A dual-temperature-zone wafer heater temperature control system and control method

Abstract

The application discloses a kind of double-temperature-zone wafer heater temperature control system and control method, the system includes wafer heater, main unit, measuring unit and control unit.Wafer heater contains inner zone heating disc and outer zone heating disc;Measuring unit contains temperature measuring device and voltage current measuring device;Control unit is based on the heating temperature of inner resistance wire and the voltage current value of inner heating circuit to derive resistance temperature coefficient, combined with the voltage current value of outer heating circuit to calculate the heating temperature of outer resistance wire, and then adjust the on-off of corresponding relay to control the temperature of two zones.Control method includes: obtaining the heating temperature of inner resistance wire and the voltage current value of inner and outer heating circuit;Based on the above data, derive the resistance temperature coefficient of inner resistance wire and the heating temperature of outer resistance wire;The application realizes the double-temperature-zone heating control problem of only being equipped with single-temperature-zone temperature measuring sensor, realizes the accurate measurement and control of inner and outer temperature zones of wafer heater.

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:

[0006] A dual-temperature zone wafer heater temperature control system, comprising:

[0007] 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;

[0008] 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;

[0009] 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;

[0010] 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.

[0011] 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;

[0012] 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.

[0013] Furthermore, the control unit includes a first decoupling module and a second decoupling module;

[0014] 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.

[0015] Furthermore, the main unit further includes:

[0016] a contactor connected in series to the inner heating circuit and the outer heating circuit;

[0017] 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.

[0018] 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;

[0019] (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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] Further, the control unit is configured to: based on the heating temperature of the inner resistance wire and the voltage and current values of the inner heating circuit, derive the real-time resistance of the inner resistance wire, and derive the resistance temperature coefficient of the inner resistance wire through the formula R 内 =R 0内 *[1+α(T 内 -T0)], wherein R 0内 is the resistance of the inner resistance wire at 0℃, R 内 is the real-time resistance of the inner resistance wire, T 内 is the heating temperature of the inner resistance wire, and T0 is the reference temperature;

[0024] based on the voltage and current values of the outer heating circuit, derive the real-time resistance of the outer resistance wire, combine the resistance temperature coefficient of the inner resistance wire, and inversely calculate the heating temperature of the outer resistance wire through the formula R 外 =R 0外 *[1+α(T 外 -T0)], wherein R 0外 is the resistance of the outer resistance wire at 0℃, R 外 is the real-time resistance of the outer resistance wire, T 外 is the heating temperature of the outer resistance wire, and T0 is the reference temperature. In the present application, T0 is the reference temperature, and is 0℃, which is consistent with the corresponding temperature of R 0内 and R 0外 .

[0025] The present application also provides a temperature control method of a dual-temperature-zone wafer heater, comprising the following steps:

[0026] Step S1: obtaining the heating temperature of the inner resistance wire, and obtaining the voltage and current values of the inner heating circuit and the outer heating circuit;

[0027] Step S2: based on the heating temperature of the inner resistance wire and the voltage and current values of the inner heating circuit, deriving the resistance temperature coefficient of the inner resistance wire; based on the voltage and current values of the outer heating circuit, combining the resistance temperature coefficient, and deriving the heating temperature of the outer resistance wire;

[0028] Step S3: based on the heating temperature of the inner resistance wire, adjusting the on-off of the first relay to control the temperature of the inner-zone heating disc, and based on the heating temperature of the outer resistance wire, adjusting the on-off of the second relay to control the temperature of the outer-zone heating disc.

[0029] The present application has the following beneficial effects:

[0030] 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 a dual-zone wafer heater that only a temperature measuring device can be provided 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.

[0031] 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

[0032] 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;

[0033] 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;

[0034] 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.

[0035] 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.

[0036] Description of reference numerals:

[0037] 1, wafer heater; 2, inner resistance wire; 3, outer resistance wire; 4, power supply; 5, first relay; 6, second relay; 7, inner heating circuit; 8, outer 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 radio frequency filter; 17, second radio frequency filter; 18, temperature sensing module; 19, signal transmission module; 20, current sensor; 21, signal conversion module. DETAILED DESCRIPTION

[0038] The application will be further described in conjunction with the drawings and relevant knowledge, and a clear and complete description will be made. Obviously, the described application is only a part of the embodiments of the application, not all embodiments.

