CN-122018389-A - Electrostatic chuck controller, control method and electrostatic chuck

CN122018389ACN 122018389 ACN122018389 ACN 122018389ACN-122018389-A

Abstract

The invention discloses an electrostatic chuck controller, a control method and an electrostatic chuck, which comprises an adsorption voltage output module, a multi-band impedance spectrum module and an adaptive control unit, wherein the adsorption voltage output module comprises an adsorption voltage output module and a wafer bias module, the adsorption voltage output module is a floating and reconfigurable high-voltage power supply group, a power supply reference ground GND_HP of the adsorption voltage output module is connected with a high-voltage output end V_bias of the wafer bias module, so that voltages V_A and V_B generated by the adsorption voltage output module float by taking the V_bias as references, the reconfigurable adsorption waveform module is composed of a high-voltage amplifier array controlled by an FPGA and can synthesize complex waveforms, the multi-band impedance spectrum module applies sine sweep signals from low frequency to high frequency to electrodes, calculates complex impedance by measuring the amplitude and phase difference of the voltage and the current on each frequency point, and the adaptive control unit outputs a material type identifier M_id and a resistivity estimated value of a current wafer.

Inventors

SHI XINYAO
ZHANG XIAOFENG
DING ZHENGYONG
Xu Zichuo
ZHAO YAN

Assignees

苏州矽视科技有限公司

Dates

Publication Date: 20260512
Application Date: 20251230

Claims (7)

