Water-Based Polishing Pad for CMP Defect Reduction
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Solution Overview
Problem
Conventional polishing pads for chemical mechanical planarization (CMP) face issues with density and porosity variations, leading to inconsistent polishing performance, delamination, and high manufacturing costs, particularly in the production of 'hard' pads from casting and skiving methods, and 'soft' pads from solvent-based coagulation processes.
Innovation Solution
A water-based polishing pad with a polymeric matrix containing microspheres or porosity, formed from a blend of urethane and acrylic dispersions applied to a permeable substrate, is manufactured using a continuous web-format process, eliminating the need for adhesives and reducing pad-to-pad variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If casting and skiving method is used to manufacture hard polishing pads, then polishing pad density and porosity can be controlled, but pad-to-pad variations and center-to-edge variations occur leading to inconsistent polishing performance
Solution Approach 1:
The patent changes the manufacturing parameters from batch casting/skiving to continuous web-format coagulation, transforming the production process to eliminate variations. This continuous process maintains consistent density and porosity parameters across all pads, resolving the inconsistency issue.
Solution Approach 2:
The web-format coagulation process ensures homogeneous distribution of porosity and density throughout the polishing pad. By forming pads continuously from a uniform polymer solution, the patent achieves homogeneity that eliminates the center-to-edge and pad-to-pad variations inherent in casting methods.
2Manufacturing precision
If solvent-based coagulation process is used to form soft polishing pads, then pad uniformity is improved, but organic solvent handling becomes cumbersome and cost prohibitive
Solution Approach 1:
The patent changes the solvent parameter from organic (N,N-dimethyl formamide) to water-based polymer dispersions. This parameter change maintains the coagulation process benefits for pad uniformity while eliminating the cumbersome and costly organic solvent handling issues.
3Strength
If pressure-sensitive adhesive is used to bond layers in laminated polishing pads, then layer bonding is achieved, but delamination occurs during polishing due to low bonding strength and marginal chemical resistance
Solution Approach 1:
The patent extracts and eliminates the pressure-sensitive adhesive layer from the laminated pad structure. By removing this problematic intermediate layer, the patent avoids the delamination issues while maintaining layer bonding through direct integration of the polishing layer onto the support pad.
Solution Approach 2:
The patent uses composite materials where the polishing layer and support pad are integrated through direct bonding without adhesive intermediaries. This composite structure provides superior chemical resistance and bonding strength, preventing delamination during polishing operations.
4Manufacturing precision
If conventional casting and skiving method is used, then hard polishing pads with consistent reproducible polishing properties can be manufactured, but polishing variations arise from casting location
Solution Approach 1:
The patent replaces the mechanical casting and skiving process with a chemical coagulation process in web format. This substitution eliminates the mechanical variations introduced by different casting locations while maintaining consistent and reproducible polishing properties through controlled chemical forming.
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 provides a polishing pad with reduced defectivity, improved uniformity, and cost-effectiveness, while enhancing mechanical and chemical adhesion properties, resulting in consistent polishing performance across semiconductor processing applications.
Implementation Method 1
a polymeric matrix having porosity or filler dispersed therein, the polymeric matrix being formed of a blend of a urethane and acrylic dispersion
Implementation Method 2
coagulating polymers utilizing a solvent/non-solvent process to form polishing pads in a web format
Implementation Method 3
the polymeric matrix is applied on a permeable substrate
Data Source
AI summary
A method for polishing a substrate using a pad comprising, a polymeric matrix having microspheres dispersed therein, the polymeric matrix being formed of a water-based polymer or blends thereof, wherein the polymeric matrix is applied on a permeable substrate, and wherein the polishing pad exhibits reduced defectivity and improved polishing performance are provided.