[0039] The dual-temperature-zone wafer heater is usually integrated with electrostatic chucking function (such as ECHUCK), which leads to an extremely compact internal space. In order to realize the heating and chucking functions in the limited space, the structural design of the heater needs to be highly integrated, and only one temperature measuring device can be accommodated. Since the inner zone heating disc is the core reference area of temperature control (traditionally, the basic closed-loop control is realized through the inner zone temperature), the temperature measuring device is preferentially installed in the inner zone heating disc to ensure the direct monitoring of the inner zone temperature. The outer zone heating disc cannot additionally arrange the temperature measuring device due to the limited space. In addition, in the semiconductor manufacturing process, the sealing performance and assembly precision of the equipment are extremely high (for example, it needs to adapt to the vacuum plasma environment), and the installation of the temperature measuring device needs to reserve the interface and ensure the sealing performance, and too many interfaces will increase the risk of sealing failure. As the core temperature control area, the installation of the temperature measuring device of the inner zone heating disc has met the basic sealing and assembly requirements, and if the temperature measuring device is additionally arranged in the outer zone, it will destroy the sealing performance and assembly precision of the existing structure.

[0040] The temperature of the inner zone heating disc can be directly collected because, as the core temperature control area, it is preferentially allocated with limited space and hardware resources (temperature measuring device) in the structural design. The outer zone heating disc cannot directly install the temperature measuring device due to the compact structure of the equipment, strict sealing requirements, and limitations of traditional design. Moreover, with the industry trend of continuously increasing wafer size (such as from 8 inches to 12 inches or even larger) and increasingly stringent requirements for temperature uniformity in manufacturing processes (such as the film thickness deviation requirement from ±3% to ±1%), the temperature out of control caused by the inability to directly measure the temperature of the outer zone in the existing technology seriously affects the yield of chip manufacturing in advanced processes (such as 5nm, 3nm process nodes).

[0041] Therefore, the present application breaks through this hardware limitation by indirectly calculating the temperature of the outer zone (using the resistance temperature coefficient and electrical parameters), and realizes the precise control of the temperature of the outer zone.

[0042] The present invention will be further described in detail below with reference to the accompanying drawings.

[0043] Reference Figure 1 As shown, in one embodiment of the present invention, a dual-temperature zone wafer heater temperature control system is provided, comprising:

[0044] 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.

[0045] 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.

[0046] 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;

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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".

[0054] 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.

[0055] 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.

[0056] 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.

[0057] In one embodiment of the present invention, the composite control of feedforward decoupling + feedback compensation is specifically as follows:

[0058] 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).

[0059] 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℃.

[0060] 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.

[0061] 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.

[0062] The contactor 13 is connected in series with the inner heating circuit 7 and the outer heating circuit 8, and 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, and ensures effective transmission of the control signal. The control unit 9 controls the on-off of the contactor 13 according to the temperature state of the inner and outer heating plates, and realizes active safety protection based on temperature abnormalities. When the inner and outer heating plates have temperature overrunning, temperature rising too fast and other dangerous conditions, the control unit 9 can quickly cut off the contactor 13 through the control output device 15, and stop the power supply of the entire heating circuit, so as to avoid further expansion of the temperature abnormality and cause damage to the heater or process failure, and significantly improve the safety protection capability of the system, and ensure the stability and safety of the wafer heating process.

[0063] Further, the contactor 13 and the power supply 4 are further provided with a circuit breaker 14. The circuit breaker 14 is arranged between the contactor 13 and the power supply 4, and serves as an overcurrent and short-circuit protection device of the circuit, which can be quickly disconnected when abnormal current occurs in the circuit, so as to avoid damage to the power supply 4, the heating circuit and the heater caused by overcurrent or short circuit. The circuit breaker 14 is used for quickly disconnecting when overcurrent, short circuit and other abnormalities occur in the circuit, so as to protect the safety of the power supply 4 and the heating circuit.

[0064] In an embodiment of the present application, the control unit 9 is configured to: 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, output a circuit breaking control signal to the control output device 15 to control the contactor 13 to be disconnected through the control output device 15; (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 has a temperature rising rate in a unit time that exceeds a preset rate; (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.

[0065] The configuration clearly defines the specific temperature abnormality triggering condition for the disconnection of the contactor 13, and forms a multi-dimensional safety protection logic. When overtemperature occurs, timely cutting off the power supply can avoid damage to the heater due to excessively high temperature, and prevent the performance degradation of the wafer caused by high temperature. For the protection of the excessively fast temperature rising rate, the abnormal temperature rising trend of the heating system can be quickly responded, and the potential overheating risk can be avoided in advance. The limitation of the excessively large temperature difference between the inner and outer zones can prevent the risk of ceramic chuck fracture of the heater integrated with an electrostatic chuck caused by excessively large temperature difference. The three protection mechanisms complement each other, cover the static (overtemperature), dynamic (temperature rising rate) and cooperative (temperature difference) risks of temperature abnormalities, realize the all-round protection of the heater and the wafer through the active judgment of the control unit 9 and the timely disconnection of the contactor 13, and significantly improve the safety and process stability of the system operation, so as to meet the stringent requirements of wafer processing on the temperature environment.

