Temperature control system and control method for double-temperature-zone wafer heater

Abstract

The invention discloses a double-temperature-zone wafer heater temperature control system and method. The system comprises a wafer heater, a main unit, a measuring unit and a control unit. The wafer heater comprises an inner area heating disc and an outer area heating disc; the measuring unit comprises a temperature measuring device and a voltage and current measuring device; the control unit obtains a resistance temperature coefficient based on the heating temperature of the internal resistance wire and the voltage and current values of the internal heating line, calculates the heating temperature of the external resistance wire by combining the voltage and current values of the external heating line, and further adjusts the on-off of the corresponding relays to control the temperatures of the two areas. The control method comprises the following steps: acquiring the heating temperature of an internal resistance wire and voltage and current values of internal and external heating lines; obtaining the resistance temperature coefficient of the internal resistance wire and the heating temperature of the external resistance wire based on the data; according to the invention, the problem of double-temperature-zone heating control only equipped with a single-temperature-zone temperature measurement sensor is solved, and accurate measurement and control of the temperatures of the inner and outer temperature zones of the wafer heater are realized.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and in particular relates to a temperature control system and a control method for a dual-temperature zone wafer heater. Background Art

[0002] In semiconductor manufacturing processes, dual-zone wafer heaters typically include an inner heating plate and an outer heating plate, which are heated using internal internal resistance wires and external resistance wires, respectively. Because wafer heaters typically incorporate an electrostatic adsorption function, their structure is complex and their internal space is exceptionally compact, necessitating the installation of only one temperature measuring device within a dual-zone wafer heater. To meet sealing and assembly requirements, this temperature measuring device is typically installed within the inner heating plate. The temperature measuring device is used to obtain the heating temperature of the inner resistance wire, thereby implementing PID closed-loop control of the inner heating plate's temperature. The outer heating plate's temperature is typically controlled using open-loop control, which primarily controls the heating power of the outer resistance wire based on a power proportionality coefficient obtained through experimental testing.

[0003] However, due to the differences between experimental environments and actual production application environments, the temperature control of the outer zone heating plate is unreliable and the temperature control effect is poor. For example, in actual production, the wafer heater is in a vacuum plasma environment. Due to changes in gas pressure and plasma intensity, as well as aging of the equipment after long-term operation, the actual heating power required by the outer zone heating plate will change. Open-loop control cannot adjust the heating power in real time according to these changes, causing the temperature of the outer zone heating plate to deviate from the set value, affecting the uniformity and stability of the coating process, and thus affecting the quality and yield of the product. Summary of the Invention

[0004] The purpose of the present invention is to provide a dual-zone wafer heater temperature control system and control method to solve the problem of unreliable open-loop control of the temperature of the outer zone heating disk of the existing dual-zone wafer heater, to achieve precise control of the temperature of the outer zone heating disk, and to improve the quality and stability of semiconductor manufacturing processes such as coating processes.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A dual-temperature zone wafer heater temperature control system, comprising: The wafer heater comprises an inner zone heating plate and an outer zone heating plate, wherein the inner zone heating plate and the outer zone heating plate are respectively provided with an inner resistance wire and an outer resistance wire of the same material; A main unit includes a power supply, a first relay, and a second relay, wherein the power supply is electrically connected to the internal resistance wire through the first relay to form an internal heating circuit, and the power supply is electrically connected to the external resistance wire through the second relay to form an external heating circuit; The measuring unit includes a temperature measuring device and a voltage and current measuring device; the temperature measuring device is provided on the inner zone heating disk and is used to obtain the heating temperature of the inner resistance wire; the voltage and current measuring device is electrically connected to the inner heating circuit and the outer heating circuit and is used to obtain the voltage and current values ​​of the inner heating circuit and the outer heating circuit; A control unit is electrically connected to the first relay, the second relay and the measuring unit; the control unit is configured to: derive the resistance temperature coefficient of the inner resistance wire based on the heating temperature of the inner resistance wire and the voltage and current values ​​of the inner heating circuit; derive the heating temperature of the outer resistance wire based on the voltage and current values ​​of the outer heating circuit in combination with the resistance temperature coefficient; adjust the on-off of the first relay based on the heating temperature of the inner resistance wire to control the temperature of the inner zone heating disk, and adjust the on-off of the second relay based on the heating temperature of the outer resistance wire to control the temperature of the outer zone heating disk.

[0006] Furthermore, the main unit further includes a PWM output device, and the control unit is electrically connected to the first relay and the second relay via the PWM output device; The control unit is configured to: based on the heating temperature of the inner resistance wire, output PWM signals with different duty cycles through the PWM output device to adjust the on-off time of the first relay, thereby controlling the temperature of the inner zone heating plate; based on the heating temperature of the outer resistance wire, output PWM signals with different duty cycles through the PWM output device to adjust the on-off time of the second relay, thereby controlling the temperature of the outer zone heating plate.

[0007] Furthermore, the control unit includes a first decoupling module and a second decoupling module; The first decoupling module is configured to: calculate a first interference amount of the heating temperature of the internal resistance wire on the external resistance wire, and reversely superimpose the first interference amount to adjust the PWM signal output by the PWM output device, thereby adjusting the on-off time of the second relay; the second decoupling module is configured to: calculate a second interference amount of the heating temperature of the external resistance wire on the internal resistance wire, and reversely superimpose the second interference amount to adjust the PWM signal output by the PWM output device, thereby adjusting the on-off time of the first relay.

[0008] Furthermore, the main unit further includes: a contactor connected in series to the inner heating circuit and the outer heating circuit; A control output device, the control unit is electrically connected to the contactor through the control output device; the control unit is configured to: output a control signal to the control output device based on the heating temperature of the inner resistance wire and / or the heating temperature of the outer resistance wire, so as to control the on and off of the contactor through the control output device.

