Chemical-acoustic-thermal three-field coupling etching uniformity adaptive control method

Abstract

The application provides a chemical-acoustic-thermal three-field coupling etching uniformity self-adaptive control method, including the following steps: step S1, model construction: constructing an etching rate correlation model with chemical field parameters, acoustic field parameters and thermal field parameters as inputs and etching rates of each partition as outputs; step S2, parameter presetting and etching starting; step S3, data acquisition and rate output: acquiring state data in the etching process through a plurality of sensors belonging to the chemical field, the acoustic field and the thermal field, wherein the state data comprises characteristic parameters of the chemical field, the acoustic field and the thermal field; inputting the acquired characteristic parameters into the etching rate correlation model to output current local etching rates; step S4, deviation calculation and closed-loop adjustment; step S5, repeating steps S3-S4 until etching parameters of a workpiece reach target requirements, and terminating etching. The application realizes linkage and collaborative control of three-field parameters.

Description

Technical Field

[0001] This invention belongs to the field of wet etching technology, and particularly relates to an adaptive control method for etching uniformity coupling of chemical, acoustic and thermal three fields. Background Technology

[0002] Wet etching is a core process in optical component processing and semiconductor manufacturing. It achieves quantitative material removal through a chemical reaction between the etching solution and the workpiece surface. With mega-acoustic assistance, the etching effect can be further optimized. It is widely used in high-precision optical surface shaping, post-lithography etching of semiconductor wafers, and microstructure processing. With the rapid development of high-end optical systems and advanced semiconductor processes, increasingly stringent requirements are being placed on the uniformity, precision, batch consistency, and operational stability of wet etching, especially for large-diameter optical components and large-size wafers, where the wavefront PV degradation of 5μm wavefront must be controlled within ≤30nm. Existing wet etching control technologies have the following core shortcomings: 1. Most of them adopt a single chemical field control mode, or a single field or two field independent control mode, which cannot achieve multi-parameter linkage and coordinated adjustment; after the chemical field parameters are adjusted, the acoustic field and thermal field are not adapted synchronously, resulting in greater fluctuations in the etching rate; at the same time, the existing solutions do not have real-time feedback and dynamic adjustment during the etching process, and cannot cope with the etching rate deviation caused by the decay of the etching solution concentration.

[0003] 2. Existing etching equipment has a single sensing and monitoring dimension, which cannot achieve millisecond-level acquisition and adjustment of three field parameters; the constant temperature system cannot effectively offset the heat release of the megohmonic transducer and the heat release of the etching reaction, resulting in large temperature fluctuations of the etching solution; the frequency tracking accuracy of the megohmonic drive system is insufficient and cannot adapt to load changes in real time.

[0004] Therefore, developing an etching control method that can achieve coordinated chemical-acoustic-thermal three-field linkage, fully closed-loop adaptive adjustment, and multi-dimensional sensing and monitoring to solve the problems of poor uniformity, low consistency, insufficient accuracy, and weak operational stability of existing technologies has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide an adaptive control method for etching uniformity based on chemical-acoustic-thermal three-field coupling, achieving coordinated control of the three field parameters and replacing the traditional single-field or two-field independent adjustment modes. The technical solution adopted is as follows: An adaptive control method for etching uniformity coupled with chemical-acoustic-thermal fields includes: S1. Model Construction: Construct an etching rate correlation model with chemical field parameters, acoustic field parameters, and thermal field parameters as inputs and etching rate of each partition as output.

[0006] A chemical-acoustic-thermal three-field coupled etching rate correlation model is established. Based on the target etching requirements of the workpiece, the target etching parameters and uniformity threshold of the entire etching process are preset. The frequency, power, and matching parameters of the megasonic system, as well as the PID control gain of the drive control system (referring to the controller that adjusts the control parameters, such as the adjustment accuracy control of the megasonic generator) are adjusted according to the etching target. In step S1: The etching rate correlation model, which involves chemical-acoustic-thermal three-field coupling, is as follows: Chemical field parameters with etching solution composition and concentration, etching solution pH value, and etching solution circulation flow rate as the core; Acoustic field parameters with megaphonic frequency, megaphonic power density, sweep range, zoned sound pressure level, and transducer impedance as the core. Thermal field parameters with overall temperature of the etching solution and zoned temperature control accuracy as the core; A quantitative correlation model between the three factors and the etching rate; Data fitting was performed using simulation models derived from multiphysics simulation software such as COMSOL.

