Retaining Ring Shaped Profile for CMP Pad Protection
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes face challenges in minimizing damage to polishing pads due to sharp edges on retaining rings, leading to reduced pad lifespan and increased risk of substrate defects.
Innovation Solution
The design of a retaining ring with rounded or chamfered corners and channels that reduce sharp edges, allowing for slurry flow and minimizing contact damage to the polishing pad, constructed from durable and chemically inert materials with a combination of rigid and compressible components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a retaining ring with sharp edges is used during CMP, then the substrate is securely held in place, but the polishing pad suffers damage and lifespan is reduced
Solution Approach 1:
The retaining ring corners are rounded with a specified radius of curvature (e.g., 0.020 inches to 0.060 inches) instead of having sharp edges. This curvature prevents the retaining ring from concentrating stress on specific points of the polishing pad, thereby reducing pad damage and extending its operational life while maintaining substrate holding stability
2Productivity
If channels are added to the retaining ring bottom surface, then slurry flow is improved, but the device complexity increases
Solution Approach 1:
The bottom surface of the retaining ring is segmented into multiple channels that extend from the inner diameter to the outer diameter. These channels divide the slurry flow path into discrete segments, improving slurry distribution and flow efficiency under the substrate while maintaining a relatively simple overall ring structure
3Object-affected harmful factors
If the retaining ring corners are rounded, then contact damage to the polishing pad is minimized, but manufacturing precision requirements increase
Solution Approach 1:
The corner radius is specified within an optimized range (e.g., 0.020 inches to 0.060 inches) that balances pad protection with manufacturability. This parameter optimization ensures sufficient rounding to prevent pad damage while remaining achievable with standard manufacturing tolerances
Data Source
AI summary
Retaining rings with curved surfaces are described. The curved surfaces prevent damage to a fixed abrasive polishing pad when the retaining ring is used in a polishing process. The curved surfaces are on the bottom surface of the ring, such as along the outer diameter and/or along the sidewalls of channels formed in the bottom of the ring.