CMP Slurry Distribution Barriers for Uniform Pad Coverage
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Solution Overview
Problem
Chemical mechanical polishing processes are sensitive to pattern density, leading to issues like erosion, dishing, and defectivity due to non-uniform slurry distribution and the presence of polishing by-products.
Innovation Solution
A polishing liquid distribution system with barriers to block used slurry and a dispenser to spread fresh slurry uniformly across the polishing pad, reducing the impact of pattern density and improving uniformity by preventing used slurry from returning to the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional slurry distribution is used without barriers, then the polishing process is simpler, but used polishing liquid returns to the polishing surface causing non-uniform slurry distribution and pattern density sensitivity
Solution Approach 1:
The polishing pad surface is segmented into different zones using barriers. The barriers divide the polishing surface into a first region (where fresh slurry is applied) and a second region (where used slurry is blocked), preventing mixing and ensuring uniform slurry distribution across the substrate polishing surface.
Solution Approach 2:
Used polishing liquid is extracted or removed from the polishing cycle by blocking it with barriers before it can return to the polishing surface. This extraction of harmful used slurry prevents re-contamination and maintains consistent polishing conditions.
2Manufacturing precision
If barriers are added to block used slurry, then slurry distribution uniformity improves, but the device complexity and cost increase
Solution Approach 1:
The barrier structure is designed with specific local properties: a leading surface oriented at an acute angle (15-75 degrees) to the polishing surface, a trailing surface, and side surfaces. This localized geometric design optimizes slurry flow control while maintaining manufacturability and reducing overall system complexity.
3Object-affected harmful factors
If barriers contact the polishing surface to block slurry, then used slurry is effectively blocked, but the barriers may interfere with substrate polishing contact
Solution Approach 1:
The barriers are positioned in the radial direction of the polishing pad, extending from the center toward the periphery. This radial positioning allows the barriers to block slurry flow in the tangential direction without interfering with the substrate's contact with the polishing surface, as the barriers operate in a different spatial dimension.
Data Source
AI summary
An apparatus for chemical mechanical polishing includes a rotatable platen having a surface to support a polishing pad, a carrier head to hold a substrate in contact with the polishing pad, and a polishing liquid distribution system. The polishing liquid distribution system includes a dispenser positioned to deliver a polishing liquid to a portion of a polishing surface of the polishing pad, and a curved barrier positioned after the dispenser to spread fresh polishing liquid from the dispenser.