[0007] In step S1: The target etching parameters include target etching depth, target etching rate, etching uniformity deviation (etching uniformity control: the component needs to maintain high-precision wavefront indices basically unchanged at an etching depth of 5μm (wavefront PV degradation ≤30nm), and the spatial uniformity of the etching rate during the etching process needs to be strictly controlled), and upper limit of workpiece surface roughness; the etching uniformity threshold requires that the wavefront PV degradation ≤30nm after etching 5μm.

[0008] S2. Parameter Preset and Etching Start: Based on the target etching requirements of the workpiece, set the target etching rate and target etching depth, and start the etching process.

[0009] The etching solution is prepared in the etching tank, and the etching process is started according to the preset initial parameters to establish a stable chemical field, acoustic field and thermal field environment with feedback from the multi-sensor array (different detection sensors are placed in different partitions in the etching tank to form a sensor array).

[0010] In step S2: The dimensions of the etching groove are 980mm × 1000mm × 250mm; The etching process in a chemical field involves selecting the appropriate composition based on the etching element. For example, hydrofluoric acid etching solution is prepared at a concentration of 1:8 with a pH value of 2-7. In the acoustic field, the megaphonic frequency is ≥0.90MHz and the power density is ≥6W / cm². 2 The frequency sweep range is ±2kHz, and it adopts a zoned array type megaphonic transducer array, with each zone having independently adjustable power. In the thermal field, the overall temperature of the etching solution is between 20-50℃, with a temperature control accuracy of ±0.5℃. The etching tank is equipped with zoned heating and cooling units, and the temperature of each zone can be adjusted independently. At the same time, cooling pipes are used to control the heat dissipation of the megohmonic transducer (using cooling pipes to dissipate heat from the megohmonic transducer) to reduce the impact of megohmonic frequency fluctuations.

[0011] S3, Data Acquisition and Rate Output: The etching process uses multiple sensors belonging to chemical field, acoustic field and thermal field to collect state data in real time. The state data includes characteristic parameters of chemical field, acoustic field and thermal field. The collected feature parameters are input into the etching rate correlation model, and the current etching rate of each partition is output, which is recorded as the local etching rate. That is, by using multi-dimensional high-precision sensors, the status data of the entire etching process is collected in real time. The real-time etching data is compared with the target etching parameters (target etching rate) to calculate the global etching rate deviation and local etching rate deviation of etching uniformity (the etching parameters are corrected by simultaneously calculating the global etching rate and local etching rate through sensors). The data acquisition module enables real-time communication between subsystems via Modbus-TCP / IP and OPC UA protocols, with a sampling frequency of up to 1ms. The acquired data supports CSV format storage and PDF report export. Multi-dimensional high-precision sensors include temperature sensors, flow meters, pH meters, and concentration meters.

[0012] The collected real-time status data includes: Real-time temperature, concentration, pH value, and flow rate of the etching solution in the workpiece etching area; real-time frequency, power, sound field intensity, and sound field uniformity distribution data of the megaphonic system (the sound field intensity and sound pressure distribution in different areas of the etching tank are recorded by a sound pressure meter). The data from the three physical fields were used to calculate and correct the etching rate deviation.

[0013] In step S3: The PLC acquires the 0-10V voltage signal output from the megasonic generator via its internal bus and supporting modules, and collects temperature data from the flow meter, pH meter, liquid concentration meter, etching solution, and coolant. The acquired data is synchronously transmitted to the data analysis module in the PLC main control unit for analysis and processing.

[0014] Step S4, Deviation Calculation and Closed-Loop Adjustment: Based on the local etching rates, the arithmetic mean of the local etching rates is taken to obtain the global etching rate; the global etching rate is compared with the target etching rate to obtain the global etching rate deviation. The local etching rate is compared with the global etching rate region by region to obtain the deviation of the local etching rate; Based on the sign and magnitude of the aforementioned deviations, the etching rate correlation model outputs adjustment values ​​for the chemical field, acoustic field, and thermal field; the PLC main control unit adjusts the characteristic parameters of the chemical field, acoustic field, and thermal field respectively according to these adjustment values.

