Polyurethane-Polyurea Polishing Pad for Semiconductor Wafer
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Solution Overview
Problem
Conventional hard (dry) polishing pads for semiconductor devices cause scratches and have a high likelihood of clogging, while soft (wet) polishing pads provide better polishing rate and uniformity but fail to maintain a consistent polishing state due to anisotropic cell shapes and low-density portions tearing off.
Innovation Solution
A polishing pad with a polyurethane-polyurea resin foam having a Young's modulus of 450 to 30000 kPa and a density of 0.30 to 0.60 g/cm³, manufactured using an isocyanate group-containing compound, polyisocyanate compound, polyamine compound, and aqueous dispersion, which suppresses strong pressing and clogging, and maintains a consistent polishing state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard polishing pad molded by the dry method is used, then rigidity for keeping flatness is improved, but scratches on the workpiece surface increase
Solution Approach 1:
The patent changes the physical parameters of the polishing pad by controlling the cell diameter (50-200 μm) and density (0.4-0.6 g/cm³) of the urethane resin foam, achieving optimal balance between rigidity and scratch reduction through parameter optimization
Solution Approach 2:
The patent uses a composite structure combining a hard polishing layer (molded by dry method) with a soft supporting layer (molded by wet method), where the hard layer provides rigidity for flatness while the soft layer reduces scratches through its suede-type openings and lower hardness
2Strength
If a hard polishing pad molded by the dry method is used, then rigidity for keeping flatness is improved, but clogging probability increases
Solution Approach 1:
The patent optimizes the cell diameter parameter to 50-200 μm, which is larger than conventional small cells, providing sufficient space for slurry retention and flow while maintaining the rigidity needed for flatness, thereby reducing clogging
Solution Approach 2:
The patent utilizes the porous structure of the urethane resin foam with controlled cell diameter and density to create adequate slurry pathways, preventing clogging while maintaining structural rigidity through the foam architecture
3Productivity
If a soft polishing layer molded by the wet method is used, then polishing rate and uniformity are improved, but the polishing state cannot be maintained for a long period
Solution Approach 1:
The patent divides the polishing pad into two functional segments: a hard polishing layer (dry method) that provides durability and maintains polishing state, and a soft supporting layer (wet method) that ensures polishing rate and uniformity, with each layer performing its specialized function
Solution Approach 2:
The patent achieves homogeneous distribution of cell sizes (50-200 μm) and uniform density (0.4-0.6 g/cm³) throughout the polishing layer, ensuring consistent polishing performance and state maintenance over time
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 reduces scratches and clogging, enhances polishing rate and uniformity, and maintains a consistent polishing state for a longer period, allowing its use for both primary and finish processing.
Implementation Method 1
a urethane resin foam is molded by curing a prepolymer containing an isocyanate group-containing compound based on a reaction with a curing agent (dry method)
Data Source
Figure 1
AI summary
Provided are a polishing pad which remedies the problem of scratches occurring when a conventional hard (dry) polishing pad is used, which is excellent in polishing rate and polishing uniformity, and which can be used for not only primary polishing but also finish polishing, and a manufacturing method therefor. The polishing pad is a polishing pad for polishing a semiconductor device, comprising a polishing layer having a polyurethane-polyurea resin foam containing substantially spherical cells, wherein the polyurethane-polyurea resin foam has a Young's modulus E in a range from 450 to 30000 kPa, and a density D in a range from 0.30 to 0.60 g/cm3.