Flexible Membrane Retaining Ring for CMP Load Control

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Solution Overview

Problem

Existing chemical mechanical polishing (CMP) technologies face challenges in maintaining consistent loading on the polishing pad due to carrier distortion, leading to uneven wear and process variability, which affects the substrate edge and reduces the lifetime of retaining rings.

Innovation Solution

A retaining ring assembly with a flexible membrane and a carrier head design that includes an annular chamber and concentric recesses, allowing independent control of the load on the retaining ring, reducing carrier distortion and enabling lower polishing pressures, while the flexible membrane is secured to the retaining ring with fasteners and formed of elastic material like silicone.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a rigid carrier head is used to provide stable support during polishing, then structural stability is improved, but carrier distortion occurs leading to uneven loading on the polishing pad

Engineering Contradiction:

Improvestructural stabilityVSAvoidloading uniformity

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent employs a flexible membrane as a carrier head that can deform elastically under polishing loads. This flexible membrane is secured to a rigid support structure, allowing it to accommodate variations in substrate thickness and polishing pressure without causing carrier distortion. The flexible membrane's ability to flex while maintaining structural integrity ensures uniform loading on the polishing pad, resolving the contradiction between structural stability and loading uniformity.

Inventive Principle:

Principle #30Flexible shells and thin films

2Productivity

If higher polishing pressure is applied to improve polishing performance, then productivity is improved, but carrier distortion increases causing uneven wear on the retaining ring

Engineering Contradiction:

Improvepolishing performanceVSAvoidretaining ring lifetime

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The flexible membrane carrier head can withstand higher polishing pressures by deforming elastically, distributing the load uniformly across the polishing pad. This prevents carrier distortion that would otherwise cause uneven wear on the retaining ring. The flexible membrane's elastic properties allow it to absorb polishing stresses without transmitting distortion to the retaining ring, thereby extending its service life while maintaining high polishing performance.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The flexible membrane acts as an intermediary between the polishing pad and the substrate, decoupling the rigid support structure from the polishing interface. This intermediary layer absorbs and distributes polishing forces, preventing direct transmission of distortion to the retaining ring. The flexible membrane mediates the interaction between high polishing pressures and the retaining ring, allowing high productivity without compromising retaining ring durability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stability of the object's composition

If the carrier head is made more rigid to reduce distortion, then structural stability is improved, but the ability to accommodate substrate variations is reduced

Engineering Contradiction:

Improvecarrier stabilityVSAvoidsubstrate accommodation capability

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The flexible membrane provides both stability and adaptability simultaneously. It maintains structural stability through its connection to the rigid support while providing substrate accommodation capability through its elastic deformation. The flexible membrane can conform to varying substrate thicknesses and surface profiles, adapting to different polishing conditions without compromising carrier stability. This dual functionality resolves the contradiction between carrier stability and substrate accommodation capability.

Inventive Principle:

Principle #30Flexible shells and thin films

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 design ensures consistent loading on the polishing pad, reduces uneven wear on the retaining ring, and extends its lifetime by minimizing carrier distortion and process variability, allowing for more precise control during CMP processes.

Implementation Method 1

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

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentEP1925398B1Retaining ring, flexible membrane for applying load to a retaining ring, and retaining ring assembly

Publication Date: 2011.03.30 APPLIED MATERIALS INC

Figure 1
Figure 2A~2D
Figure 3A~3B

AI summary

A carrier head that has a base assembly, a retaining ring assembly, a carrier ring, and a flexible membrane is described. A retaining ring assembly has a flexible membrane (300) shaped to provide an annular chamber and an annular retaining ring (200), wherein annular concentric projections of the flexible membrane are sized to fit into annular concentric recesses of the annular retaining ring.