1. An electrostatic chuck controller, comprising: The adsorption voltage output module comprises an adsorption voltage output module and a wafer bias module, wherein the adsorption voltage output module is electrically connected with the wafer bias module, voltages V_A and V_B generated by the adsorption voltage output module float by taking V_bias as references, and the wafer bias module is connected to the sucker body; The reconfigurable adsorption waveform module is composed of a high-voltage amplifier array controlled by an FPGA (field programmable gate array), and synthesizes complex waveforms, including unipolar direct current, bipolar direct current, alternating current superimposed direct current and pulse waveforms; the multi-band impedance spectrum module is used for applying sine sweep signals from low frequency to high frequency to the electrodes, calculating complex impedance by measuring the amplitude and phase difference of voltage and current on each frequency point, and deducing equivalent parallel capacitance and equivalent parallel resistance; The self-adaptive control unit is used for storing a structured and extensible database and a trained support vector machine classifier model, wherein the support vector machine classifier model is used for matching a real-time feature vector with a material fingerprint in the database and outputting a material type identifier M_id and a resistivity estimated value of a current wafer; The electrostatic chuck body is internally provided with at least two insulated adsorption electrodes which are respectively connected to voltages V_A and V_B generated by the adsorption voltage output module and a measuring channel of the multi-band impedance spectrum module through high-voltage cables, and the electrostatic chuck body also comprises a grounding pin for providing a release loop for induced charges under an unbiased working condition.
2. An electrostatic chuck controller control method employing the method of claim 1, comprising the steps of: step 1, after a wafer is transmitted to a sucker position, detecting the existence of the wafer through a suction voltage output module by a self-adaptive control unit, extracting a feature vector, matching the feature vector F with a database through a support vector machine classifier model, and outputting a material type identifier M_id and a resistivity estimated value rho_est; Step 2, self-adaptive adsorption and state confirmation, Step 2.1, the self-adaptive control unit calls an initial parameter set P_0:P_0= { adsorption waveform type, a voltage amplitude V_set, a sweep frequency judgment weight vector W and a capacitance threshold C_th } from a database according to M_id; For low resistance material (m_id=1) p_0= { waveform: bipolar dc, v_set ± 400V, W: [0.1, 0.1..0.8 ] (high frequency point weight, c_th: 1.5}; For high-resistance material (m_id=2) p_0= { waveform: unipolar dc, v_set: +600v/0V, W: [0.7, 0.2,..0.1 ] (low frequency point weight heavy), c_th: 1.1}; a variable gain rule of k_i=ki0/(1+γ×ρ_est), where k_i0 is a nominal integral gain and γ is an attenuation coefficient for reducing the integral speed; Step 2.2, the self-adaptive control unit controls the adsorption voltage output module to output a target waveform through a variable gain PID algorithm, and the gain K_i of the integral term I_term of the self-adaptive control unit can be dynamically adjusted according to ρ_est to avoid integral saturation; Step 2.3, in the adsorption process, the multi-band impedance spectrum module continuously monitors C_th on a key frequency point, and the self-adaptive control unit calculates a comprehensive adsorption index; step 3, in the adsorption maintaining stable stage, the self-adaptive control unit continuously monitors leakage current I_leak, predicts residual charge based on a dynamic charge trap model, and starts online micro-neutralization when the residual charge exceeds a safety threshold; step4, entering a four-stage intelligent release sequence after receiving a release instruction: The self-adaptive control unit controls the adsorption voltage output module to reduce the values of V_A and V_B to 0V, and simultaneously, applies a small-amplitude pulse train which is negative relative to V_bias to neutralize, and optimizes the width T_w and interval T_d of the pulse according to the final value of Q_res and M_id; Step 2, applying an alternating voltage with the frequency being scanned from low frequency to high frequency and the amplitude being gradually attenuated from rated voltage to zero so as to promote the recombination and release of the alternating voltage; Step 3, in each step gap, the multi-band impedance spectrum module rapidly measures C_p (f_low), the self-adaptive control unit calculates dC/dt, and if dC/dt does not approach zero, the waveform parameters of the next step are dynamically adjusted to form a closed-loop release control; Stage 4, after confirming that the wafer has been released, V_bias drops to zero with a controlled slope.
3. The method of claim 2, wherein step 1 performs a fast sweep without applying a high suction voltage, extracts eigenvectors F, F= [ C_p (F1), C_p (F2) ], C_p (F10), R_p (f_low), R_p (f_high), Wherein, the sensitivity to dielectric polarization f_low, the sensitivity to conductor f_high, the equivalent parallel capacitance C_p (omega), and the equivalent parallel resistance R_p (omega).
4. The method according to claim 2, wherein the step 3 predicts residual charge Q_res based on a dynamic charge trap model, Q_res (k) =α.Q_res (k-1) +β.I_leak (k). DELTA.t, wherein the charge decay factor α characterizes a natural leakage rate of the charge; When |q_res (k) | exceeds the safety threshold q_safe, online micro-neutralization is initiated.
5. The method of claim 2, wherein the integrated adsorption index S_index S_index=W.ΔC_p/C_p0 in step 2.3, wherein ΔC_p is a difference vector between the current capacitance and the reference capacitance C_p0 without wafer, and represents a dot product.
6. A computer medium having a program stored thereon, characterized in that the program, when being executed by a processor, realizes the steps of the method according to any of the claims 2-5.
7. An electrostatic chuck comprising an electrostatic chuck body on which the controller of claim 1 is mounted, wherein the electrostatic chuck controller comprises: the adsorption voltage output module comprises an adsorption voltage output module and a wafer bias module, wherein the adsorption voltage output module is electrically connected with the wafer bias module, so that voltages V_A and V_B generated by the adsorption voltage output module float by taking V_bias as a reference, and the wafer bias module is electrically connected to the sucker body; The reconfigurable adsorption waveform module is composed of a high-voltage amplifier array controlled by an FPGA, and can synthesize complex waveforms, including unipolar direct current, bipolar direct current, alternating current superposition direct current and pulse waveforms; the multi-band impedance spectrum module is used for applying sine sweep signals from low frequency to high frequency to the electrodes, calculating complex impedance by measuring the amplitude and phase difference of voltage and current on each frequency point, and deducing equivalent parallel capacitance and equivalent parallel resistance; The self-adaptive control unit is used for storing a structured and extensible database and a trained support vector machine classifier model, wherein the support vector machine classifier model is used for matching a real-time feature vector with a material fingerprint in the database and outputting a material type identifier M_id and a resistivity estimated value of a current wafer; The electrostatic chuck body is internally provided with at least two insulated adsorption electrodes which are respectively connected to voltages V_A and V_B generated by the adsorption voltage output module and a measuring channel of the multi-band impedance spectrum module through high-voltage cables, and the electrostatic chuck body also comprises a grounding pin for providing a release loop for induced charges under an unbiased working condition.