[0015] The etching rate of the component is controlled by adjusting the concentration, flow rate, and pH value of the etching solution in the chemical field. He controls the uniformity of interface etching by adjusting the megaphonic frequency, power density, and sweep frequency range of the sound field. The uniformity of acoustic field and chemical concentration gradient distribution is optimized; local etching rate deviations are corrected by temperature control of the thermal field, achieving three-field coupled adaptive control of etching uniformity.

[0016] (1) When the deviation between the chemical field etching rate (the etching rate of the element etched by the etching solution) and the target etching rate exceeds the threshold, the PLC adjusts the output flow rate of the circulating pump through the frequency converter. At the same time, the concentration and pH value of the etching solution are adjusted by the feedback concentration and pH value parameters to correct the etching rate to the target range. The circulating filtration system uses a 0.55kW filter pump, which automatically adjusts the flow rate within the range of 0-50L / min based on sensor signals, and the flow rate is stably controlled at 1.5-2m / s to reduce particle deposition; the high-flow circulating pump drives the acid solution to flow at high speed across the workpiece surface to eliminate local concentration differences. The fluid interface (the inlet where the circulating pump flows into the etching tank) integrates temperature, pressure, and level sensors and connects to the PLC to achieve precise control of the valve opening. The PLC uses the real-time readings from the flow meter to determine the blockage status of the circulating filter element and triggers a replacement reminder.

[0017] (2) When the particle concentration of the etching solution increases, the circulation flow rate is increased to reduce particle deposition and simultaneously trigger the filter element status monitoring of the filter pump. (3) When the etching rate of each sub-region of the whole fluctuates and the overall mass transfer is uneven, adjust the overall power density and sweep frequency range of the megohmmeter, homogenize the diffusion boundary layer of the etching interface through the cavitation effect, improve the global mass transfer uniformity, and ensure the stability of power output through PID control. (4) When a local etching rate deviation occurs in one or more sub-regions, the partition temperature and mega-acoustic power of the sub-region are adjusted accordingly. For the region with a low etching rate, the temperature (temperature adjustment step size 0.5℃) and mega-acoustic power of the region are slightly increased to improve the local etching rate. For the region with a high etching rate, the temperature and mega-acoustic power of the region are slightly decreased to reduce the local etching rate until the etching rate deviation of the region falls back to within 120nm. (5) When the sound field intensity distribution is uneven in the etching area and the overall etching rate fluctuates, the PLC adjusts the overall frequency, power density and sweep frequency range of the megohmmeter generator to improve the etching uniformity through the cavitation effect.

[0018] The megaphone drive system achieves communication and interactive control between the megaphone generator and the PLC through parallel port communication. The PID main control unit controls the hysteresis to support stepped power increases, avoiding oscillations caused by sudden changes.

[0019] During the etching process, a high-precision temperature control probe monitors the temperature of the etching solution in real time. When the temperature exceeds the threshold due to megasonic and reaction exothermic reactions, the PLC main control unit automatically triggers the cooling circuit (cooling device) to quickly remove heat through the plate heat exchanger, causing the temperature to drop and preventing the etching rate from running out of control due to temperature fluctuations.

[0020] S5. Monitor the changes in etching parameters in real time during the etching process, and automatically control and compensate for abnormal parameters; repeat steps S3-S4 until the etching parameters of the workpiece meet the target requirements, and then terminate the etching process.

[0021] In step S5: The power value of the megasonic output is compared with the expected input value in real time to monitor the status feedback of the megasonic and determine the working status and alarm status of the megasonic. Real-time monitoring of etching solution concentration and temperature; triggers multi-level audible and visual alarms when parameters exceed limits.

[0022] A chemical-acoustic-thermal three-field coupled etching system includes a PLC main control unit, a chemical field, an acoustic field, a thermal field, and a multi-dimensional sensing and acquisition module; Furthermore, the PLC main control unit is connected to multi-dimensional sensing and acquisition modules for chemical field, acoustic field, and thermal field, respectively, for executing full-process control and linkage adjustment; The chemical field includes an etching tank, a circulation pump, a filter pump, a regulating valve, a flow meter, a pH meter, and a concentration meter connected in sequence. The flow meter is used to measure the circulating flow rate, the pH meter is used to detect the pH value of the etching solution, and the concentration meter is used to detect the concentration of the etching solution. All three transmit the detection signals to the PLC main control unit. The PLC main control unit adjusts the speed of the circulating pump through an independent frequency converter.

