Wafer Edge Release Device for Electrostatic Chuck

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Solution Overview

Problem

Existing wafer handling systems face challenges in safely releasing wafers from chucks, especially in low-pressure environments, where residual electrostatic charges can cause attractive forces, leading to damage and inaccuracy during processing.

Innovation Solution

A chuck system with an integral release device that mechanically contacts the wafer at its edge portion, allowing for controlled release and minimizing damage to the wafer's surface by avoiding the use of tripods or pins, which reduces the risk of scratches and parasitic plasma effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional tripods or pins are used to release the wafer from the chuck, then the wafer can be released from the chuck, but the wafer surface may be damaged by scratches and parasitic plasma effects

Engineering Contradiction:

Improvewafer surface integrityVSAvoidsurface damage and parasitic plasma effects

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the harmful elements (tripods and pins) from the wafer release mechanism and replaces them with a edge-contacting release device. The release device contacts only the edge portion of the wafer, extracting the source of surface damage while maintaining the release function.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The release device acts as an intermediary between the chuck and the wafer surface. Instead of direct contact between pins/tripods and the wafer surface, the release device mechanically contacts only the edge portion, mediating the release process without transmitting harmful forces to the productive surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If mechanical contact is made at the edge portion of the wafer, then surface damage is minimized, but the release mechanism becomes more complex

Engineering Contradiction:

Improvewafer surface integrityVSAvoidrelease device structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The release device is segmented into multiple independent elements (first release device element and second release device element) that can contact different portions of the wafer edge. This segmentation allows for simplified individual components while achieving the overall function through coordinated action of multiple elements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from point-contact release (pins touching the surface) to edge-contact release. By moving the contact zone to the edge dimension, the release mechanism avoids surface penetration while maintaining mechanical control through the edge portion of the wafer.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Force

If residual electrostatic charges are present in low-pressure environments, then the wafer remains held to the chuck, but attractive forces cause damage and inaccuracy during processing

Engineering Contradiction:

Improveelectrostatic attractive forceVSAvoidprocessing accuracy

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The release device is actuated before the wafer is transferred from the chuck to prevent residual electrostatic charges from causing damage during subsequent handling. By performing the release action preliminarily, the system eliminates the harmful attractive forces before they can affect processing accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The release mechanism applies a preliminary counter-force to the electrostatic attractive force by mechanically lifting the wafer edge. This preliminary anti-action neutralizes the electrostatic hold before the wafer enters the processing environment where accuracy is critical.

Inventive Principle:

Principle #9Preliminary anti-action

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

The solution ensures precise and damage-free wafer release, maintaining the integrity of the wafer's surface and preventing unwanted processing, thereby enhancing processing accuracy and reducing operational costs associated with protective layers.

Implementation Method 1

The processing chamber is configured to adjust an ambient pressure inside the processing chamber, wherein the ambient pressure is smaller than an atmospheric pressure

Methodology Applied

Scientific EffectPressure adjustment:

Implementation Method 2

Existing wafer handling systems face challenges in safely releasing wafers from chucks, especially in low-pressure environments, where residual electrostatic charges can cause attractive forces

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Data Source

PatentUS10186445B2Wafer releasing

Publication Date: 2019.01.22 INFINEON TECHNOLOGIES AG

AI summary

Embodiments of the present invention provide a chuck system for handling a wafer that comprises a first and a second main surface. The chuck system includes a chuck configured to hold the wafer at the second main surface facing the chuck and a release device. The chuck system further includes an actuator configured to lift the release device away from the chuck. The release device is configured such that the release device mechanically engages with the wafer at an edge portion of the second main surface of the wafer when being lifted, thereby releasing the wafer from the chuck.