Guard Ring Plasma Chamber Radial Gap Stability

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Solution Overview

Problem

Existing plasma processing chambers face challenges in maintaining consistent plasma confinement and minimizing contamination during semiconductor wafer etching, particularly due to variations in radial gaps and exposure to free radicals and ions, which affect etching precision and chamber performance.

Innovation Solution

Incorporation of a guard ring surrounding the backing member and plasma confinement assembly, which maintains a consistent radial gap and minimizes exposure to plasma, using materials with low thermal expansion and electrical insulation properties to stabilize the system over a broad temperature range, and preventing contact between components to enhance gas flow and reduce contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the radial gap between the backing member and confinement assembly is reduced to improve plasma confinement, then plasma confinement is improved, but thermal expansion variations cause gap instability and contact between components

Engineering Contradiction:

Improveplasma confinement consistencyVSAvoidradial gap stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

A guard ring is introduced as an intermediary component between the backing member and the confinement assembly. This guard ring acts as a mediator that maintains the radial gap stability while allowing for thermal expansion variations, preventing direct contact between the backing member and confinement assembly, thus ensuring consistent plasma confinement without compromising gap stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the backing member is exposed to plasma to simplify structure, then structural simplicity is improved, but contamination increases due to free radical and ion exposure

Engineering Contradiction:

Improveassembly structure simplicityVSAvoidplasma contamination

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The guard ring serves as a protective intermediary that shields the backing member from direct plasma exposure. By positioning the guard ring between the plasma environment and the backing member, it reduces contamination from free radicals and ions while maintaining the relative structural simplicity of the assembly.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stability of the object's composition

If thermal expansion compensation is implemented to maintain gap stability, then gap stability is improved, but device complexity increases

Engineering Contradiction:

Improveradial gap stabilityVSAvoidthermal compensation mechanism

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The system utilizes parameter changes in the form of thermal expansion characteristics of different materials. The guard ring is made from a material with a coefficient of thermal expansion intermediate between the backing member and confinement assembly, allowing it to naturally compensate for thermal expansion variations and maintain radial gap stability through material property selection rather than complex mechanical compensation mechanisms.

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

The solution ensures consistent plasma confinement and reduced contamination, improving etching precision and chamber performance by maintaining stable radial gaps and protecting components from plasma exposure, thus enhancing the reliability and efficiency of semiconductor wafer processing.

Implementation Method 1

using materials with low thermal expansion and electrical insulation properties to stabilize the system over a broad temperature range

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

using materials with low thermal expansion and electrical insulation properties to stabilize the system over a broad temperature range

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Implementation Method 3

a plasma confinement assembly, which surrounds an outer periphery of the upper electrode and the backing member

Methodology Applied

Scientific EffectPlasma confinement: Magnetic Field

Data Source

PatentUS7939778B2Plasma processing chamber with guard ring for upper electrode assembly

Publication Date: 2011.05.10 LAM RES CORP

AI summary

A plasma processing chamber, which includes an upper electrode assembly, a lower electrode assembly, and a plasma confinement assembly. The upper electrode assembly includes an upper electrode, a backing member, the backing member attachable to an upper surface of the upper electrode, and a guard ring surrounding an outer surface of the backing member and located above the upper surface of the upper electrode, wherein the guard ring is configured to provide an inner gap between the outer surface of the backing member and an inner periphery of the guard ring. The lower electrode assembly is adapted to receive a semiconductor substrate. The plasma confinement assembly is separated from an outer periphery of the upper electrode and the backing member by the guard ring.