Exclusion Ring Flow Paths for Wafer Edge Gas Exhaust

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Solution Overview

Problem

In semiconductor fabrication, bowed wafers can cause the exclusion ring to vibrate due to contact with the wafer edge, leading to unwanted bevel and backside deposition, as well as particulate generation, due to trapped wafer edge gas accumulating and building pressure.

Innovation Solution

An exclusion ring with a plurality of flow paths, such as slots or channels, is designed to allow wafer edge gas to escape outward, preventing pressure buildup and vibration by directing a portion of the gas towards the chamber walls while ensuring sufficient gas remains to prevent unwanted deposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the exclusion ring is used to prevent edge deposition, then deposition control is improved, but wafer edge gas accumulates and causes ring vibration

Engineering Contradiction:

Improvedeposition controlVSAvoidexclusion ring stability

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The exclusion ring is segmented with multiple flow paths (slots or channels) distributed around its perimeter, dividing the gas exhaust function into multiple discrete locations. This segmentation allows gas to escape at multiple points rather than accumulating in a single trapped region, preventing pressure buildup and ring vibration while maintaining the exclusion ring's primary function of preventing edge deposition.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The flow paths act as intermediary channels that mediate between the trapped wafer edge gas and the chamber environment. These pathways provide a controlled interface for gas escape, allowing the exclusion ring to maintain its structural integrity and position while enabling pressure relief through the intermediate flow path structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If the exclusion ring prevents gas escape, then deposition on bevel and backside is avoided, but pressure buildup causes vibration and particulate generation

Engineering Contradiction:

Improveunwanted depositionVSAvoidring vibration and particulates

Core Design Contradiction:

Object-generated harmful factorsVSObject-affected harmful factors

Solution Approach 1:

The harmful trapped gas is extracted from the system through the flow paths, removing the source of pressure buildup before it can cause vibration and particulate generation. The flow paths provide dedicated extraction channels that remove the harmful gas accumulation while the exclusion ring's solid structure continues to prevent unwanted deposition on the wafer bevel and backside.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The trapped wafer edge gas, which initially causes harmful vibration and particulate generation, is converted into a beneficial controlled flow through the flow paths. By providing structured pathways for gas escape, the previously harmful pressure buildup is transformed into a controlled exhaust process that prevents vibration while the exclusion ring continues to protect against unwanted deposition.

Inventive Principle:

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

3Ease of manufacture

If the exclusion ring structure is simplified, then manufacturing is easier, but gas flow control and vibration prevention are reduced

Engineering Contradiction:

Improveexclusion ring fabricationVSAvoidvibration prevention

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The exclusion ring incorporates localized flow path features (slots or channels) at specific locations around the ring perimeter, rather than requiring a complete redesign of the entire ring structure. This local quality approach allows the majority of the exclusion ring to maintain its simple, easy-to-manufacture form while adding targeted flow control features only where gas escape is needed, preserving both manufacturability and vibration prevention reliability.

Inventive Principle:

Principle #3Local quality

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 prevents up-and-down movement of the exclusion ring and wafer, thereby avoiding unwanted deposition on the bevel and backside of the wafer during processing, ensuring stable processing of bowed wafers.

Implementation Method 1

trapped wafer edge gas accumulating and building pressure

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentUS20230040885A1Exclusion ring with flow paths for exhausting wafer edge gas

Publication Date: 2023.02.09 LAM RES CORP

AI summary

An exclusion ring for semiconductor wafer processing includes an outer circumferential segment having a first thickness and an inner circumferential segment having a second thickness, with the first thickness being greater than the second thickness. The top surface of an inner circumferential segment and the top surface of the outer circumferential segment define a common top surface for the exclusion ring. A plurality of flow paths is formed within the outer circumferential segment, with each of the flow paths extending radially through the plurality of flow paths provides for exhaust of a wafer edge gas from the pocket where a wafer has an edge thereof disposed below part of the inner circumferential portion. The exhausting of the wafer edge gas from the pocket prevents up-and-down movement of the exclusion ring when bowed wafers are processed.