Description

Electrostatic chuck controller, control method and electrostatic chuck Technical Field The invention belongs to the technical field of electrostatic chucks, and particularly relates to an electrostatic chuck controller, a control method and an electrostatic chuck. Background Electrostatic chucks are key components used for fixing wafers or workpieces in semiconductor manufacturing, precision electronics, and other industries, and achieve non-contact fixing by electrostatic attraction. The electrostatic chuck mainly depends on two electrostatic adsorption forces to work: The coulomb force type electrostatic chuck applies a direct current high voltage through the electrode, and the wafer is absorbed by utilizing the coulomb force between opposite charges, so that the absorption force is strong and stable. However, the wafer is difficult to be removed due to residual charges after power failure, and the charges are needed to be neutralized by reverse voltage or alternating current for 'suck-back'. Johnsen-Rahbek electrostatic chucks rely on a dielectric layer with a specific conductivity, and charge is trapped in the medium to create an attractive force. The adsorption force is smaller, but the charge naturally leaks after power failure, and complex desorption is not needed. The manufacturing process is complex, the cost is high, and the control difficulty of the yield is high. Thus, the coulomb force type electrostatic chuck occupies a larger area in the semiconductor device in consideration of both yield and process cost. A complete electrostatic chuck includes an electrostatic chuck controller in addition to the chuck body. The electrostatic chuck controller is a precision electronic device integrating a high voltage power supply, control logic, monitoring and protection circuitry. Its core task is to provide stable, controllable high voltage dc power to the electrostatic chuck as needed and manage the entire "suck-hold-release" workflow. The performance of the electrostatic chuck directly determines whether the electrostatic chuck can reliably and safely work, thereby influencing the normal operation of the whole semiconductor process equipment and the yield of the final wafer. A high quality electrostatic chuck must be equipped with a high performance controller to perform its full function. The existing electrostatic chuck controller contains the following key modules and functions: 1. And the high-voltage direct current power supply is used for generating high-voltage direct current required by the electrostatic chuck, and the output voltage is usually adjustable. 2. And the accurate voltage and current monitoring is to monitor the output voltage and current in real time so as to ensure stable adsorption force. 3. And detecting the adsorption state, namely judging whether the wafer is adsorbed correctly or not by monitoring parameters such as current and the like. 4. And (3) programmable time sequence control, namely controlling the whole adsorption and release process. 5. Safety interlock and protection, ensuring the safety and reliability of the system and preventing the damage to equipment or wafers. 6. And the communication interface is used for communicating with an upper computer or an equipment main control system. The existing electrostatic chuck controller can only output two fixed high voltages, and is provided with overcurrent protection, which may face the following dilemma in practical use, especially in some complex scenes such as electron beam quantity detection equipment. The electrostatic chuck controller provides only "pull" and "put" instructions, which can lead to wafer sticking problems caused by long-term polarization. After the adsorption process is finished and the power supply is turned off, the wafer or the workpiece is still firmly adsorbed on the sucker and cannot be taken down smoothly. Particularly under ultra-high vacuum, the polarized charges on the surface of the electrostatic chuck are difficult to release. Meanwhile, in some complex scenarios such as electron beam detection equipment, the electron beam continuously charges the wafer surface, further exacerbating the residual charge, and causing wafer adhesion to be more serious. If the charge is not released effectively, during the wafer transfer process, when the wafer is lifted up, the charge amount Q is unchanged, the distance d is increased, the capacitance C is reduced, resulting in voltage rise, the wafer will generate a reverse voltage to the electrostatic chuck surface, which easily causes chuck surface breakdown and wafer damage. The controller outputs voltage to the electrode of the electrostatic chuck to realize electrostatic induction. If a bias voltage needs to be applied to the wafer, the output of the controller can only be disconnected, and the wafer is attracted by utilizing residual electrostatic attraction. In the process of applying bias to a wafer, two phase electrodes of the electrostatic chuck ar