Retainer Ring Non-Uniform Thickness for CMP Wear
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Solution Overview
Problem
The existing retainer rings in CMP apparatuses experience uneven wear, leading to increased clearance between the semiconductor wafer and the retainer ring, reducing pressure effectiveness and shortening the retainer ring's lifespan, as high pressure accelerates wear and reduces contact area, causing uneven polishing profiles.
Innovation Solution
The retainer ring is designed with concentric grooves that increase the contact area on the inner peripheral side relative to the outer peripheral side, centered on an imaginary pressure center, reducing uneven wear and maintaining effective pressure distribution, thereby extending the retainer ring's lifespan and ensuring consistent polishing profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high pressure is applied to the retainer ring to maintain polish profile, then the polish profile is improved, but the wear of the retainer ring accelerates
Solution Approach 1:
The retainer ring is designed with non-uniform thickness, being thicker at the outer peripheral side and thinner at the inner peripheral side. This local variation in thickness creates different contact areas with the polish pad across the retainer ring, optimizing pressure distribution to maintain polish profile while reducing overall wear and extending lifespan.
2Manufacturing precision
If the diametrical width of the retainer ring is reduced to inhibit clearance increase, then clearance is controlled, but the contact area with polish cloth is reduced requiring increasingly high pressure
Solution Approach 1:
The retainer ring employs non-uniform thickness distribution with the outer peripheral side being thicker than the inner peripheral side. This design optimizes the contact area with the polish pad, ensuring sufficient contact for effective polishing while controlling clearance, thereby eliminating the need for increasingly high pressure and extending retainer ring lifespan.
3Manufacturing precision
If high pressure is applied to the retainer ring to obtain desired polish profile, then the polish profile is improved, but the wear of the retainer ring becomes uneven
Solution Approach 1:
The retainer ring is designed with non-uniform thickness, being thicker at the outer peripheral side and thinner at the inner peripheral side. This local variation creates optimized pressure distribution across the contact surface, maintaining desired polish profile while ensuring even wear patterns that extend the retainer ring's operational life.
Data Source
AI summary
A retainer ring configured to be attachable, at a first side thereof, to a polish head of a polish apparatus configured to polish a polish object by depressing the polish object against a polish pad is disclosed. The retainer ring is configured to depress the polish pad at a second side thereof. The retainer ring includes a contact surface contacting the polish pad. The contact surface applies depressing force on the polish pad. The depressing force is directed from a polish head side and is applied so as to be centered on an imaginary circle of pressure center having a radius falling substantially in a middle of an inner radius of the retainer ring and an outer radius of the retainer ring. An area of the contact surface is greater in a first region inside the circle of pressure center than in a second region outside the circle of pressure center.