value. If the temperature proportionality coefficient is greater than the preset value, a hybrid temperature control mode is used for temperature control; otherwise, a cascade temperature control mode is used for temperature control.

[0021] As a further improvement to the above technical solution:

[0022] The formula for obtaining the temperature proportionality coefficient k0 based on the target process temperature T0, the initial process temperature, and the actual process temperature is as follows:

[0023] k0 = (actual process temperature - initial process temperature) / (T0 - initial process temperature).

[0024] In the mixed temperature control mode, the proportional coefficient R of the mixed temperature control mode is adjusted in real time according to the temperature proportional coefficient k0; where the proportional coefficient R is proportional to the heating power.

[0025] The specific process of adjusting the proportional coefficient R in real time based on the temperature proportional coefficient k0 is as follows:

[0026] The proportionality coefficient R and the temperature proportionality coefficient k0 satisfy the following linear relationship: R = R0 - 1.25 * k0;

[0027] The value of R0 is 1; the value of k0 is in the range of [0, 0.8].

[0028] Compared with the prior art, the advantages of the present invention are as follows:

[0029] The temperature control system of this invention is applicable to various semiconductor furnace tube equipment. By switching between the proportional control mode and the cascade control mode, it enables the process product to rapidly heat up inside the furnace tube and quickly stabilize at the process target temperature. It can meet the temperature field requirements for rapid reactions between process products and different types of specialty chemical materials; it has high temperature control accuracy, small fluctuations in the process target temperature, and good stability. Attached Figure Description

[0030] Figure 1 This is a topology diagram of the temperature control system of the present invention in an embodiment.

[0031] Figure 2 This is a circuit diagram of the temperature control system of the present invention in an embodiment.

[0032] Figure 3 The diagram shows the temperature control modes of the present invention; where (a) is a hybrid temperature control mode and (b) is a cascade temperature control mode.

[0033] Figure 4 This is a schematic diagram of the temperature control signal of the present invention.

[0034] Figure 5 This is a PLC program design diagram for the temperature control system of the present invention.

[0035] Figure 6 This is a flowchart of an embodiment of the temperature control method of the present invention.

[0036] Legend: 1. Molded case circuit breaker; 2. AC contactor; 3. Fuse; 4. Three-phase electric furnace transformer; 5. Power regulator; 6. Heating furnace body; 601. Heating unit; 602. Thermocouple acquisition unit; 7. Temperature controller; 8. Programmable controller; 9. Host computer; 10. Over-temperature alarm instrument. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 1 As shown, the temperature control system for semiconductor furnace tube equipment provided in this embodiment of the invention includes a molded case circuit breaker 1, an AC contactor 2, a fuse 3, a three-phase electric furnace transformer 4, a power regulator 5, a heating furnace body 6, a temperature controller 7, a programmable controller 8, a host computer 9, and an over-temperature alarm instrument 10.

[0039] Among them, the molded case circuit breaker 1, AC contactor 2, fuse 3, three-phase electric furnace transformer 4, power regulator 5, heating furnace body 6, temperature controller 7, programmable controller 8, and host computer 9 are connected in sequence; the temperature controller 7 is also connected to the power regulator 5; the over-temperature alarm instrument 10 is connected to the heating furnace body 6 and the programmable controller 8 respectively.

[0040] Molded case circuit breaker 1, AC contactor 2 and fuse 3 are used for the protection and control of the three-phase input current of the temperature control system; when the three-phase electric furnace transformer 4 and the heating furnace body 6 are overloaded, they can disconnect the three-phase input current in time to protect the key heating core components such as the three-phase electric furnace transformer 4 and the heating furnace body 6.

[0041] The three-phase electric furnace transformer 4 is the heating power supply for the heating furnace body 6. It transforms the primary side voltage and current through electromagnetic induction and continuously outputs the secondary side voltage and current to the power regulator 5.

[0042] The power regulator 5 is the input current control unit of the temperature control system. By receiving the 4-20mA heating power output signal from the temperature controller 7, it precisely adjusts the output current from the secondary side of the three-phase electric furnace transformer 4.

