Polishing Pad Composite Structure to Reduce Scratches and Particles
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Solution Overview
Problem
Conventional polishing pads struggle to produce high-precision mirror finished surfaces for silicon bare wafers, glass, and compound semiconductor substrates without causing defects like scratches and particles, and they are inadequate for polishing a large number of surfaces effectively.
Innovation Solution
A polishing pad is developed using a nonwoven fabric of ultrafine fibers with an average monofilament diameter of 3.0 μm to 8.0 μm, impregnated with a polyurethane-based elastomer in a specific range, and laminated with a porous polyurethane layer having controlled opening diameters and compression elastic modulus, preventing fiber exposure and ensuring uniform stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polishing pads with porous polyurethane surface layers are used, then polishing capability is provided, but fiber exposure causes scratches and particles on mirror finished surfaces
Solution Approach 1:
The patent applies a thin film layer (0.5-5 μm) of polyurethane resin over the porous polyurethane surface layer. This thin film acts as a protective barrier that prevents fiber exposure while maintaining the polishing capability of the underlying porous layer, thereby eliminating scratches and particles on mirror finished surfaces.
Solution Approach 2:
The patent creates a composite structure combining multiple layers: a base layer (nonwoven fabric or textile fabric), a porous polyurethane surface layer (30-100 μm) for polishing, and a thin film layer (0.5-5 μm) for protection. This composite material structure integrates the advantages of each layer to achieve both effective polishing and defect-free mirror surfaces.
2Manufacturing precision
If polishing pads are designed for high precision mirror finishing, then surface quality improves, but the number of surfaces that can be polished decreases
Solution Approach 1:
The patent designs the thin film layer as a sacrificial element that wears down during polishing operations. As the thin film gradually wears, it continuously exposes fresh polishing surfaces from the underlying porous polyurethane layer, allowing the pad to maintain mirror finishing capability throughout its service life and increase the number of surfaces that can be polished.
Solution Approach 2:
The patent creates a dynamic surface structure where the thin film layer progressively wears during use, dynamically exposing the porous polyurethane polishing surface beneath. This dynamic wear mechanism allows the polishing pad to adapt and maintain its mirror finishing capability over extended periods, increasing productivity.
3Manufacturing precision
If the porous polyurethane surface layer is made thinner to prevent fiber exposure, then surface quality improves, but polishing capability deteriorates
Solution Approach 1:
The patent segments the polishing pad into distinct functional layers: the porous polyurethane surface layer (30-100 μm) dedicated to polishing, and a separate thin film layer (0.5-5 μm) dedicated to surface protection. This segmentation allows each layer to be optimized independently - the porous layer maintains adequate thickness for polishing capability while the thin film provides the necessary surface protection.
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 reduces defects such as scratches and particles, enabling the polishing of a larger number of surfaces with high precision and maintaining surface quality, thus enhancing the capability for mirror finishing of silicon bare wafers, glass, and compound semiconductor substrates.
Implementation Method 1
a porous polyurethane layer having controlled opening diameters and compression elastic modulus
Implementation Method 2
impregnated with a polyurethane-based elastomer in a specific range
Data Source
AI summary
A polishing pad is provided with a compression elastic modulus of 0.17 MPa or more and 0.32 MPa or less produced by preparing a nonwoven fabric formed of bundles of ultrafine fibers with an average monofilament diameter of 3.0 μm or more and 8.0 μm or less, preparing a polishing pad base by impregnating the nonwoven fabric with a polyurethane based elastomer in an amount of 20 mass % or more and 50 mass % or less relative to the mass of the polishing pad base, and laminating the polishing pad base with a porous polyurethane layer containing wet-solidified polyurethane as primary component which has openings with an average opening diameter of 10 μm or more and 90 μm or less in its surface to serve as polishing surface layer.