Fluoropolymer Composite CMP Polishing Pad for 3D NAND Removal Rate
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Solution Overview
Problem
Current Chemical Mechanical Planarization (CMP) processes for 3D NAND manufacturing are bottlenecked by slow removal rates during the planarization of thick dielectric layers, primarily due to limitations in conventional polishing pad designs and slurries, which result in lengthy process times and increased defectivity.
Innovation Solution
A polymer-polymer composite polishing pad with a polymeric matrix and embedded fluoropolymer particles is developed, where the fluoropolymer particles have a lower tensile strength than the matrix, allowing for enhanced adsorption of slurry particles and formation of a thin, negatively charged film on the pad surface, improving removal rates and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing pads are used with existing processes and ceria slurries, then the CMP process can be maintained with current equipment, but the removal rate remains too slow for thick PMD layers in 3D NAND manufacturing
Solution Approach 1:
The polishing pad uses a composite structure combining a polymeric matrix with embedded fluoropolymer particles. The fluoropolymer particles have lower tensile strength than the matrix, allowing them to be selectively removed during conditioning to expose fresh particles and maintain a reactive surface. This composite design enables higher removal rates by enhancing slurry particle adsorption and reaction efficiency without compromising pad structural integrity.
2Productivity
If the fluoropolymer particles are made with lower tensile strength than the polymeric matrix, then enhanced adsorption of slurry particles and formation of thin film is achieved, but the pad structure becomes more complex
Solution Approach 1:
The polishing pad implements local quality by having fluoropolymer particles with specific lower tensile strength properties distributed within the polymeric matrix. This creates zones of differential mechanical properties where the fluoropolymer particles can be selectively removed during conditioning while the matrix maintains overall pad integrity. The local variation in tensile strength enables enhanced slurry interaction at the surface while preserving bulk structural stability.
3Productivity
If higher removal rates are achieved through process conditions and slurry design, then the bottleneck in 3D NAND manufacturing is addressed, but defectivity increases and process stability deteriorates
Solution Approach 1:
The polishing pad performs self-service through the differential tensile strength mechanism where fluoropolymer particles are automatically exposed during the conditioning process. As the pad is conditioned, the weaker fluoropolymer particles are selectively removed, continuously exposing fresh fluoropolymer surfaces that maintain high slurry adsorption capacity. This self-regenerating surface ensures consistent removal rates and process stability without requiring external intervention or complex control systems.
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 CMP pad achieves significant increases in removal rates while maintaining low defectivity by optimizing the interaction between the pad and slurry particles, stabilizing the slurry, and reducing particle precipitation, thus enhancing the efficiency and effectiveness of the CMP process.
Implementation Method 1
enhanced adsorption of slurry particles and formation of a thin, negatively charged film on the pad surface
Implementation Method 2
diamond abrasive materials cut the fluoropolymer particles
Data Source
AI summary
The invention provides a polymer-polymer composite polishing pad comprising a polishing layer having a polishing surface for polishing or planarizing a substrate. A polymeric matrix forms the polishing layer. Fluoropolymer particles are embedded in the polymeric matrix. Wherein diamond abrasive materials cut the fluoropolymer particles and rubbing the cut fluoropolymer against a patterned silicon wafer forms a thin film covering at least a portion of the polishing layer and the thin film has a zeta potential more negative than the polymeric matrix at a pH of 7. The polishing surface formed from rubbing with the wafer has a fluorine concentration at a penetration depth of 1 to 10 nm of at least ten atomic percent higher than the bulk fluorine concentration at a penetration depth of 1 to 10 μm.