[0023] The acoustic field includes a megohmmeter, megohmmeter transducers in each zone, an impedance analyzer, and a sound pressure level meter in each zone. The PLC main control unit is connected to the megasonic generator to set its output frequency, power and sweep range, thereby adjusting the megasonic frequency, power density and sweep range. The megasonic generator is connected to the transducer in each zone via multiple coaxial cables to drive the transducer to generate megasonic waves. The impedance analyzer is connected in parallel across the two ends of the transducer to measure the impedance characteristics of the transducer in operation and upload the measured impedance value to the PLC main control unit. Sound pressure meters arranged in each zone of the etching tank upload the sound pressure value of each zone to the PLC main control unit to obtain the sound pressure of the zone.

[0024] The thermal field includes temperature sensors (temperature sensor arrays) in each zone, heaters, cooling coils, heat exchangers, and constant temperature chillers in each zone. Among them, temperature sensors arranged in each zone upload temperature signals to the PLC main control unit to obtain the overall temperature of the etching solution and the temperature of each zone. The PLC main control unit controls the switching on and off of the heaters in each zone and the on / off state of the solenoid valves at the inlet of the cooling coils through the digital output port to achieve the required temperature control accuracy for each zone. The PLC main control unit communicates with the constant temperature chiller via Modbus to control its start / stop and outlet water temperature setting, so as to maintain the overall temperature stability of the etching solution.

[0025] The multi-dimensional sensing acquisition module is used for acquiring status data throughout the etching process.

[0026] Compared with the prior art, the advantages of the present invention are: 1. This invention replaces the traditional single-field and two-field independent adjustment modes by establishing a three-field parameter linkage and coordination control model; through the coordinated logic of chemical field to determine global rate, acoustic field to uniform mass transfer, and thermal field to correct local deviation, the PV degradation of the 5μm wavefront of large-size workpieces can be controlled within ≤30nm.

[0027] 2. This invention, through three-field coordinated adjustment, can reduce the concentration fluctuation and high temperature fluctuation of the etching solution while ensuring etching uniformity. At the same time, it avoids workpiece surface damage caused by long-term mega-acoustic high-power operation. While improving etching accuracy, it can control the workpiece surface roughness Rq degradation (the difference in root mean square roughness of the surface before and after etching) to ≤0.2nm and the single-piece etching time to ≤8h. Attached Figure Description

[0028] Figure 1 A flowchart of an adaptive control method for etching uniformity coupled with chemical, acoustic, and thermal fields; Figure 2 Diagram showing the connection relationships of the physical components involved in the adaptive control method for etching uniformity based on the coupling of three fields: acoustics, heat, and sound. Detailed Implementation

[0029] The adaptive control method for etching uniformity based on chemical-acoustic-thermal three-field coupling of the present invention will be described in more detail below with reference to schematic diagrams, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0030] Example 1 This embodiment takes the high-precision wet etching and shaping of an optical mirror as an example, with preset target etching parameters: Global etching rate tolerance Allowable deviation in local etching uniformity The target etching depth is 5 μm, the global average etching rate (target etching rate) is ≤80 nm / min, and the surface roughness Ra is ≤0.5 nm; the etching solution temperature is 25-35℃, and the megason power density is ≥6 W / cm². 2 .

[0031] like Figures 1-2 As shown, an adaptive control method for etching uniformity using chemical-acoustic-thermal three-field coupling includes:

[0032] (1) Establishment of the etching rate correlation model: An orthogonal experiment was designed, using chemical field parameters (3), acoustic field parameters (5), and thermal field parameters (2) as inputs, and the etching rate of each local area as the input. For output, use The orthogonal array was used to conduct 27 sets of experiments, and the etching rate of each local area was measured in each set of experiments. .

[0033] Multiple linear regression analysis (least squares method) was performed on the experimental data (all local etching rates) to calculate the estimated values ​​of each coefficient in the model (example values, units normalized): =5, =2.5, =0.8, =0.3, =1.2, =0.5, =0.1, =0.2, =0.05, =0.4, =0.6.