[0009] Further, the control unit is configured to: when the heating temperature of the inner resistance wire and / or the heating temperature of the outer resistance wire satisfies at least one of the following conditions, output a circuit breaker control signal to the control output device to control the contactor to be disconnected through the control output device; (1) the heating temperature of the inner resistance wire and / or the heating temperature of the outer resistance wire exceeds a preset temperature; (2) the heating temperature of the inner resistance wire and / or the heating temperature of the outer resistance wire has a temperature rise rate exceeding a preset rate per unit time; (3) the difference between the heating temperature of the inner resistance wire and the heating temperature of the outer resistance wire is greater than a preset difference.

[0010] Furthermore, the main unit also includes a first radio frequency filter and a second radio frequency filter, and the first radio frequency filter and the second radio frequency filter are respectively connected in series to the internal heating circuit and the external heating circuit to filter out the radio frequency waves induced by the wafer heater.

[0011] Furthermore, the temperature measuring device includes a temperature sensing module and a signal transmission module. The temperature sensing module is arranged in the inner zone heating plate to collect the heating temperature of the internal resistance wire and generate a corresponding analog signal. The signal transmission module is electrically connected to the temperature sensing module to convert the analog signal into a digital signal and transmit it to the control unit.

[0012] Furthermore, the voltage and current measuring device includes a current sensor and a signal conversion module, the current sensor is connected in series to the internal heating circuit and the external heating circuit, the signal conversion module includes a voltage detection interface and a current detection interface, the voltage detection interface is connected in parallel to the internal heating circuit and the external heating circuit through a wire, and the current detection interface is electrically connected to the current sensor through a wire; the signal conversion module is configured to: transmit the detected current and voltage values ​​of the internal heating circuit and the current and voltage values ​​of the external heating circuit to the control unit after signal conversion.

[0013] Furthermore, the control unit is configured to: obtain the real-time resistance of the internal resistance wire based on the heating temperature of the internal resistance wire and the voltage and current values ​​of the internal heating circuit, and calculate the real-time resistance of the internal resistance wire by formula R 内 =R 0内 *[1+α(T 内 -T0)] to obtain the resistance temperature coefficient α of the internal resistance wire, where R0内 is the resistance of the internal resistance wire at 0°C, R 内 is the real-time resistance of the internal resistance wire, T 内 is the heating temperature of the internal resistance wire, and T0 is the reference temperature; Based on the voltage and current values ​​of the external heating circuit, the real-time resistance of the external resistance wire is obtained, combined with the resistance temperature coefficient of the internal resistance wire, and the formula R 外 =R 0外 *[1+α(T 外 -T0)] inversely calculate the heating temperature of the external resistance wire, where R 0外 is the resistance of the external resistance wire at 0°C, R 外 is the real-time resistance of the external resistance wire, T 外 is the heating temperature of the external resistance wire, and T0 is the reference temperature. In the present invention, T0 is the reference temperature, which is 0°C and has the same value as R 0内 、R 0外 The corresponding temperature is consistent.

[0014] The present invention also provides a temperature control method for a dual-temperature zone wafer heater, comprising the following steps: Step S1: obtaining the heating temperature of the internal resistance wire, and obtaining the voltage and current values ​​of the internal heating circuit and the external heating circuit; Step S2: deriving the resistance temperature coefficient of the inner resistance wire based on the heating temperature of the inner resistance wire and the voltage and current values ​​of the inner heating circuit; and deriving the heating temperature of the outer resistance wire based on the voltage and current values ​​of the outer heating circuit in combination with the resistance temperature coefficient; Step S3: adjusting the on-off of the first relay based on the heating temperature of the inner resistance wire to control the temperature of the inner zone heating plate, and adjusting the on-off of the second relay based on the heating temperature of the outer resistance wire to control the temperature of the outer zone heating plate.

[0015] The present invention has the following beneficial effects: The present invention solves the problem of dual-zone heating control when only a single-zone temperature measuring device is provided. The structural limitation of dual-zone wafer heaters, which can only be equipped with a temperature measuring device in the inner zone, simplifies the structural design and adapts to compact space scenarios. No additional outer zone temperature measuring device is required. External zone temperature monitoring can be achieved solely through electrical parameter measurement and algorithm derivation. This makes it perfectly compatible with compact wafer heaters with integrated electrostatic adsorption functions, thereby improving the temperature control performance of the inner and outer zone heating plates without increasing hardware complexity. At the same time, thanks to the independent temperature control mechanisms of the inner and outer zone heating plates, the temperatures of the inner and outer zone heating plates can be independently set and highly precisely controlled within the allowable temperature difference range, meeting the differentiated temperature requirements for different zones in the coating process, providing strong support for the stable implementation of the coating process, and ultimately achieving the ideal coating uniformity effect.

[0016] The precise measurement of the temperature of the outer zone heating plate is based on the physical property that the resistivity of the resistance wire changes with temperature. This ensures the reliability of the temperature control of the outer zone heating plate, avoids the error caused by the experimental fitting power proportional coefficient, and makes the temperature of the outer zone heating plate more in line with the actual working conditions, thereby ensuring the uniformity and stability of the coating process. Specifically, by real-time acquisition of the voltage and current parameters of the inner and outer heating circuits where the inner and outer zone heating plates are located, as well as real-time acquisition of the heating temperature of the inner resistance wire, combined with the temperature coefficient of resistance (TCR) to infer the heating temperature of the outer resistance wire, a precise closed-loop control system for the temperature of the outer zone heating plate is constructed to solve the problem of insufficient accuracy of traditional open-loop control; in addition, the control unit realizes independent control of the heating power of the inner and outer resistance wires by adjusting the on and off of the first and second relays respectively, realizes independent adjustment of dual-temperature zone heating, and improves process flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of a circuit for a dual-temperature zone wafer heater temperature control system according to one embodiment of the present invention; Figure 2 Schematic diagram of the control principle of a dual-temperature zone wafer heater temperature control system according to one embodiment of the present invention; Figure 3 Schematic diagram of the control principle of a dual-temperature zone wafer heater temperature control system in a decoupled state according to an embodiment of the present invention.

