Electrostatic Chuck Dechucking Plasma Neutralization

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Solution Overview

Problem

Residual sticking forces between wafers and electrostatic chucks during dechucking operations in plasma processing chambers, caused by charge trapping and surface film buildup, lead to issues like wafer popping and breakage due to differences in thermal expansion and increased contact area.

Innovation Solution

An electrostatic chuck design with a cavity for forming a dechucking plasma that neutralizes charges on the wafer and chuck surface by applying a dechucking plasma after shutting off the electrostatic clamping voltage, using a heat transfer gas at controlled pressures to reduce residual sticking forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If electrostatic clamping voltage is applied to hold the wafer on the chuck, then wafer clamping force is improved, but residual sticking force remains after voltage shutdown causing wafer popping and breakage

Engineering Contradiction:

Improvewafer clamping forceVSAvoiddechucking reliability

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The patent converts the harmful residual sticking force caused by charge trapping into a beneficial effect by using plasma to neutralize these charges. The plasma, generated by introducing a noble gas and applying RF power, eliminates the trapped charges that cause wafer popping and breakage during dechucking, thereby transforming the problem into a solution.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces plasma as an intermediary substance between the wafer and the electrostatic chuck during the dechucking process. This plasma layer acts as a mediator that neutralizes the electrostatic charges on both the wafer backside and the chuck surface, allowing the wafer to be released without residual sticking forces.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If heat transfer gas is supplied at high pressure to reduce contact area, then wafer damage is prevented, but dechucking control becomes difficult

Engineering Contradiction:

Improvewafer damageVSAvoiddechucking control

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent changes the pressure parameter of the heat transfer gas dynamically during the dechucking process. By reducing the gas pressure from the high pressure used during processing to a lower pressure during dechucking, the plasma can effectively neutralize charges while maintaining adequate separation between the wafer and chuck, preventing wafer damage without compromising control.

Inventive Principle:

Principle #35Parameter changes

3Force

If electrostatic chuck surface is made smoother to increase contact area, then clamping force is improved, but residual charge effects are enhanced causing more sticking

Engineering Contradiction:

Improveclamping forceVSAvoidresidual sticking force

Core Design Contradiction:

ForceVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful effect of enhanced charge trapping on smooth surfaces into a benefit by using plasma neutralization. The plasma effectively removes the trapped charges that accumulate on the smooth electrostatic chuck surface, transforming the problematic charge retention into a controlled state that prevents residual sticking forces.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 method effectively reduces residual sticking forces, ensuring robust dechucking by neutralizing charges and minimizing contact area, thereby preventing wafer damage and improving dechucking reliability.

Implementation Method 1

at least one electrostatic clamping electrode which applies an electrostatic clamping force to the wafer on the support surface when an electrostatic clamping voltage is applied to the clamping electrode

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Implementation Method 2

forming a dechucking plasma in a cavity in the electrostatic chuck and neutralizing charges on the underside of the wafer and support surface of the electrostatic chuck with the dechucking plasma

Methodology Applied

Scientific EffectPlasma: Plasma

Data Source

PatentUS8520360B2Electrostatic chuck with wafer backside plasma assisted dechuck

Publication Date: 2013.08.27 LAM RES CORP

AI summary

An electrostatic chuck assembly useful in a plasma processing chamber, comprising a support surface on which a semiconductor wafer is supported during processing of the wafer in the chamber, at least one electrostatic clamping electrode which applies an electrostatic clamping force to the wafer on the support surface when an electrostatic clamping voltage is applied to the clamping electrode, at least one outlet in the support surface which delivers a heat transfer gas to an underside of the wafer, at least one gas passage connected to a source of heat transfer gas operable to supply heat transfer gas at a desired pressure to the at least one gas passage, and at least one cavity and plasma generating electrode along the at least one gas passage, the plasma generating electrode operable to form a dechucking plasma in the cavity, the dechucking plasma being effective to neutralize charges on the underside of the wafer and support surface of the electrostatic chuck and thereby reduce a residual sticking force between the wafer and the support surface.