[0034] This yields the following linear regression model without interaction terms:

[0035] in, -Etching solution concentration; - pH value of the etching solution; - Circulation flow rate, i.e., the concentration of etching solution in the circulation pipeline; - Megatone frequency; - Megasonic power density; -Sweep frequency range; -No. Sound pressure level of the zones; -Transducer impedance; - Overall temperature of the etching solution; -No. Temperature of the zone; The model is stored in the program memory of the PLC main control unit in the form of a polynomial coefficient table. When the PLC runs, it directly calculates the local etching rate based on the parameters collected in real time. .

[0036] (2) Etching process parameter settings: Etching tank dimensions: 980mm×1000mm×250mm, the workpiece is divided into 4 independent temperature / sound control zones.

[0037] Chemical field: HF buffered etching solution, prepared at a volume ratio of 1:8 (HF:water), with a mass fraction of approximately 12% (in this embodiment, the concentration is...). 12%) Initial circulation flow The filter pump has a power of 0.55kW and a flow rate controlled at 1.8m / s.

[0038] The HF buffer etching solution is prepared at a ratio of 1:8, and the concentration of the etching solution in this ratio is approximately 12%.

[0039] Acoustic field: megaphon generator set frequency Power density Frequency sweep range Initial sound pressure levels for each zone (Measured) Transducer impedance .

[0040] Thermal field: Overall temperature The initial temperature of each zone is consistent with the overall temperature. (); zoned temperature control accuracy ±0.5℃; the cooling capacity of the constant temperature chiller is 1.8 times the rated power of the megacrylic transducer, so as to fully offset the heat generated by the etching reaction and the heat load generated by the operation of the megacrylic transducer.

[0041] Optimize and adjust the frequency matching parameters, power output parameters, and PID control gain parameters of the megohmmeter system (acoustic field) and drive control system (to achieve precise step size control through PID control).

[0042] 3) Real-time deviation calculation: During the etching process, multi-dimensional sensors collect data in real time and send it to the PLC main control unit. Assume that the parameters collected at a certain moment for each zone are slightly different (e.g., uneven temperature due to localized exothermic reactions), the specific values ​​are as follows: Table 1. Real-time data collected by multi-dimensional sensors

[0043] Substitute the above parameters into the model to calculate the real-time erosion rate of each partition. (Unit: nm / min):

[0044] Similarly, ; ; .

[0045] Global average etching rate:

[0046] Target global etching rate (target etching rate) (Default value); Global etching rate deviation: = nm / min; Local etching uniformity deviation (local uniformity deviation, i.e., local etching rate deviation): = ; = ; = ; = ; 4) Closed-loop regulation: Global etching rate tolerance: (i.e., etching rate error ≤ 120 nm / min) ）.

[0047] Allowable deviation for local etching uniformity: (This value is calculated based on the requirement that the PV degradation amount of a 5μm wavefront etching is ≤30nm, combined with the etching time. In this example, 1.0nm / min is used as an example.)

[0048] Comparison results: Global etching rate deviation The speed is much smaller than 120 nm / min, so the chemical field does not need to be adjusted.

[0049] In local uniformity deviation: The deviation in partition 4 is -1.4285 nm / min, which exceeds 1.0 nm / min in absolute value, requiring local correction. The deviations in the other partitions are all within the threshold and will not be adjusted for now.

[0050] The PLC main control unit only outputs adjustment parameters for partition 4: the temperature of this partition. Increase the temperature by 0.5°C and simultaneously increase the megaphonic power density of the zone by 10%. The adjustment command is sent to the actuator.

[0051] 5) Termination of etching: After several iterations of adjustment, the local etching rates tended to be consistent, and the global average etching rate approached 80 nm / min. When the cumulative etching depth (through the analysis of...) When the integral reaches 5μm, the PLC main control unit terminates the etching process and shuts down the megasonic system and etching solution circulation.

[0052] Measurements showed that the roughness Ra was 0.18 nm and the wavefront PV degradation after etching was 28 nm, which met the target requirements.

[0053] Example 2 This embodiment focuses on wet etching and shaping of semiconductor wafers.

[0054] Global etching rate tolerance Allowable deviation in local etching uniformity The target etching depth is 5 μm, the global average etching rate is ≤80 nm / min, and the surface roughness Ra is ≤0.5 nm.

[0055] The same control method was used, but the etching rate correlation model was obtained through COMSOL multiphysics simulation calibration.