[0043] The heating furnace body 6 includes a heating unit 601 and each thermocouple acquisition unit 602. The heating furnace body heats the process products loaded inside according to the process menu on the host computer human-machine interface 9, and feeds back the internal and external thermocouple output signals and over-temperature thermocouple signals to the temperature controller 7 and over-temperature alarm instrument 10 through each thermocouple acquisition unit 602.

[0044] The temperature controller 7 receives the input signals from the internal and external thermocouples fed back by the heating furnace body 6, and quickly and accurately calculates the heating output power value of each temperature zone based on the temperature values ​​detected by the internal and external thermocouples. It then sends the heating power value to the power regulator 5 through a 4-20mA electrical signal and exchanges temperature control system data with the programmable controller 8 through the TCP / IP communication protocol.

[0045] The programmable logic controller (PLC) 8 and the host computer 9 are the core components of the temperature control system. The PLC 8, host computer 9 and temperature controller 7 exchange data through the TCP / IP communication protocol. The host computer 9 sends process menu parameters such as target temperature to the PLC 8, which then transmits them to the temperature controller 7. At the same time, the temperature controller 7 feeds back temperature values ​​to the PLC 8, which then transmits the feedback values ​​to the host computer human-machine interface 9.

[0046] The over-temperature alarm instrument 10 is used to detect over-temperature conditions in each temperature zone. If the temperature exceeds the instrument's set temperature, the furnace heating circuit will be immediately cut off.

[0047] Specifically, Figure 2 The three-phase incoming currents L1, L2, and L3 sequentially pass through the molded case circuit breaker 1, AC contactor 2, and fuse 3 to the A, B, and C terminals on the primary side of the three-phase electric furnace transformer 4. Internally, the transformer 4 undergoes electromagnetic induction conversion, and the induced currents output from its internal S1, S2, S3, S4, and S5 terminals sequentially flow to the V1, V2, V3, V4, and V5 terminals of the power regulator 5. The thyristor-controlled unit inside the power regulator 5 outputs current to the corresponding heating wire sections E1, E2, E3, E4, and E5 in each temperature zone of the heating furnace body 6. The thermocouple output signal 7 is connected to the temperature controller 7 and the over-temperature alarm instrument 10.

[0048] like Figure 3 As shown, where Figure 3 (a) is the temperature control block diagram of the hybrid temperature control mode. Figure 3 (b) is a block diagram of temperature control in cascade temperature control mode.

[0049] Figure 3 As shown in (a), the mixed temperature control mode is a single-loop temperature control mode. The host computer 9 sets the process target temperature value and transmits it to the temperature controller 7. The temperature controller 7's internal temperature control program performs PID calculations and outputs the heating power value of each temperature zone to the power regulator 5. The power regulator 5 precisely controls the transformer 4 to output the current to the heating furnace body 6.

[0050] in Figure 3 In (a), the coefficient R is the proportional coefficient of the internal thermocouple detection value in the mixed temperature control mode, and the value of R is in the range of (0,1). The internal thermocouple detection temperature value is k1, and the external thermocouple temperature detection value is k2. The product of k2 and (1-R) ​​and the product of k1 and R are added to obtain a new mixed value. This mixed value is compared with the process target temperature value (set temperature). The larger the difference between the two, the larger the heating output power value obtained by the PID calculation of the internal temperature control program of the temperature controller, and the faster the furnace body heating rate. Conversely, the smaller the difference between the two, the smaller the heating output power value of the temperature controller, and the slower the furnace body heating rate.

[0051] The aforementioned new mixing value is used to adjust the PID and other parameters inside the temperature controller in the form of negative feedback of the temperature control system, so that the furnace temperature is stabilized near the process target temperature.

[0052] Figure 3 In (b), when the cascade command is ON, the temperature is in cascade temperature control mode. The set temperature is used as the internal temperature setpoint, and the output of the internal temperature PID control is used as the external temperature setpoint after cascade calculation. The internal and external temperature closed loops use the same control cycle to improve the system's response speed. Cascade control mode is widely used in situations with large disturbance amplitudes, nonlinearity, large capacity lag, and interrelated parameters due to its strong anti-interference and adaptive capabilities.

