CMP Polishing Pad Grooves Bottom Surface Wafer Edge Planarity
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Solution Overview
Problem
Existing Chemical Mechanical Polishing (CMP) processes face challenges in achieving uniform removal rates and planarity across the entire wafer surface, with the edge regions often having lower removal rates and reduced CMP planarity due to the stiffness of the polishing pad.
Innovation Solution
The CMP apparatus incorporates a polishing pad with a top layer having grooves on its bottom surface, which reduces the overall stiffness of the pad while maintaining local island stiffness, allowing the rebounded location of the pad to move closer to the wafer edge, thereby improving removal rate uniformity and CMP planarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the polishing pad is made stiffer to maintain structural integrity, then the pad can maintain its shape during rotation, but the rebounded location moves away from the wafer edge, reducing removal rate uniformity
Solution Approach 1:
The polishing pad is divided into multiple segments through grooves formed on the bottom surface, creating isolated islands that can independently rebound and contact the wafer edge, improving removal rate uniformity while maintaining overall structural integrity
Solution Approach 2:
Different regions of the polishing pad are given different properties through the groove pattern, with the grooves creating localized flexible islands in regions that need to rebound to the wafer edge, while the overall pad structure maintains sufficient stiffness for structural integrity
2Manufacturing precision
If the polishing pad is made more flexible to improve contact with wafer edge, then removal rate uniformity improves, but the pad loses structural stability during rotation
Solution Approach 1:
The pad structure is segmented into isolated islands by grooves, allowing localized flexibility for wafer edge contact while the overall segmented structure maintains rotational stability through distributed support
Solution Approach 2:
The polishing pad uses a composite structure combining a porous base layer with a non-porous top layer, where the grooves are formed only in the top layer, creating a composite structure that balances flexibility and stability
Data Source
AI summary
A polishing pad is provided. The polishing pad includes a base layer, a top layer, and multiple grooves. The top layer is located over the base layer and has a polishing surface and a bottom surface opposite to each other. The bottom surface is connected to the base layer. The grooves are formed on the bottom surface of the top layer.