CMP Retaining Ring With Flexible Membrane for Load Distribution

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Solution Overview

Problem

Current chemical mechanical polishing (CMP) technologies face challenges in providing consistent and adjustable load distribution during substrate polishing, leading to uneven wear and process variability due to direct securing of the retaining ring to the carrier head, which affects polishing precision and ring lifetime.

Innovation Solution

A retaining ring assembly with a flexible membrane and a carrier ring system that allows independent load adjustment on the polishing pad, featuring a dual-layer construction with a compressible lower portion and a rigid upper portion, and a flexible membrane with annular projections and recesses for secure attachment, enabling controlled pressure distribution and reduced carrier distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the retaining ring is directly secured to the carrier head, then the structure is simple, but the load distribution is uneven and polishing precision deteriorates

Engineering Contradiction:

Improvestructure simplicityVSAvoidpolishing precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

A flexible membrane is introduced as an intermediary component between the retaining ring and the carrier head. This membrane distributes the load uniformly across the retaining ring, preventing the uneven stress concentration that occurs with direct securing, thereby maintaining polishing precision while adding only a single intermediate component.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The retaining ring assembly combines multiple materials with different properties: a rigid retaining ring for structural support, a flexible membrane for uniform load distribution, and a compressible lower portion for cushioning. This composite structure resolves the contradiction by integrating components that collectively achieve both simplicity and precision.

Inventive Principle:

Principle #40Composite materials

2Device complexity

If the retaining ring is directly secured to the carrier head, then the device complexity is low, but the retaining ring lifetime is reduced due to uneven wear

Engineering Contradiction:

Improvedevice complexityVSAvoidretaining ring lifetime

Core Design Contradiction:

Device complexityVSDuration of action of stationary object

Solution Approach 1:

A compressible lower portion is incorporated into the retaining ring assembly to provide beforehand cushioning. This compressible element absorbs and distributes mechanical stresses before they reach the retaining ring, preventing premature wear and extending the retaining ring's operational life while maintaining a relatively simple overall device structure.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Productivity

If higher polishing pressure is applied, then the polishing speed increases, but the wear on the retaining ring becomes more uneven

Engineering Contradiction:

Improvepolishing speedVSAvoidwear uniformity

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

A flexible membrane is used to distribute polishing pressure uniformly across the retaining ring and substrate edge. This flexible component ensures that even at higher polishing pressures, the load is spread evenly, preventing localized stress concentration and maintaining wear uniformity while enabling higher productivity.

Inventive Principle:

Principle #30Flexible shells and thin films

4Productivity

If the load on the substrate edge is increased, then the polishing effectiveness improves, but the carrier distortion increases

Engineering Contradiction:

Improvepolishing effectivenessVSAvoidcarrier distortion

Core Design Contradiction:

ProductivityVSShape

Solution Approach 1:

The flexible membrane acts as an intermediary that decouples the load application from the carrier head. It allows increased load on the substrate edge for improved polishing effectiveness while absorbing and distributing the stresses to minimize carrier distortion, as the membrane's flexibility compensates for carrier deformation.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This solution enhances polishing precision by reducing uneven wear and process variability, allowing for lower polishing pressures and extending the life of the retaining ring while maintaining consistent load on the substrate edge, thereby improving the CMP process.

Implementation Method 1

a flexible membrane shaped to provide an annular chamber positioned beneath the base assembly and above the annular retaining ring

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a compressible lower portion and a rigid upper portion

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS7654888B2Carrier head with retaining ring and carrier ring

Publication Date: 2010.02.02 APPLIED MATERIALS INC

AI summary

A carrier head that has a housing, a base assembly, a retaining ring, a carrier ring, and a flexible membrane is described. The base assembly is vertically movable relative to the housing. The retaining ring is connected to and vertically movable relative to the base assembly and has a lower surface configured to contact a polishing pad and an inner surface configured to circumferentially surround the edge of a substrate to retain the substrate. The carrier ring is connected to and vertically fixed relative to the base assembly, circumferentially surrounds the retaining ring to prevent lateral motion of the retaining ring, and has a bottom surface configured to contact a polishing pad.