[0053] Figure 4 It includes external thermocouple input signal X1, internal thermocouple input signal X2, over-temperature thermocouple signal X3, hybrid temperature control mode proportional coefficient X4, temperature controller hybrid temperature control mode X5, temperature controller cascade temperature control mode X6, temperature controller temperature control super loop X7, furnace body temperature zone heating power output signal X8;

[0054] The external thermocouple input signal X1, internal thermocouple input signal X2, and over-temperature thermocouple signal X3 are thermocouple signals collected from the heating furnace body and transmitted to the temperature controller and over-temperature alarm instrument.

[0055] The host computer 9 writes the proportional coefficient of the process menu into the proportional coefficient X4 of the mixed temperature control mode. The proportional coefficient X4 of the mixed temperature control mode is written into the mixed temperature control mode X5 of the temperature controller through the temperature control program. The mixed temperature control mode X5 of the temperature controller 7 outputs the mixed value detected by the internal and external thermocouples to the slave loop program of the temperature control super loop X7.

[0056] The internal thermocouple input signal X2 feeds back the internal temperature values ​​of each temperature zone to the cascade temperature control mode X6 of the temperature controller. The cascade temperature control mode X6 outputs the temperature detection values ​​to the main circuit program of the temperature controller's super loop X7 via the temperature control program. The temperature control program module of the temperature controller's super loop X7 receives the values ​​from the temperature controller's hybrid temperature control mode X5 and cascade temperature control mode X6, and calculates and outputs the furnace body temperature zone heating power output signal X8 through internal hybrid temperature control mode or cascade temperature control mode.

[0057] The furnace body temperature zone heating power output signal X8 is transmitted to the power regulator 5 to further control the furnace body heating current.

[0058] like Figure 5 As shown, PLC programming includes four parts: communication protocol initialization, forming a communication request, preparing data to initiate communication, and processing after communication.

[0059] First, the PLC's internal register address, number of registers, and data length are accessed using the communication protocol initialization method; at the same time, the corresponding communication request is set through the host computer's human-machine interface.

[0060] When communication is idle, the highest priority communication request is selected in sequence, the host computer human-machine interface prepares the corresponding communication data for the process menu, and initiates communication with the temperature controller.

[0061] Finally, when communication terminates abnormally, the host computer HMI resets the communication request; if the number of retries exceeds 3, the host computer HMI displays an error message; when communication terminates normally, the corresponding temperature control data is processed according to the TCP / IP communication protocol.

[0062] like Figure 6 As shown, this embodiment of the invention further provides a control method based on the temperature control system for semiconductor furnace tube equipment as described above, including internal and external temperature PID parameter tuning, writing the proportional coefficient R of the mixed temperature control mode, changing the cascade temperature control mode, and constant temperature zone debugging.

[0063] Based on the characteristics of hybrid temperature control mode (fast heating rate but long temperature stabilization time to reach target temperature) and cascade temperature control mode (short temperature stabilization time to target temperature but slow heating rate), a combination of hybrid and cascade temperature control modes is adopted for temperature control. Within the same heating time, the hybrid temperature control mode has a significant advantage in heating rate compared to the cascade temperature control mode. When the difference between the initial process temperature and the target process temperature T0 is large, the hybrid temperature control mode can quickly narrow the gap between the actual detected temperature and the target process temperature T0. When the difference between the actual detected temperature and the target process temperature T0 is small, the cascade temperature control mode can quickly stabilize the actual detected temperature near the target process temperature T0 with good temperature control accuracy. Therefore, the method of first using the hybrid temperature control mode and then switching to the cascade temperature control mode is chosen for furnace temperature control.