[0056] The establishment of the etching rate correlation model in S1 specifically includes: Step 1: Establish a multiphysics simulation model: A two-dimensional axisymmetric model was built in COMSOL Multiphysics software to simulate the physical processes within the etching groove. The model includes the following modules: Chemical field: The "dilute mass transfer" interface is used to simulate the concentration distribution of reactants (such as TMAH) in the etching solution; the reaction kinetics adopt the Arrhenius equation, and the etching rate is related to temperature and concentration.

[0057] Acoustic field: The "pressure acoustics (frequency domain)" interface is used to simulate the sound pressure distribution generated by the mega-sound transducer; multiple zone sound sources are set at the bottom of the model, and the sound pressure amplitude of each zone can be set independently.

[0058] Thermal field: The "solid and fluid heat transfer" interface is adopted to take into account the heat exotherm of the etching reaction, the Joule heat generated by the megohmmeter transducer, and the convective heat transfer of the circulating etching solution.

[0059] Flow field: The "laminar flow" interface is used to simulate the circulating flow of the etching fluid in the tank, and the flow velocity boundary conditions are set according to the circulating flow rate Q.

[0060] Step 2: Set input parameters and level: Chemical field: concentration (1.5%~3.5%), pH value (10~13), Circulation flow rate (5~15L / min).

[0061] Acoustic field: mega-sound frequency (0.9~1.1MHz), power density (4~8W / cm) 2 ), frequency sweep range (1~5kHz), sound pressure levels in each zone (Determined by the zone power and tank size, ranging from 0.5 to 1.2 MPa), transducer impedance (45~60Ω, depending on frequency and load).

[0062] Thermal field: Overall temperature (35~45℃), temperature in each zone (The temperature may deviate by ±2℃ relative to the overall temperature).

[0063] Step 3: Perform simulation and obtain the etching rate of each partition.

[0064] Latin hypercube sampling was used to generate 200 sets of sample points in the input parameter space (ensuring uniform coverage). For each set of sample points, COMSOL simulation was run to calculate the etching rate of each partition (divided into 4 partitions) of the workpiece surface under steady-state conditions. (Obtained by dividing surface reaction flux by material density, unit: nm / min). Record each set of input parameters and its corresponding four... value.

[0065] Step 4: Obtain the model coefficients through regression analysis: 200 sets of simulation data (each set containing 10 input parameters and 4 outputs) Import the data into statistical analysis software. Use multiple linear regression (excluding cross terms) to... The dependent variable is 10 input parameters, which are independent variables. The model coefficients are obtained by fitting the model.

[0066] This leads to the linear regression model.

[0067] S2. Fix the semiconductor wafer in the etching tank, with the wafer facing the partitioned array of megaphonic transducers. Prepare TMAH etching solution; The chemical field circulation flow rate is 8 L / min, and the flow velocity is 1.6 m / s; The initial frequency of the acoustic field is 0.95MHz, and the power density is 5W / cm². 2 ; The initial temperature of the thermal field is 40℃, the temperature control accuracy is ±0.2℃, and the cooling capacity of the constant temperature subsystem is 1.5 times that of the megason power.

[0068] S3. By collecting data such as etching solution concentration, pH value, temperature, flow rate, mega-acoustic impedance, and sound field distribution at a sampling frequency of 1ms, the subsystem communicates through the OPC UA protocol, and the data is synchronously transmitted to the DCS system of the mass production line.

[0069] S4 and PLC adjust the parameters of the three fields in a coordinated manner based on the real-time collected deviation data. When the global etching rate deviates from the target value, adjust the etching solution concentration and circulation flow rate to correct the global etching rate; When etching deviations occur in local sub-regions, the temperature and mega-sound power of that region are adjusted accordingly to precisely correct the local etching rate. The megaphonic resonant frequency is tracked in real time during the etching process. PID control ensures stable power output, and the thermostatic subsystem counteracts the heat released by the reaction to maintain a stable etching solution temperature.

[0070] S5. Repeat steps S3-S4 to correct etching deviations in real time. When the global average etching depth of the workpiece reaches the target depth and the etching depth deviation of all sub-regions is controlled within 120nm, terminate the etching process and shut down the megohmmeter system and etching solution circulation.