[0018] Figure 4 The figure is a flow chart of a temperature control method for a dual-temperature zone wafer heater according to an embodiment of the present invention.

[0019] Description of reference numerals: 1. Wafer heater; 2. Internal resistance wire; 3. External resistance wire; 4. Power supply; 5. First relay; 6. Second relay; 7. Internal heating circuit; 8. External heating circuit; 9. Control unit; 10. PWM output device; 11. First decoupling module; 12. Second decoupling module; 13. Contactor; 14. Circuit breaker; 15. Control output device; 16. First RF filter; 17. Second RF filter; 18. Temperature sensing module; 19. Signal transmission module; 20. Current sensor; 21. Signal conversion module. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the accompanying drawings and related knowledge, and described clearly and completely. Obviously, the described applications are only part of the embodiments of the present invention, rather than all of the embodiments.

[0021] Dual-zone wafer heaters typically incorporate an electrostatic adsorption function (such as the ECHUCK), resulting in an exceptionally compact internal footprint. To achieve both heating and adsorption functions within this limited space, the heater's structural design requires a high degree of integration, accommodating only a single temperature measuring device. Since the inner heating plate serves as the core reference area for temperature control (traditionally, this temperature is used for basic closed-loop control), the temperature measuring device is primarily installed within the inner heating plate to ensure direct monitoring of the inner zone's temperature. Space constraints prevent the placement of an additional temperature measuring device on the outer heating plate. Furthermore, semiconductor manufacturing processes place extremely high demands on equipment sealing and assembly precision (for example, to withstand vacuum plasma environments). Therefore, the installation of a temperature measuring device requires pre-reserved interfaces and guaranteed sealing performance. Excessive interfaces increase the risk of seal failure. The inner heating plate, as the core temperature control area, already meets basic sealing and assembly requirements. Adding a temperature measuring device to the outer zone would compromise the sealing and assembly precision of the existing structure.

[0022] The inner heating plate's temperature can be directly measured because, as the core temperature control area, it is prioritized in the structural design for limited space and hardware resources (temperature measurement devices). However, the outer heating plate cannot be directly equipped with a temperature measurement device due to its compact structure, strict sealing requirements, and traditional design limitations. Furthermore, with the industry trend of increasing wafer sizes (e.g., from 8 inches to 12 inches and even larger) and increasingly stringent temperature uniformity requirements in manufacturing processes (e.g., increasing film thickness deviation requirements from ±3% to ±1%), the inability to directly measure the outer zone's temperature with existing technology, resulting in temperature runaway, severely impacts chip manufacturing yields in advanced process nodes (e.g., 5nm and 3nm).

[0023] Therefore, the present invention breaks through this hardware limitation by indirectly calculating the temperature of the external zone (using the resistance temperature coefficient and electrical parameters) and realizes precise control of the temperature of the external zone.

[0024] The present invention will be further described in detail below with reference to the accompanying drawings.

[0025] Reference Figure 1 As shown, in one embodiment of the present invention, a dual-temperature zone wafer heater temperature control system is provided, comprising: The wafer heater 1 includes an inner zone heating plate and an outer zone heating plate, each of which is provided with an inner resistance wire 2 and an outer resistance wire 3 made of the same material. The inner resistance wire 2 and the outer resistance wire 3 are made of the same material to ensure that they have consistent resistance-temperature characteristics, such as resistance temperature coefficient, to avoid temperature calculation deviations caused by material differences and to ensure accurate temperature control of the outer zone heating plate. The main unit includes a power supply 4, a first relay 5, and a second relay 6. The power supply 4 is electrically connected to the inner resistance wire 2 through the first relay 5 to form an inner heating circuit 7. The power supply 4 is electrically connected to the outer resistance wire 3 through the second relay 6 to form an outer heating circuit 8. Independent relays control the on / off of the inner heating circuit 7 and the outer heating circuit 8 to achieve separate control of the temperatures of the inner and outer heating disks, thereby flexibly adjusting the heating state according to the target temperature requirements of different heating disks. The measuring unit includes a temperature measuring device and a voltage and current measuring device; the temperature measuring device is provided on the inner zone heating plate and is used to obtain the heating temperature of the inner resistance wire 2; the voltage and current measuring device is electrically connected to the inner heating circuit 7 and the outer heating circuit 8 and is used to obtain the voltage and current values ​​of the inner heating circuit 7 and the outer heating circuit 8; the heating temperature of the inner resistance wire is obtained only by the temperature measuring device, thereby reducing the occupation of the compact space of the wafer heater; at the same time, the electrical parameters of the inner and outer heating circuits are obtained by the voltage and current measuring device, providing data support for calculating the resistance temperature coefficient of the inner resistance wire 2 and the temperature of the outer resistance wire 3; The control unit 9 is electrically connected to the first relay 5, the second relay 6, and the measuring unit. The control unit 9 is configured to: determine the resistance temperature coefficient of the inner resistance wire 2 based on the heating temperature of the inner resistance wire 2 and the voltage and current values ​​of the inner heating circuit 7; determine the heating temperature of the outer resistance wire 3 based on the voltage and current values ​​of the outer heating circuit 8 in combination with the resistance temperature coefficient; adjust the on-off of the first relay 5 based on the heating temperature of the inner resistance wire 2 to control the temperature of the inner zone heating plate, and adjust the on-off of the second relay 6 based on the heating temperature of the outer resistance wire 3 to control the temperature of the outer zone heating plate. By calculating the resistance temperature coefficient of the inner resistance wire 2 and inferring the heating temperature of the outer resistance wire 3, indirect and precise control of the temperature of the outer zone heating plate is achieved, so that the temperatures of both the inner and outer zone heating plates can form a closed-loop control; by adjusting the on-off of the relay based on the measured temperature, the heating state can be dynamically corrected to ensure that the temperatures of the inner and outer zone heating plates are stable at the target values, thereby improving the temperature uniformity and process stability of the wafer coating process.

