Electrostatic Chuck Clamping Verification via Displacement Gauge

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Solution Overview

Problem

Conventional methods for ascertaining substrate clamping on electrostatic chucks are ineffective for high resistance and insulating substrates, as the small change in capacitance makes it difficult to determine if the substrate is properly clamped.

Innovation Solution

Incorporating a displacement gauge to measure the distance changes between the substrate and the electrostatic chuck before and after voltage application, allowing for the determination of proper clamping through distance differences, independent of the substrate's electrical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If capacitance measurement method is used to ascertain substrate clamping, then clamping status can be determined for conductive substrates, but the method becomes ineffective for high resistance and insulating substrates due to very small capacitance change values

Engineering Contradiction:

Improvecapacitance change detectionVSAvoidclamping ascertainment reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the electrical measurement system (capacitance measurement) with a mechanical measurement system (displacement gauge) to detect substrate clamping status. The displacement gauge measures physical distance changes between the substrate and electrostatic chuck surface, providing reliable detection for both conductive and insulating substrates without being limited by substrate electrical properties.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a displacement gauge as an intermediary measurement device between the substrate and the measurement system. This intermediary device enables indirect measurement of clamping force through distance measurement, allowing reliable detection of substrate contact and clamping status without direct electrical contact with the substrate.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If capacitance measurement is used for insulating substrates, then measurement can be performed, but the very small capacitance change (several pF) makes it difficult to accurately determine normal clamping

Engineering Contradiction:

Improvesubstrate type compatibilityVSAvoidcapacitance change measurement precision

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent replaces the electrical capacitance measurement system with a mechanical displacement measurement system. The displacement gauge directly measures the physical distance between the substrate and electrostatic chuck, providing sufficient measurement precision (capable of detecting sub-micrometer changes) regardless of substrate electrical properties or capacitance change magnitude.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from electrical capacitance (which shows very small changes of several pF for insulating substrates) to mechanical displacement (which shows larger, more easily detectable changes in distance). This parameter transformation enables reliable measurement across all substrate types including high resistance and insulating substrates.

Inventive Principle:

Principle #35Parameter changes

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 reliable and accurate assessment of substrate clamping without relying on electrical properties, preventing substrate damage during transportation and processing.

Implementation Method 1

an electrostatic chuck that has an electrode therein and is provided with a substrate holding surface, on one side of which a substrate is held

Methodology Applied

Scientific EffectElectrostatic clamping: Electrostatics

Data Source

PatentUS9601359B2Substrate holding device, semiconductor fabrication device, and substrate clamping ascertainment method

Publication Date: 2017.03.21 NISSIN ION EQUIPMENT CO LTD

AI summary

A substrate holding device is provided with an electrostatic chuck that has an electrode therein and is provided with a substrate holding surface, on one side of which a substrate is held; a displacement gauge that is disposed above or below the substrate holding surface; and a controller which, along with using the displacement gauge to measure a first distance to the substrate when a substrate is placed on the substrate holding surface, uses the displacement gauge to measure a second distance to the substrate after a predetermined voltage is applied to the electrode of the electrostatic chuck and, based on the difference between the measured distances, ascertains whether the clamping of the substrate to the electrostatic chuck has been performed in a normal manner.