[0064] By using PID self-tuning or manual programming, optimal PID parameters are determined for both hybrid and cascade temperature control modes, ensuring good static stability of both internal and external temperatures. Considering the diverse processes involved in semiconductor furnace tube equipment, and the differences in initial and target temperatures across various process menus, the switching between hybrid and cascade temperature control modes is not based on a specific temperature value, but rather on a temperature proportionality coefficient k0. The calculation of the temperature proportionality coefficient k0 involves first determining the temperature difference T1 between the target process temperature T0 and the initial process temperature, and then calculating the temperature difference T2 between the actual detected temperature and the initial process temperature during the heating process. The ratio of T2 to T1 is the temperature proportionality coefficient k0. The closer the temperature proportionality coefficient k0 is to 1, the closer the actual detected temperature in the mixed temperature control mode is to the process target temperature T0. Considering the large lag in the internal temperature control of the furnace, the closer the temperature proportionality coefficient k0 is to 1, the closer the actual detected temperature will be to the process target temperature T0 after switching to the cascade temperature control mode, resulting in overshoot. Furthermore, the time required for the furnace temperature to cool down to the process target temperature T0 after overshoot is relatively long. Therefore, the temperature proportionality coefficient k0 is set to 0.8 when switching between the mixed temperature control mode and the cascade temperature control mode.

[0065] To further improve the furnace heating rate, certain requirements are placed on the proportionality coefficient R under the mixed temperature control mode. When the proportionality coefficient R is larger, the proportion of the external thermocouple's detection value to the mixed value is smaller, the mixed value is smaller, and the difference between the mixed value and the process target temperature T0 is larger. This results in a greater output heating power from the temperature controller, further improving the furnace heating rate.

[0066] The proportionality coefficient R is a parameter that varies with the actual detection temperature, and its value ranges from [0,1]. Considering that the temperature proportionality coefficient k0 also varies with the actual detection temperature, and that k0 effectively reflects the degree to which the hybrid temperature control mode changes with the detection temperature, the value of the hybrid model proportionality coefficient R is highly correlated with the temperature proportionality coefficient k0. When the temperature proportionality coefficient k0 is 0, the initial value of the hybrid mode proportionality coefficient R0 is 1, and the hybrid mode proportionality coefficient R and the temperature proportionality coefficient k0 satisfy the following linear relationship:

[0067] R = R0 - 1.25 * k0

[0068] The value of R0 is 1, and the value of k0 is in the range of [0, 0.8].

[0069] At the initial t0 moment when the process target temperature T0 is issued from the process menu of the host computer human-machine interface, the lower computer PLC program switches the temperature control mode of the temperature controller 7 to the mixed temperature control mode and writes the proportional coefficient R0 of the mixed temperature control mode to the temperature controller 7. When the lower computer PLC program detects that the temperature proportional coefficient k0 is 0.8, it writes the proportional coefficient R of the last mixed temperature control mode to the temperature controller 7.

[0070] When the furnace body temperature rises to time t1 (i.e., when the temperature proportional coefficient k0 is 0.8), the lower-level PLC program switches the temperature controller to cascade temperature control mode, so that the temperature of each temperature zone of the furnace body can be quickly stabilized to the process target temperature T0.

[0071] Finally, by adjusting the set temperatures of each temperature zone, the axial temperature field within the target section is kept constant (the standard deviation of the temperature at each axial point meets the requirements). At time t2, the constant temperature zone adjustment of the internal temperature zone of the furnace is carried out.

[0072] The molded case circuit breaker 1, AC contactor 2, fuse 3, and over-temperature alarm instrument 10 of this invention can form a safety interlock circuit for the temperature control system. In the event of current overload or over-temperature in any temperature zone, the furnace heating circuit is immediately cut off. The process menu of the host computer 9 can flexibly set different heating times. The programmable controller 8 switches between the mixed temperature control mode and the cascade temperature control mode of the temperature controller 7 to achieve rapid furnace heating. The process menu of the host computer 9 can flexibly set different proportional coefficients for the mixed temperature control mode, which are sent to the temperature controller 7 via the programmable controller 8 to ensure the fastest furnace heating rate under the mixed temperature control mode. The entire temperature control system only requires setting the important heating time and the proportional coefficient of the mixed temperature control mode in the process menu of the host computer's human-machine interface. The operation is convenient and can accurately meet the temperature field requirements for rapid reactions between process products and different types of special chemical materials.