[0026] In one embodiment of the present invention, reference Figure 1 As shown, the main unit also includes a PWM output device 10, and the control unit 9 is electrically connected to the first relay 5 and the second relay 6 through the PWM output device 10; the control unit 9 is configured to: based on the heating temperature of the inner resistance wire 2, output PWM signals with different duty cycles through the PWM output device 10 to adjust the on-off time of the first relay 5, thereby controlling the temperature of the inner zone heating plate; based on the heating temperature of the outer resistance wire 3, output PWM signals with different duty cycles through the PWM output device 10 to adjust the on-off time of the second relay 6, thereby controlling the temperature of the outer zone heating plate.

[0027] Serving as a signal conversion and transmission bridge between the control unit 9 and the relay, the PWM output device 10 enables precise transmission of control signals. Compared to directly controlling the on / off switching of the relay, it converts the temperature adjustment instructions from the control unit 9 into a quantifiable PWM signal, providing a stable signal carrier for subsequent duty cycle regulation of the relay. This improves the reliability and flexibility of the control signal, and meets the signal accuracy requirements of independent temperature control for the inner and outer heating plates.

[0028] By adjusting the relay on-off time using the PWM signal's duty cycle, precise control of the heating circuit's power supply duration is achieved. For example, when the actual temperature is higher than the target temperature, the PWM signal's duty cycle can be reduced to shorten the relay's on-time and reduce heating power. When the actual temperature is lower than the target temperature, the duty cycle can be increased to extend the on-time and increase heating power. This approach significantly improves the temperature control accuracy and response speed of the inner and outer heating plates, allowing the temperature to be more stably maintained within the target range, meeting the high temperature stability requirements of the wafer coating process.

[0029] In one embodiment of the present invention, referring to Figure 2 and Figure 3 As shown, the control unit 9 includes a first decoupling module 11 and a second decoupling module 12; the first decoupling module 11 is configured to: calculate a first interference amount of the heating temperature of the internal resistance wire 2 on the external resistance wire 3, and reversely superimpose the first interference amount to adjust the PWM signal output by the PWM output device 10, thereby adjusting the on-off time of the second relay 6; the second decoupling module 12 is configured to: calculate a second interference amount of the heating temperature of the external resistance wire 3 on the internal resistance wire 2, and reversely superimpose the second interference amount to adjust the PWM signal output by the PWM output device 10, thereby adjusting the on-off time of the first relay 5.

[0030] The first decoupling module 11 counteracts the effect of the heating temperature of the inner resistance wire 2 on the temperature of the outer resistance wire 3 by reversely superimposing the interference of the heating temperature of the inner resistance wire 2 on the temperature of the outer resistance wire 3. The second decoupling module 12 similarly counteracts the interference of the heating temperature of the outer resistance wire 3 on the temperature of the inner resistance wire. This bidirectional decoupling mechanism breaks the strong coupling relationship between the two temperature zones caused by the structure and material properties, and prevents temperature fluctuations in one temperature zone from interfering with the stable control of the other temperature zone through heat conduction and other means. By indirectly correcting the on-off time of the relay by adjusting the PWM signal, pre-compensation can be performed before the temperature deviates from the target value, significantly improving the independence and accuracy of the temperature control of the two temperature zones, ensuring that the inner zone heating plate and the outer zone heating plate operate stably within their respective target temperature ranges, and further ensuring the uniformity of wafer coating.

[0031] refer to Figure 2 and Figure 3 , specifically, the general symbol definition: PID (proportional-integral-differential controller), responsible for the basic feedback regulation of a single loop, outputs the control amount according to the deviation between the set value and the feedback value, and suppresses the temperature / parameter fluctuation of a single variable; G1, G2: controlled objects, in the present invention, are the inner zone heating disk and the outer zone heating disk of the dual temperature zone respectively, the input is the control signal, and the output is the actual temperature / current and voltage parameters; G11, G22: the self-channel transfer function of the inner zone heating disk and the outer zone heating disk, which describes the influence of a single control input on its own output, such as the inner zone PID output → the temperature change of the inner zone heating disk; G12, G21: the coupling channel transfer function of the inner zone heating disk and the outer zone heating disk, which describes the interference between variables, such as the inner zone PID output → the temperature change of the outer zone heating disk, that is, the coupling of the inner zone control affecting the outer zone; : Signal superposition node, which realizes "set value - feedback value = deviation" or "control amount + decoupling compensation amount = total input".

[0032] Further, refer to Figure 2As shown in the figure; Input and Deviation Calculation: The upper and lower input lines correspond to the setpoints of the two control targets, such as the inner zone target temperature T1set and the outer zone target temperature T2set. Through the signal superposition node, the setpoint minus the feedback value (G1 / G2 output) is calculated as the deviation, which is then transmitted to the PID controller. PID Single-Loop Control: Based on the deviation, the PID controller outputs a basic control variable, such as the inner zone PID output U1_base and the outer zone PID output U2_base, which directly adjust the outputs of G1 and G2. Coupling Issues and Decoupling Compensation: Due to G12 (inner zone control → outer zone interference) and G21 (outer zone control → inner zone interference), relying solely on PID control can lead to "adjusting the inner zone to the outer zone, and vice versa" when adjusting the outer zone, resulting in coupled oscillation. Through the signal superposition node, the decoupling compensation is added to the control variable to offset the coupled interference. For example, the inner zone PID output U1_base compensates for the outer zone's own interference G21. Final Control and Output: The compensated control variable is input to G1 and G2, outputting the actual temperature / parameter, which is then fed back to the deviation node, forming a closed-loop control.

