CMP Carrier Head Shims for Retaining Ring Wear

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Solution Overview

Problem

Retaining rings in chemical mechanical polishing (CMP) systems are expensive and require frequent replacement due to wear, necessitating a method to extend their lifespan without compromising polishing performance.

Innovation Solution

A carrier head design incorporating stacked shims between the base and retaining ring, allowing for adjustable positioning and material composition to maintain proper mechanical interaction with the polishing pad, thereby extending the retaining ring's lifespan by compensating for wear through shim insertion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a retaining ring is used in a CMP carrier head, then the substrate can be retained and polishing can be performed, but the retaining ring wears away and requires frequent replacement

Engineering Contradiction:

Improvepolishing performanceVSAvoidretaining ring lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

A shim is introduced as an intermediary component between the base and the retaining ring. This shim absorbs the wear that would otherwise occur on the retaining ring's bottom surface, allowing the retaining ring to maintain its polishing performance without wearing away. The shim acts as a sacrificial element that protects the more critical retaining ring component.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The shim is designed to be a disposable component that is discarded after absorbing a certain amount of wear. By discarding the inexpensive shim rather than the expensive retaining ring, the system recovers and reuses the retaining ring multiple times. This follows the principle of discarding less critical components to preserve more critical ones.

Inventive Principle:

Principle #34Discarding and recovering

2Duration of action of stationary object

If multiple shims are stacked to extend retaining ring life, then the retaining ring lifespan increases, but the device complexity increases

Engineering Contradiction:

Improveretaining ring lifespanVSAvoidcarrier head structure

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The shim system is segmented into multiple individual shim layers that can be stacked. Each shim is a simple, thin disc-shaped component. By segmenting the shim into multiple thin layers rather than using one thick shim, the system achieves greater adjustability and extends retaining ring life while keeping each individual component simple and easy to manufacture.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shim stack provides a dynamic adjustment mechanism. As wear occurs, shims can be added or removed to maintain the correct positioning and contact pressure of the retaining ring. This dynamic adaptability allows the system to compensate for wear over time without requiring complex mechanical adjustments or redesigns.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9272387B2Carrier head with shims

Publication Date: 2016.03.01 APPLIED MATERIALS INC

AI summary

A carrier head includes a base, a substrate mounting surface, a retaining ring secured to the base, and a plurality of stacked shims located between the base and the retaining ring. The retaining ring has a bottom surface for contacting a polishing pad during polishing.