CMP Polishing Pad Protrusion Structure for Scratch Reduction
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Solution Overview
Problem
Existing chemical mechanical polishing (CMP) processes face challenges in achieving uniformity and reducing defects in semiconductor wafers due to non-uniform thickness and sharp edges of protrusions on polishing pads, leading to scratching and reliability issues.
Innovation Solution
The development of polishing pads with multi-material protrusions and varying dimensions, including different materials, pore sizes, and densities, which are softer in peripheral regions to reduce scratching and harder in central regions, improving abrasiveness and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If protrusions on polishing pad have sharp edges and uniform thickness, then abrasiveness is improved, but scratching of wafer increases and reliability deteriorates
Solution Approach 1:
The polishing pad employs protrusions with non-uniform thickness, where the central region has greater thickness than peripheral regions. This creates locally differentiated properties: the thicker central region provides enhanced abrasiveness for effective material removal, while the thinner peripheral regions reduce scratching risk at the wafer edges, thereby resolving the contradiction between abrasiveness and reliability.
2Ease of manufacture
If polishing pad has uniform structure, then manufacturing simplicity is maintained, but wafer uniformity deteriorates due to non-uniform down-force distribution
Solution Approach 1:
The polishing pad features a non-uniform structure with protrusions of varying thickness across different regions (thicker centrally, thinner peripherally). This local differentiation optimizes down-force distribution during polishing, ensuring more uniform contact pressure across the wafer surface, thereby improving wafer uniformity while maintaining reasonable manufacturing complexity through structured design.
3Device complexity
If protrusions have consistent dimensions, then device complexity is reduced, but within-wafer uniformity deteriorates
Solution Approach 1:
The polishing pad implements protrusions with spatially varying dimensions, specifically with the central region containing thicker protrusions and peripheral regions containing thinner protrusions. This graduated dimensional variation enhances within-wafer uniformity by distributing polishing pressure more evenly across the wafer surface, while the systematic nature of the variation keeps the overall structure manageable and not excessively complex.
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
The solution enhances wafer-to-wafer and within-wafer uniformity, reduces device defects, and improves electrical characteristics by minimizing scratching and optimizing down-force distribution, thereby increasing chip yield and reducing downtime.
Implementation Method 1
chemical mechanical polishing (CMP) processes
Implementation Method 2
chemical mechanical polishing (CMP)
Data Source
AI summary
Polishing pads having varying protrusions and methods of forming the same are disclosed. In an embodiment, a polishing pad includes a polishing pad substrate; a first protrusion on the polishing pad substrate, the first protrusion including a central region and a peripheral region surrounding the central region, and a first hardness of the central region being greater than a second hardness of the peripheral region; and a first groove adjacent a first side of the first protrusion.