[0033] Figure 3 This is the feedforward decoupling + feedback compensation approach mentioned in this invention. The core improvement is that the decoupling modules are separated into "GB12 and GB21," reflecting the independent design of decoupling and compensation. GB12 (the second decoupling module 12): calculates the coupling interference from the outer zone to the inner zone and outputs a compensation value that is added to the inner zone control channel. GB21 (the first decoupling module 11): calculates the coupling interference from the inner zone to the outer zone and outputs a compensation value that is added to the outer zone control channel.

[0034] Differences in workflow: After PID output, it first goes through decoupling compensation of "GB12, GB21", and then superimposed with transfer functions such as "G11, G22", making the decoupling logic clearer ( Figure 2 "PID output directly participates in decoupling calculation", Figure 3 It is "PID output → decoupling compensator → re-superposition"). Decoupling idea: Identify the coupling channel (G12, G21): Model and analyze "the interference of variable A control on variable B". Design the compensation network: Calculate the compensation required to offset the interference and superimpose it on the control channel. Closed-loop feedback: Accurate control is achieved through PID + decoupling compensation. In the present invention, G1, G2 → inner / outer zone heating plate; PID → single zone temperature regulator; G12, G21 are the mutual interference channels of inner / outer zone heating, GB12, GB21 are used to calculate the compensation to offset these interferences, such as the power change in the inner zone, which affects the temperature of the outer zone through thermal radiation / heat conduction; decoupling compensation → calculate the interference of the inner zone temperature control on the outer zone in advance, and reversely compensate it to the outer zone control to offset the coupling, so that the temperature of the two zones can be independently controlled.

[0035] In one embodiment of the present invention, the composite control of feedforward decoupling + feedback compensation is specifically as follows: The first decoupling module (GB21): Calculates the interference ΔT of the inner zone temperature to the outer zone through the heat conduction model 12 =k1×(T 内 -T 外 )×t (k1 is the thermal coupling coefficient, t is time), and is reversely superimposed on the external zone PWM control signal (duty cycle correction ΔD1 = -k2×ΔT 12 ); k1 is the thermal coupling coefficient between the inner zone and the outer zone, reflecting the intensity of the interference of the temperature change of the inner zone on the temperature of the outer zone, and the unit is ℃ / (℃·s) (that is, the amount of temperature conduction from the inner zone to the outer zone per unit temperature difference and unit time). For example, k1=0.02℃ / (℃·s) means: when the temperature difference between the inner zone and the outer zone is 10℃, every second, the temperature of the outer zone will passively change by 0.02×10×1=0.2℃ due to the heat conduction / radiation of the inner zone. k2 is the conversion coefficient between the temperature interference and the PWM duty cycle correction, and the unit is % / ℃ (that is, the percentage of PWM duty cycle that needs to be corrected for every 1℃ of temperature interference). Its function is to convert the "temperature interference amount ΔT of the inner zone to the outer zone" 12 ” is converted into “duty cycle adjustment of external zone PWM signal” to achieve reverse compensation (offset interference).

[0036] Second decoupling module (GB12): Similarly calculate the interference ΔT of the outer zone to the inner zone 21 , correct the PWM duty cycle of the inner zone; feedback compensation: combining the measured temperature of the inner zone with the reverse temperature of the outer zone, through PID feedback control, the temperature fluctuation is suppressed within ±0.5℃.

[0037] The present invention does not require an external temperature measurement device. By back-calculating electrical parameters and performing dynamic calibration, it solves the temperature measurement problem in a compact space and is compatible with the ECHUCK integrated design. Dynamic decoupling: A composite control of feedforward decoupling and feedback compensation meets the temperature consistency requirements of the edge and center of large-sized wafers. Environmental adaptability: Through dynamic calibration of the resistance temperature coefficient α and anti-interference design, for example, on a 12-inch silicon wafer, the process environment is a vacuum of 5 Pa and an Ar plasma density of 5×10¹¹cm -3 Under the conditions of vacuum plasma, the long-term stability (1000 hours) is more than 4 times better than the existing technology.

[0038] In one embodiment of the present invention, the main unit also includes: a contactor 13, which is connected in series with the internal heating circuit 7 and the external heating circuit 8; a control output device 15, and the control unit 9 is electrically connected to the contactor 13 through the control output device 15; the control unit 9 is configured to: output a control signal to the control output device 15 based on the heating temperature of the internal resistance wire 2 and / or the heating temperature of the external resistance wire 3, so as to control the contactor 13 to be turned on and off through the control output device 15.

[0039] The contactor 13 is connected in series with the inner heating circuit 7 and the outer heating circuit 8, which can realize unified on-off control of the entire heating circuit. The control output device 15 serves as a signal conversion interface between the control unit 9 and the contactor 13, ensuring the effective transmission of the control signal. The control unit 9 controls the on-off of the contactor 13 according to the temperature status of the inner and outer zone heating disks, realizing active safety protection based on temperature anomalies. When the temperature of the inner and outer heating disks reaches dangerous conditions such as overheating or rapid temperature rise, the control unit 9 can quickly cut off the contactor 13 through the control output device 15, stopping the power supply of the entire heating circuit, preventing further expansion of the temperature anomaly and causing damage to the heater or process failure, significantly improving the safety protection capability of the system and ensuring the stability and safety of the wafer heating process.

[0040] Furthermore, a circuit breaker 14 is provided between the contactor 13 and the power supply 4; the circuit breaker 14 is provided between the contactor 13 and the power supply 4 as an overcurrent and short-circuit protection device for the circuit. It can be quickly disconnected when an abnormal current occurs in the circuit to prevent overcurrent or short circuit from causing damage to the power supply 4, the heating circuit and the heater. The circuit breaker 14 is used to quickly disconnect when an abnormality such as overcurrent or short circuit occurs in the circuit to protect the safety of the power supply 4 and the heating circuit.

