Polishing Pad Polyol Ratio for Center Slow Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional polishing pads face issues with center slow phenomenon, where the center of a wafer is poorly polished due to clogging of grooves and fine openings with abrasive grains and dressing waste, leading to reduced polishing rate and longevity.
Innovation Solution
A polishing pad with a polyurethane foam layer having a specific ratio of high-molecular-weight polyols (A/B ratio of 10/90 to 50/50) and a chain extender, which reduces specific gravity while maintaining hardness, preventing clogging and enhancing dressing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the polishing pad uses conventional polyurethane foam with hydrophilic groups or mixed hydrophilic substances to increase slurry retention, then the slurry retention is improved, but the physical properties deteriorate due to unreacted polyol components or non-uniform mixing
Solution Approach 1:
The invention changes the molecular weight parameters of the polyol components, using high-molecular-weight polyols (number-average molecular weight 2,000-10,000) instead of conventional lower molecular weight polyols. This parameter change prevents unreacted polyol from remaining in the cured foam, eliminating the plasticizing effect while maintaining slurry retention through the foam structure itself
Solution Approach 2:
The invention uses a composite polyol system comprising multiple high-molecular-weight polyol components with different molecular weights (2,000-10,000 and 10,000-20,000) in specific ratios. This composite approach ensures complete reaction with isocyanate groups while creating a uniform foam structure that retains slurry effectively without compromising physical property uniformity
2Productivity
If the polishing pad increases polishing rate by using higher elastic modulus material, then the polishing rate is improved, but the planarity and uniformity deteriorate
Solution Approach 1:
The invention changes the molecular weight parameters of the polyol from conventional low molecular weight (500-2,000) to high molecular weight (2,000-10,000 and 10,000-20,000). This parameter change creates a foam structure with appropriate cell size distribution that maintains the pad's elastic modulus at optimal levels, preventing both excessive hardness and excessive softness, thereby achieving balance between polishing rate and planarity
Solution Approach 2:
The invention employs a composite polyol system with two different high-molecular-weight polyol components in specific weight ratios (30-70/70-30). This composite structure creates a foam with optimized cell morphology that provides both sufficient elasticity for planarity and adequate hardness for polishing rate, resolving the contradiction between these two performance parameters
3Productivity
If the polishing pad uses low-molecular-weight polyol to increase polishing rate, then the polishing rate is improved, but the longevity and abrasion resistance deteriorate
Solution Approach 1:
The invention changes the molecular weight parameter from low (500-2,000) to high (2,000-10,000 and 10,000-20,000) ranges. High-molecular-weight polyols provide longer polymer chains that create more robust foam cell walls and better crosslinked structures after curing, significantly improving abrasion resistance and longevity while maintaining polishing rate through optimized foam cell morphology
Solution Approach 2:
The invention uses a composite of two high-molecular-weight polyol components with different molecular weight ranges. This composite structure creates a foam with enhanced mechanical properties including improved tensile strength, elongation, and abrasion resistance, while the specific molecular weight distribution maintains appropriate foam cell size for effective polishing performance
4Manufacturing precision
If the polishing pad increases hardness to improve planarity, then the planarity is improved, but the slurry retention and polishing uniformity deteriorate
Solution Approach 1:
The invention uses a composite polyol system with two high-molecular-weight polyol components in optimized ratios. This creates a foam structure with balanced cell wall thickness and cell size distribution that provides sufficient hardness for planarity while maintaining adequate porosity and surface characteristics for effective slurry retention and polishing uniformity
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 effectively prevents center slow, maintains high polishing rate, and extends the longevity of the polishing pad by ensuring easy dressing and effective slurry retention.
Implementation Method 1
a polishing layer consisting of a polyurethane foam having fine cells, wherein a high-molecular-weight polyol component that is a starting component of the polyurethane foam contains a hydrophobic high-molecular-weight polyol A having a number-average molecular weight of 550 to 800 and a hydrophobic high-molecular-weight polyol B having a number-average molecular weight of 950 to 1300
Data Source
AI summary
A polishing pad has an excellent polishing rate and is superior in longevity without generating center slow. A method of manufacturing a semiconductor device with the polishing pad is also provided. The polishing pad has a polishing layer consisting of a polyurethane foam having fine cells, wherein a high-molecular-weight polyol component that is a starting component of the polyurethane foam contains a hydrophobic high-molecular-weight polyol A having a number-average molecular weight of 550 to 800 and a hydrophobic high-molecular-weight polyol B having a number-average molecular weight of 950 to 1300 in an A/B ratio of from 10/90 to 50/50 by weight.