Thermoset Polyurethane Polishing Pad for Wafer Flatness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polishing pads for semiconductor wafers and glass substrates often generate tiny undulations on the polished surface, which are difficult to eliminate, affecting the surface flatness and polishing efficiency.
Innovation Solution
A polishing pad with a thermoset polyurethane foam layer composed of isocyanate components, active-hydrogen-containing compounds, including polyol compounds with two or more functional groups and a monool compound with one functional group, forming substantially spherical bubbles with an average diameter of 20 to 300 μm, enhancing adhesiveness and maintaining hardness to reduce undulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the polishing layer is made softer to improve surface finish, then surface roughness decreases, but the polishing rate and planarization characteristics deteriorate
Solution Approach 1:
The patent optimizes the molecular weight and functional group content of polyol compounds, along with the ratio of isocyanate to active hydrogen-containing compounds. These parameter changes adjust the foam's hardness and elasticity to maintain high polishing rate while achieving low surface roughness
Solution Approach 2:
The invention utilizes a porous foam structure with controlled cell size and distribution. The porous structure provides cushioning effect for surface finish while maintaining adequate rigidity for polishing rate and planarization characteristics through proper foam density control
2Manufacturing precision
If a polyurethane foam is used to decrease tiny undulations, then surface flatness is improved, but the adhesiveness and durability of the polishing layer are reduced
Solution Approach 1:
The patent creates a composite polyurethane system where polyether polyol and polyester polyol work synergistically. This composite material structure maintains strong adhesiveness to the substrate while reducing tiny undulations through controlled foam expansion and cell structure
Solution Approach 2:
The invention adjusts the functional group value of polyol compounds and the NCO index to optimize the crosslinking density of the cured polyurethane. This parameter optimization ensures strong substrate adhesion while achieving the desired surface flatness through reduced tiny undulations
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 polishing pad effectively decreases tiny undulations on the polished surface while maintaining high planarization characteristics and polishing rate stability over time, improving the finish quality of semiconductor wafers and glass substrates.
Implementation Method 1
a polishing pad having a polishing layer which comprises a thermoset polyurethane foam
Implementation Method 2
the thermoset polyurethane foam contains, as raw material components, an isocyanate component, and active-hydrogen-containing compounds
Data Source
AI summary
A polishing pad having a polishing layer comprising a thermoset polyurethane foam, wherein the thermoset polyurethane foam contains, as raw material components, an isocyanate component, and active-hydrogen-containing compounds, and the active-hydrogen-containing compounds comprise one or more polyol compounds (each) having two or more functional groups, and a monool compound having one functional group.