[0066] In an embodiment of the present application, the main unit further comprises a first radio frequency filter 16 and a second radio frequency filter 17, which are respectively connected in series with the inner heating circuit 7 and the outer heating circuit 8 for filtering out the radio frequency waves induced by the wafer heater 1.

[0067] During the operation of the wafer heater 1, radio frequency waves may be induced due to the surrounding environment or the working characteristics of the wafer heater 1 itself. If these radio frequency waves enter the inner heating circuit 7 and the outer heating circuit 8, they will interfere with the accurate collection of the voltage and current values by the voltage and current measurement device, thereby affecting the calculation of the temperature coefficient of resistance of the inner resistance wire 2 and the derivation of the heating temperature of the outer resistance wire 3. The first radio frequency filter 16 and the second radio frequency filter 17 respectively filter out the radio frequency waves for the inner heating circuit 7 and the outer heating circuit 8, which can effectively eliminate the influence of radio frequency interference on the measurement of electrical parameters, ensure the accuracy of the voltage and current data, and guarantee the precision and stability of the dual-temperature-zone temperature control, thereby meeting the high requirements of the wafer heating process on measurement accuracy and control reliability.

[0068] In an embodiment of the present application, the temperature measurement device comprises a temperature sensing module 18 and a signal transmission module 19. For example, the temperature sensing module 18 comprises 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 disc to collect the heating temperature of the inner 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.

[0069] The temperature sensing module 18 adopts various types such as thermocouples, thermistors, or infrared temperature sensors, which can be flexibly selected and adapted according to the working environment (such as temperature range and spatial limitations) of the wafer heater 1 to ensure accurate collection of the temperature of the inner zone heating disc. The signal transmission module 19 converts the analog signal into a digital signal, which reduces interference and loss during signal transmission, improves the transmission accuracy and stability of the temperature data, and enables the control unit 9 to accurately obtain the real-time temperature of the inner zone, thereby providing a reliable basis for subsequent temperature regulation (such as PWM signal duty cycle adjustment, decoupling control, etc.), guaranteeing the overall precision of the dual-temperature-zone temperature control, and meeting the high requirements of the wafer heating process on temperature measurement.

[0070] In an embodiment of the present application, the voltage and current measuring device comprises a current sensor 20 and a signal conversion module 21, the current sensor 20 is connected in series to the inner heating circuit 7 and the outer heating circuit 8, the signal conversion module 21 comprises a voltage detection interface and a current detection interface, the voltage detection interface is connected in parallel to the inner heating circuit 7 and the outer 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 inner heating circuit 7 and the outer heating circuit 8 to the control unit 9 after signal conversion.

[0071] The current sensor 20 connected in series to the circuit can accurately collect the current signals of the inner heating circuit 7 and the outer heating circuit 8, and the voltage detection interface connected in parallel to the circuit can accurately obtain the voltage signals, and the combination of the two realizes comprehensive measurement of the electrical parameters of the two circuits, providing raw data support for calculating the real-time resistance of the inner resistance wire 2 to deduce the resistance temperature coefficient and calculating the real-time resistance of the outer resistance wire 3 to deduce its temperature; the signal conversion module 21 converts the detected current and voltage signals (such as analog signals to digital signals), ensures that the signals meet the processing needs of the control unit 9, reduces distortion and interference in the transmission process, and improves the reliability of data transmission. For example, the voltage and current measuring device selects a voltage and current sensor with a measurement accuracy of not less than ±0.01%.

[0072] In an embodiment of the present application, the control unit 9 is configured to: based on the heating temperature of the inner resistance wire 2 and the voltage and current values of the inner heating circuit 7, derive the real-time resistance of the inner resistance wire 2, and derive the resistance temperature coefficient of the inner resistance wire 2 through the formula R 内 =R 0内 *[1+α(T 内 -T0)], wherein R 0内 is the resistance of the inner resistance wire 2 at 0℃, R 内 is the real-time resistance of the inner resistance wire 2, T 内 is the heating temperature of the inner resistance wire 2, and T0 is the reference temperature.

[0073] Based on the voltage and current values of the outer heating circuit 8, derive the real-time resistance of the outer resistance wire 3, combine the resistance temperature coefficient of the inner resistance wire 2, and calculate the heating temperature of the outer resistance wire 3 through the formula R 外 =R 0外 *[1+α(T 外 -T0)], wherein R 0外 is the resistance of the outer resistance wire 3 at 0℃, R 外 is the real-time resistance of the outer resistance wire 3, T 外 is the heating temperature of the outer resistance wire 3, and T0 is the reference temperature.

[0074] 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.

[0075] 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:

[0076] 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;

[0077] 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.

[0078] 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;

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

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