[0041] In one embodiment of the present invention, the control unit 9 is configured to output a circuit breaker control signal to the control output device 15 to control the contactor 13 to disconnect through the control output device 15 when the heating temperature of the inner resistance wire 2 and / or the heating temperature of the outer resistance wire 3 meets at least one of the following conditions: (1) the heating temperature of the inner resistance wire 2 and / or the heating temperature of the outer resistance wire 3 exceeds a preset temperature; (2) the heating temperature of the inner resistance wire 2 and / or the heating temperature of the outer resistance wire 3 exceeds a preset rate per unit time; (3) the difference between the heating temperature of the inner resistance wire 2 and the heating temperature of the outer resistance wire 3 is greater than a preset difference.

[0042] This configuration defines the specific temperature anomaly triggering conditions for disconnecting contactor 13, forming a multi-dimensional safety protection logic. When an overtemperature condition occurs, timely power cutoff prevents heater damage due to excessive temperatures and prevents wafer performance degradation caused by high temperatures. Protection against excessively rapid temperature rise rates quickly responds to abnormal temperature increases in the heating system, preemptively mitigating potential overheating risks. Limiting the temperature difference between the inner and outer zones prevents the risk of ceramic chucks in heaters with integrated electrostatic chucks breaking due to excessive temperature differences. These three protection mechanisms complement each other, covering static (overtemperature), dynamic (temperature rise rate), and coordinated (temperature difference) temperature anomaly risks. Through active judgment by control unit 9 and timely disconnection of contactor 13, comprehensive protection for the heater and wafer is achieved, significantly improving system operational safety and process stability, meeting the stringent temperature requirements of wafer processing.

[0043] In one embodiment of the present invention, the main unit also includes a first RF filter 16 and a second RF filter 17. The first RF filter 16 and the second RF filter 17 are respectively connected in series to the internal heating circuit 7 and the external heating circuit 8 to filter out the RF waves induced by the wafer heater 1.

[0044] During operation, wafer heater 1 may induce radio frequency waves due to the surrounding environment or its own operating characteristics. If these waves enter the internal heating circuit 7 and the external heating circuit 8, they will interfere with the voltage and current measurement device's accurate acquisition of the circuit voltage and current values, thereby affecting the calculation of the resistance temperature coefficient of internal resistor 2 and the derivation of the heating temperature of external resistor 3. First and second radio frequency filters 16 and 17 filter radio frequency waves for internal heating circuit 7 and external heating circuit 8, respectively, effectively eliminating the impact of radio frequency interference on electrical parameter measurements, ensuring the accuracy of voltage and current data, and safeguarding the precision and stability of dual-zone temperature control, adapting to the high measurement accuracy and control reliability requirements of the wafer heating process.

[0045] In one embodiment of the present invention, the temperature measuring device includes a temperature sensing module 18 and a signal transmission module 19. For example, the temperature sensing module 18 includes at least one of a thermocouple, a thermistor or an infrared temperature sensor. The temperature sensing module 18 is arranged in the inner zone heating disk to collect the heating temperature of the internal resistance wire 2 and generate a corresponding analog signal. The signal transmission module 19 is electrically connected to the temperature sensing module 18 to convert the analog signal into a digital signal and transmit it to the control unit 9.

[0046] The temperature sensing module 18 adopts various types such as thermocouples, thermistors or infrared temperature sensors, and can flexibly select appropriate sensors according to the working environment of the wafer heater 1 (such as temperature range, space limitations), to ensure the accurate acquisition of the temperature of the inner zone heating plate; the signal transmission module 19 converts the analog signal into a digital signal, reducing interference and loss during signal transmission, and improving the transmission accuracy and stability of the temperature data, so that the control unit 9 can accurately obtain the real-time temperature of the inner zone, providing a reliable basis for subsequent temperature control (such as PWM signal duty cycle adjustment, decoupling control, etc.), ensuring the overall accuracy of the dual-temperature zone temperature control, and meeting the high requirements of the wafer heating process for temperature measurement.

[0047] In one embodiment of the present invention, the voltage and current measuring device includes a current sensor 20 and a signal conversion module 21. The current sensor 20 is connected in series to the internal heating circuit 7 and the external heating circuit 8. The signal conversion module 21 includes a voltage detection interface and a current detection interface. The voltage detection interface is connected in parallel to the internal heating circuit 7 and the external heating circuit 8 through a wire, and the current detection interface is electrically connected to the current sensor 20 through a wire; the signal conversion module 21 is configured to: transmit the detected current and voltage values ​​of the internal heating circuit 7 and the current and voltage values ​​of the external heating circuit 8 to the control unit 9 after signal conversion.

[0048] The current sensor 20, connected in series with the circuit, accurately captures the current signals of the internal heating circuit 7 and the external heating circuit 8. The voltage detection interface, connected in parallel with the circuit, accurately acquires the voltage signal. The combination of these two enables comprehensive measurement of the electrical parameters of both circuits, providing raw data support for calculating the real-time resistance of the internal resistor 2 to derive the resistance temperature coefficient, and for calculating the real-time resistance of the external resistor 3 to infer its temperature. The signal conversion module 21 converts the detected current and voltage signals (e.g., from analog to digital), ensuring that the signals meet the processing requirements of the signal adaptation control unit 9, reducing distortion and interference during transmission, and improving data transmission reliability. For example, the voltage and current measurement device uses a voltage and current sensor with a measurement accuracy of no less than ±0.01%.