[0073] The temperature control system of this invention is applicable to various semiconductor furnace tube equipment. By switching between the proportional control mode and the cascade control mode, it enables the process product to rapidly heat up inside the furnace tube and quickly stabilize at the process target temperature. It can meet the temperature field requirements for rapid reactions between process products and different types of specialty chemical materials; it has high temperature control accuracy, small fluctuations in the process target temperature, and good stability.

[0074] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A control method for a temperature control system of a semiconductor furnace tube equipment, characterized in that, The temperature control system for semiconductor furnace tube equipment includes a three-phase electric furnace transformer (4), a power regulator (5), a heating furnace body (6), a temperature controller (7), a programmable controller (8), and a host computer (9); the three-phase electric furnace transformer (4), the power regulator (5), the heating furnace body (6), the temperature controller (7), the programmable controller (8), and the host computer (9) are connected in sequence; the temperature controller (7) is also connected to the power regulator (5); The three-phase electric furnace transformer (4) is used to transform the primary side voltage and current through electromagnetic induction and continuously output the secondary side voltage and current to the power regulator (5). The power regulator (5) is used to adjust the output current from the secondary side of the three-phase electric furnace transformer (4) by receiving the heating power output signal from the temperature controller (7); The heating furnace body (6) is used to heat the process products loaded inside and to feed back the internal and external thermocouple signals to the temperature controller (7). The temperature controller (7) is used to receive the internal and external thermocouple signals fed back by the heating furnace body (6), calculate the heating output power value of each temperature zone based on the temperature values ​​detected by the internal and external thermocouples, and then send the heating output power value to the power regulator (5). The host computer (9) is used to send the target temperature parameters of the process menu to the programmable controller (8) and to receive the feedback value from the programmable controller (8); The control method includes the following steps: Obtain the target process temperature, initial process temperature, and actual process temperature; The temperature proportionality coefficient is obtained based on the target process temperature, the initial process temperature, and the actual process temperature. The temperature proportionality coefficient is compared with a preset value. If the temperature proportionality coefficient is greater than the preset value, a hybrid temperature control mode is used for temperature control; otherwise, a cascade temperature control mode is used for temperature control.

2. The control method according to claim 1, characterized in that, The formula for obtaining the temperature proportionality coefficient k0 based on the target process temperature T0, the initial process temperature, and the actual process temperature is as follows: k0 = (actual process temperature - initial process temperature) / (T0 - initial process temperature).

3. The control method according to claim 2, characterized in that, In the mixed temperature control mode, the proportional coefficient R of the mixed temperature control mode is adjusted in real time according to the temperature proportional coefficient k0; where the proportional coefficient R is proportional to the heating power.

4. The control method according to claim 3, characterized in that, The specific process of adjusting the proportional coefficient R in real time based on the temperature proportional coefficient k0 is as follows: The proportionality coefficient R and the temperature proportionality coefficient k0 satisfy the following linear relationship: The value of R0 is 1.

5. The control method according to claim 4, characterized in that, The value range of k0 is [0, 0.8].

6. The control method according to any one of claims 1-5, characterized in that, It also includes a protection unit located between the three-phase electric furnace transformer (4) and the three-phase power supply; the protection unit includes a molded case circuit breaker (1), an AC contactor (2) and a fuse (3); the molded case circuit breaker (1), the AC contactor (2) and the fuse (3) are connected in sequence.

7. The control method according to any one of claims 1-5, characterized in that, It also includes an over-temperature alarm instrument (10), which is connected to the heating furnace body (6) and the programmable controller (8) respectively, and is used to cut off the furnace heating circuit when the temperature exceeds the instrument setting temperature in each temperature zone.

8. The control method according to any one of claims 1-5, characterized in that, The heating furnace body (6) includes a heating unit (601) and each thermocouple acquisition unit (602). The heating unit (601) is used to heat the process products loaded inside according to the process menu on the host computer (9), and feeds back the internal and external thermocouple output signals and over-temperature thermocouple signals to the temperature controller (7) and over-temperature alarm instrument (10) through each thermocouple acquisition unit (602).

9. The control method according to claim 8, characterized in that, The thermocouple acquisition unit (602) includes external furnace thermocouples and internal furnace thermocouples.

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