Electrostatic Chuck Impedance Sensing for Chucking Voltage Control

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Solution Overview

Problem

Existing electrostatic chucks in substrate processing systems face challenges with over-chucking, under-chucking, and incomplete de-chucking, leading to substrate damage, arcing, and inconsistent processing due to inadequate detection and control of chucking status.

Innovation Solution

A method for monitoring and controlling electrostatic chucking status by supplying chucking voltage, measuring impedance at a frequency range, normalizing the impedance, and comparing it to baseline values to determine the chucking status, and adjusting the voltage accordingly to ensure optimal chucking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If electrostatic chucking is used to hold substrates, then substrate damage from mechanical clamps is reduced, but over-chucking and under-chucking can still cause substrate damage and arcing

Engineering Contradiction:

Improvesubstrate damage from mechanical clampsVSAvoidsubstrate damage from over/under-chucking

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent implements a feedback mechanism by measuring the impedance of the electrostatic chuck and comparing it to reference values to determine chucking status. This closed-loop feedback system enables real-time monitoring and adjustment of chucking voltage to prevent over-chucking and under-chucking, thereby resolving the reliability issue while maintaining the benefit of mechanical-free substrate holding.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces mechanical detection methods with electrical impedance measurement to monitor chucking status. By substituting mechanical sensing with electrical field-based impedance measurement, the system achieves non-contact, real-time detection of substrate chucking state, preventing damage while eliminating mechanical wear and contamination issues.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If impedance measurement is used to detect chucking status, then real-time monitoring capability is improved, but measurement precision is affected by frequency dependence

Engineering Contradiction:

Improvereal-time monitoring capabilityVSAvoidimpedance measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent addresses frequency dependence by measuring impedance across multiple frequencies and identifying the frequency at which impedance reaches its maximum value. This parameter-based approach (using frequency as a variable) enables accurate determination of chucking status despite frequency effects, as the peak impedance frequency corresponds to the resonant frequency of the substrate-chuck system.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent transitions from single-frequency impedance measurement to multi-frequency spectral analysis. By adding the frequency dimension to the measurement, the system can distinguish between different chucking states more accurately, as each state produces a characteristic impedance-frequency signature that can be identified through spectral analysis.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Device complexity

If fixed chucking voltage is applied to electrostatic chuck, then system complexity is reduced, but incomplete de-chucking can cause substrate breakage

Engineering Contradiction:

Improvevoltage control system simplicityVSAvoidsubstrate breakage from incomplete de-chucking

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements feedback control by continuously monitoring impedance and using this information to dynamically adjust chucking voltage. During de-chucking, the system detects impedance changes that indicate incomplete release and automatically adjusts voltage to ensure complete substrate release, preventing breakage while maintaining simple overall system architecture through intelligent control algorithms.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables real-time detection and control of substrate chucking status, preventing substrate damage and ensuring consistent processing by maintaining optimal chucking conditions, thereby improving processing reliability and substrate integrity.

Implementation Method 1

Electrostatic chucks (ESCs) utilize electrostatic attraction to secure the substrate without a mechanical clamp

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Implementation Method 2

measuring an impedance of the signal, comparing the measured impedance to a baseline impedance value to obtain a chucking status value

Methodology Applied

Scientific EffectElectrical impedance: Electrical Resistance

Data Source

PatentUS20260081119A1Chucking status detection with chucking sensor normalized figure of merit and active chucking voltage control

Publication Date: 2026.03.19 APPLIED MATERIALS INC

AI summary

A method for monitoring a chucking status of a substrate, including: supplying chucking voltage to an electrostatic chuck disposed in a substrate pedestal, wherein a substrate is supported by the substrate pedestal, sending a signal to an electrode of an electrostatic chuck at a frequency range, measuring an impedance of the signal, comparing the measured impedance to a baseline impedance value to obtain a chucking status value, and determining a chucking status of the substrate based on the chucking status value, wherein the chucking status comprises not-chucked, under-chucked, fully-chucked, or over-chucked.