[0071] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A chemical-acoustic-thermal three-field coupling adaptive control method for etching uniformity, characterized in that, Including the following steps: Step S1, Model Construction: Construct an etching rate correlation model with chemical field parameters, acoustic field parameters, and thermal field parameters as inputs and etching rate of each partition as output; Step S2, Parameter Preset and Etching Start: Based on the target etching requirements of the workpiece, set the target etching rate and target etching depth, and start the etching process; Step S3, Data Acquisition and Rate Output: The etching process uses multiple sensors belonging to chemical field, acoustic field and thermal field to collect state data in real time. The state data includes characteristic parameters of chemical field, acoustic field and thermal field. The collected feature parameters are input into the etching rate correlation model, and the current etching rate of each partition is output, which is recorded as the local etching rate. Step S4, Deviation Calculation and Closed-Loop Adjustment: Based on the local etching rates, the arithmetic mean of the local etching rates is taken to obtain the global etching rate; the global etching rate is compared with the target etching rate to obtain the global etching rate deviation. The local etching rate is compared with the global etching rate region by region to obtain the deviation of the local etching rate; Based on the sign and magnitude of the above deviations, the etching rate correlation model outputs the adjustment amounts of the chemical field, acoustic field, and thermal field; the PLC main control unit adjusts the characteristic parameters of the chemical field, acoustic field, and thermal field respectively according to the adjustment amounts. Step S5: Repeat steps S3 to S4 until the etching depth of the workpiece reaches the target etching depth, then terminate the etching process.

2. The adaptive control method for etching uniformity based on chemical-acoustic-thermal three-field coupling according to claim 1, characterized in that, The characteristic parameters of the chemical field include etching solution concentration, pH value, and circulation flow rate; the characteristic parameters of the acoustic field include megohmmeter frequency, power density, sweep frequency range, zone sound pressure, and transducer impedance; the characteristic parameters of the thermal field include overall etching solution temperature and zone temperature.

3. The adaptive control method for etching uniformity based on chemical-acoustic-thermal three-field coupling according to claim 2, characterized in that, The chemical field includes: The etching tank, circulation pump, filter pump, regulating valve, flow meter, pH meter and concentration meter are connected in sequence. The flow meter is used to measure the circulating flow rate, the pH meter is used to detect the pH value of the etching solution, and the concentration meter is used to detect the concentration of the etching solution. All three transmit the detection signals to the PLC main control unit.

4. The adaptive control method for etching uniformity based on chemical-acoustic-thermal three-field coupling according to claim 3, characterized in that, The PLC main control unit regulates the speed of the circulating pump through an independent frequency converter.

5. The adaptive control method for etching uniformity based on chemical-acoustic-thermal three-field coupling according to claim 2, characterized in that, The acoustic field includes: megohmmeter generator, megohmmeter transducers in each zone, impedance analyzer, and sound pressure level meter in each zone; The PLC main control unit is connected to the megasonic generator to set its output frequency, power and sweep range, thereby adjusting the megasonic frequency, power density and sweep range. The megasonic generator is connected to the transducer in each zone via multiple coaxial cables to drive the transducer to generate megasonic waves. The impedance analyzer is connected in parallel across the two ends of the transducer to measure the impedance characteristics of the transducer in operation and upload the measured impedance value to the PLC main control unit. Sound pressure meters arranged in each zone of the etching tank upload the sound pressure value of each zone to the PLC main control unit to obtain the sound pressure of the zone.

6. The adaptive control method for etching uniformity based on chemical-acoustic-thermal three-field coupling according to claim 2, characterized in that, The thermal field includes: temperature sensors in each zone, heaters in each zone, cooling coils, heat exchangers, and constant temperature chillers; Among them, temperature sensors arranged in each zone upload temperature signals to the PLC main control unit to obtain the overall temperature of the etching solution and the temperature of each zone. The PLC main control unit controls the switching on and off of the heaters in each zone and the on / off state of the solenoid valves at the inlet of the cooling coils through the digital output port to achieve the required temperature control accuracy for each zone. The PLC main control unit communicates with the constant temperature chiller via Modbus to control its start / stop and outlet water temperature setting, so as to maintain the overall temperature stability of the etching solution.

7. The adaptive control method for etching uniformity based on chemical-acoustic-thermal three-field coupling according to claim 1, characterized in that, The etching rate correlation model is a polynomial model based on orthogonal experimental data fitting, established from multiphysics simulation results. This model is stored in the PLC's program memory in the form of a lookup table or interpolation function.

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