[0049] In one embodiment of the present invention, the control unit 9 is configured to: obtain the real-time resistance of the internal resistance wire 2 based on the heating temperature of the internal resistance wire 2 and the voltage and current values ​​of the internal heating circuit 7, and calculate the real-time resistance of the internal resistance wire 2 by the formula R 内 =R 0内 *[1+α(T 内 -T0)] to obtain the resistance temperature coefficient α of the internal resistance wire 2, where R 0内 is the resistance of internal resistance wire 2 at 0℃, R 内 is the real-time resistance of the internal resistance wire 2, T 内 is the heating temperature of the internal resistance wire 2, and T0 is the reference temperature; Based on the voltage and current values ​​of the external heating circuit 8, the real-time resistance of the external resistance wire 3 is obtained, combined with the resistance temperature coefficient of the internal resistance wire 2, and the formula R 外 =R 0外 *[1+α(T 外 -T0)] inversely calculate the heating temperature of the external resistance wire 3, where R 0外 is the resistance of the external resistance wire 3 at 0°C, R 外 is the real-time resistance of the external resistance wire 3, T 外 is the heating temperature of the external resistance wire 3, and T0 is the reference temperature.

[0050] This method implements the core logic of calculating the outer zone temperature using known parameters in the inner zone. On the one hand, the resistance temperature coefficient α is calculated based on the measured inner zone temperature and voltage and current values, fully leveraging the advantage of direct inner zone temperature measurement to ensure the accuracy of α. Since the inner and outer resistance wires 2 and 3 are made of the same material, this coefficient can be directly transferred to the outer zone temperature calculation. On the other hand, after obtaining the real-time resistance using the outer zone voltage and current values, the outer zone temperature is inverted by combining α. This successfully overcomes the limitation of the dual temperature zones, which can only be equipped with a temperature measurement device in the inner zone due to the compact structure. This allows the outer zone temperature to be controlled from traditional open-loop approximate control to closed-loop precise control based on physical properties. This method avoids the errors introduced by experimentally obtaining the power proportional coefficient, significantly improving the accuracy of the outer zone temperature measurement, thereby ensuring the effectiveness of the independent temperature control of the two temperature zones and meeting the high temperature uniformity and stability requirements of the wafer coating process.

[0051] Reference Figure 4 As shown, the present invention also provides a dual-zone wafer heater temperature control method, which uses the dual-zone wafer heater temperature control system as described above and specifically includes the following steps: Step S1: obtaining the heating temperature of the internal resistance wire 2, and obtaining the voltage and current values ​​of the internal heating circuit 7 and the external heating circuit 8; In this step, by directly acquiring the heating temperature of the inner resistance wire 2, basic feedback data is provided for the closed-loop control of the temperature of the inner zone heating disk. At the same time, the voltage and current values ​​of the inner heating circuit 7 and the outer heating circuit 8 are collected, providing key electrical parameters for the subsequent calculation of the real-time resistance of the inner resistance wire 2 to deduce the resistance temperature coefficient, and the calculation of the real-time resistance of the outer resistance wire 3 to infer its heating temperature. Step S2: Based on the heating temperature of the inner resistance wire 2 and the voltage and current values ​​of the inner heating circuit 7, the resistance temperature coefficient of the inner resistance wire 2 is obtained; based on the voltage and current values ​​of the outer heating circuit 8 and the resistance temperature coefficient, the heating temperature of the outer resistance wire 3 is obtained; In this step, the resistance temperature coefficient is calculated using the known temperature and electrical parameters of the inner zone, giving full play to the advantage of direct temperature measurement in the inner zone. Since the inner resistance wire 2 and the outer resistance wire 3 are made of the same material, the coefficient can be directly used to calculate the temperature of the outer zone, solving the problem of no direct temperature measurement sensor in the outer zone. The outer zone temperature is inferred by combining the electrical parameters of the outer zone with the resistance temperature coefficient, and the outer zone temperature is converted from traditional open-loop approximate control to closed-loop precise measurement based on the resistance temperature characteristics, avoiding the error of the power proportional coefficient obtained experimentally, significantly improving the accuracy of the outer zone temperature measurement, and providing a reliable basis for precise temperature control of the outer zone.

[0052] Step S3: Based on the heating temperature of the inner resistance wire 2, the first relay 5 is turned on and off to control the temperature of the inner zone heating plate, and based on the heating temperature of the outer resistance wire 3, the second relay 6 is turned on and off to control the temperature of the outer zone heating plate.

[0053] In this step, independent closed-loop control of the two temperature zones is achieved by comparing the measured (or derived) temperatures in the inner and outer zones with the target temperatures and dynamically adjusting the on / off switching of the corresponding relays. The inner zone is regulated based on direct temperature measurement, while the outer zone is regulated based on the derived, precise temperature. This synergistic effect avoids the limitations of traditional open-loop control of the outer zone, ensuring that the temperatures in both zones remain stable within the target range. This effectively improves the accuracy and stability of the dual-zone temperature control, meeting the temperature uniformity requirements of the wafer coating process and ensuring coating quality.

[0054] Although some embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and all of these should fall within the scope of the present invention.

Claims

1. A dual-temperature zone wafer heater temperature control system, characterized in that: include: The wafer heater comprises an inner zone heating plate and an outer zone heating plate, wherein the inner zone heating plate and the outer zone heating plate are respectively provided with an inner resistance wire and an outer resistance wire of the same material; A main unit includes a power supply, a first relay, and a second relay, wherein the power supply is electrically connected to the internal resistance wire through the first relay to form an internal heating circuit, and the power supply is electrically connected to the external resistance wire through the second relay to form an external heating circuit; The measuring unit includes a temperature measuring device and a voltage and current measuring device; the temperature measuring device is provided on the inner zone heating disk and is used to obtain the heating temperature of the inner resistance wire; the voltage and current measuring device is electrically connected to the inner heating circuit and the outer heating circuit and is used to obtain the voltage and current values ​​of the inner heating circuit and the outer heating circuit; a control unit electrically connected to the first relay, the second relay, and the measuring unit; the control unit being configured to: derive a resistance temperature coefficient of the internal resistance wire based on the heating temperature of the internal resistance wire and the voltage and current values ​​of the internal heating circuit; Based on the voltage and current values ​​of the external heating circuit and combined with the resistance temperature coefficient, the heating temperature of the external resistance wire is obtained; based on the heating temperature of the internal resistance wire, the on-off of the first relay is adjusted to control the temperature of the inner zone heating disk, and based on the heating temperature of the external resistance wire, the on-off of the second relay is adjusted to control the temperature of the outer zone heating disk.

