Consumable Isolation Ring for Plasma Chamber RF Confinement

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In plasma processing chambers, the flow of RF current outside the confined chamber volume can lead to the formation of unconfined plasma due to RF fields in the external region, causing inefficiencies and potential etch stop or plasma extinguishment issues.

Innovation Solution

A consumable isolation ring with an adjustable gap and recesses is introduced to provide a short RF return path, preventing the ignition of unconfined plasma by enhancing the confinement of RF currents within the processing chamber.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If RF current flows outside the confined chamber volume, then the processing chamber can operate, but unconfined plasma forms causing inefficiencies and potential etch stop or plasma extinguishment

Engineering Contradiction:

Improveplasma stabilityVSAvoidunconfined plasma formation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The isolation ring acts as an intermediary component between the substrate support assembly and the chamber wall. It provides a dedicated RF current return path through its conductive structure, preventing RF current from flowing through the chamber wall and external regions. The ring electrically connects the substrate support to the chamber ground while physically confining the current flow within the chamber volume, thus eliminating unconfined plasma formation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The isolation ring introduces localized electrical conductivity at the periphery of the substrate support assembly. By placing conductive material (the ring) in this specific location, the patent creates a preferred RF current return path locally, rather than allowing current to distribute throughout the entire chamber structure. This localized conductivity modification ensures RF current returns through a controlled path, preventing harmful external plasma while maintaining overall system operation.

Inventive Principle:

Principle #3Local quality

2Reliability

If the chamber pressure is maintained below 200 mTorr, then plasma can be sustained, but plasma extinguishment can occur if pressure is too low

Engineering Contradiction:

Improveplasma sustainmentVSAvoidpressure range tolerance

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The isolation ring provides a stable electrical reference and controlled RF current return path that creates a more predictable plasma environment. This stability acts as a form of passive feedback, maintaining consistent electrical conditions that help the plasma remain sustained across a broader pressure range. The ring ensures that RF power coupling remains effective even as pressure varies, preventing premature plasma extinguishment.

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

The solution effectively confines RF currents, reducing the formation of unconfined plasma and maintaining stable plasma conditions within the chamber, thereby improving processing accuracy and repeatability.

Implementation Method 1

Methodology Applied

Scientific EffectRF current confinement: Electromagnetic Induction

Data Source

PatentUS9171702B2Consumable isolation ring for movable substrate support assembly of a plasma processing chamber

Publication Date: 2015.10.27 LAM RES CORP

AI summary

A consumable isolation ring of a movable substrate support assembly is described. The consumable isolation ring is configured to be supported on a step of a movable ground ring fit around a fixed ground ring. The consumable isolation ring is configured to electrically isolate the movable ground ring from a dielectric ring of the movable substrate support assembly.