2. A dual-temperature zone wafer heater temperature control system according to claim 1, characterized in that: The main unit further includes a PWM output device, and the control unit is electrically connected to the first relay and the second relay via the PWM output device; The control unit is configured to: based on the heating temperature of the inner resistance wire, output PWM signals with different duty cycles through the PWM output device to adjust the on-off time of the first relay, thereby controlling the temperature of the inner zone heating plate; based on the heating temperature of the outer resistance wire, output PWM signals with different duty cycles through the PWM output device to adjust the on-off time of the second relay, thereby controlling the temperature of the outer zone heating plate.

3. The dual-temperature zone wafer heater temperature control system according to claim 2, characterized in that: The control unit includes a first decoupling module and a second decoupling module; The first decoupling module is configured to: calculate a first interference amount of the heating temperature of the inner resistance wire on the outer resistance wire, and reversely superimpose the first interference amount to adjust the PWM signal output by the PWM output device, thereby adjusting the on-off time of the second relay; The second decoupling module is configured to calculate a second interference amount of the heating temperature of the external resistance wire on the internal resistance wire, and reversely superimpose the second interference amount to adjust the PWM signal output by the PWM output device, thereby adjusting the on-off time of the first relay.

4. The dual-temperature zone wafer heater temperature control system according to claim 1, characterized in that: The main unit also includes: a contactor connected in series to the inner heating circuit and the outer heating circuit; A control output device, the control unit is electrically connected to the contactor through the control output device; the control unit is configured to: output a control signal to the control output device based on the heating temperature of the inner resistance wire and / or the heating temperature of the outer resistance wire, so as to control the on and off of the contactor through the control output device.

5. The dual-temperature zone wafer heater temperature control system according to claim 4, characterized in that: The control unit is configured to: when the heating temperature of the inner resistance wire and / or the heating temperature of the outer resistance wire satisfies at least one of the following conditions, output a circuit breaker control signal to the control output device, so as to control the contactor to be disconnected through the control output device; (1) The heating temperature of the inner resistance wire and / or the heating temperature of the outer resistance wire exceeds a preset temperature; (2) The heating temperature of the inner resistance wire and / or the heating temperature of the outer resistance wire has a temperature rise rate exceeding a preset rate per unit time; (3) The difference between the heating temperature of the inner resistance wire and the heating temperature of the outer resistance wire is greater than a preset difference.

6. The dual-temperature zone wafer heater temperature control system according to claim 1, characterized in that: The main unit further includes a first radio frequency filter and a second radio frequency filter, wherein the first radio frequency filter and the second radio frequency filter are respectively connected in series to the internal heating circuit and the external heating circuit, and are used to filter out radio frequency waves induced by the wafer heater.

7. The dual-temperature zone wafer heater temperature control system according to claim 1, characterized in that: The temperature measuring device includes a temperature sensing module and a signal transmission module. The temperature sensing module is arranged in the inner zone heating plate to collect the heating temperature of the internal resistance wire and generate a corresponding analog signal. The signal transmission module is electrically connected to the temperature sensing module to convert the analog signal into a digital signal and transmit it to the control unit.

8. The dual-temperature zone wafer heater temperature control system according to claim 1, characterized in that: The voltage and current measuring device includes a current sensor and a signal conversion module, the current sensor is connected in series with the inner heating circuit and the outer heating circuit, the signal conversion module includes a voltage detection interface and a current detection interface, the voltage detection interface is connected in parallel with the inner heating circuit and the outer heating circuit through a wire, and the current detection interface is electrically connected to the current sensor through a wire; The signal conversion module is configured to: transmit the detected current and voltage values ​​of the inner heating circuit and the detected current and voltage values ​​of the outer heating circuit to the control unit after signal conversion.

9. The dual-temperature zone wafer heater temperature control system according to claim 1, characterized in that: The control unit is configured to: obtain the real-time resistance of the internal resistance wire based on the heating temperature of the internal resistance wire and the voltage and current values ​​of the internal heating circuit, and calculate the real-time resistance of the internal resistance wire by formula R 内 =R 0内 *[1+α(T 内 -T0)] to obtain the resistance temperature coefficient α of the internal resistance wire, where R 0内 is the resistance of the internal resistance wire at 0°C, R 内 is the real-time resistance of the internal resistance wire, T 内 is the heating temperature of the internal resistance wire, and T0 is the reference temperature; Based on the voltage and current values ​​of the external heating circuit, the real-time resistance of the external resistance wire is obtained, combined with the resistance temperature coefficient of the internal resistance wire, and the formula R 外 =R 0外 *[1+α(T 外 -T0)] inversely calculate the heating temperature of the external resistance wire, where R 0外 is the resistance of the external resistance wire at 0°C, R 外 is the real-time resistance of the external resistance wire, T 外 is the heating temperature of the external resistance wire, and T0 is the reference temperature.

10. A temperature control method for a dual-temperature zone wafer heater, characterized in that: The temperature control method adopts the temperature control system according to any one of claims 1 to 9; The temperature control method comprises: Step S1: obtaining the heating temperature of the internal resistance wire, and obtaining the voltage and current values ​​of the internal heating circuit and the external heating circuit; Step S2: deriving the resistance temperature coefficient of the inner resistance wire based on the heating temperature of the inner resistance wire and the voltage and current values ​​of the inner heating circuit; and deriving the heating temperature of the outer resistance wire based on the voltage and current values ​​of the outer heating circuit in combination with the resistance temperature coefficient; Step S3: adjusting the on-off of the first relay based on the heating temperature of the inner resistance wire to control the temperature of the inner zone heating plate, and adjusting the on-off of the second relay based on the heating temperature of the outer resistance wire to control the temperature of the outer zone heating plate.

Images