CMP Pad Integral Window Material Design
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Solution Overview
Problem
Conventional chemical mechanical polishing pads with plug-in-place windows suffer from leakage issues, while those with integral windows experience increased polishing defects due to window bulging, leading to substrate scratching and other defects.
Innovation Solution
A chemical mechanical polishing pad with an integral window formed from a polyurethane reaction product of a curative agent and an isocyanate-terminated prepolymer polyol, having a specific stoichiometric ratio and low porosity, which is integrated within the polishing layer and exhibits a controlled compression set, reducing leakage and bulging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If plug-in-place windows are used in polishing pads, then transparency for optical measurement is improved, but polishing medium leakage occurs at the interface between window and pad
Solution Approach 1:
The window is integrated directly into the polishing pad matrix as an integral window, eliminating the interface between separate components. This merging of the window and pad into a single monolithic structure prevents polishing medium leakage while maintaining optical transparency for measurement.
2Reliability
If integral windows are used in polishing pads, then polishing medium leakage is reduced, but window bulging occurs causing polishing defects
Solution Approach 1:
The physical and chemical parameters of the window material are optimized by selecting specific polymers with appropriate durometers (40-80 Shore A) and controlling crosslinking density. This parameter optimization allows the window to maintain structural stability and resist bulging while remaining integrated in the polishing pad.
Solution Approach 2:
The polishing pad is constructed as a composite structure with multiple layers (polishing layer, subpad layer, buffer layer) where each layer has specific material properties. The window is embedded within this composite structure, allowing the surrounding materials to provide structural support and prevent window bulging.
3Manufacturing precision
If window material is made softer to reduce bulging, then polishing defects are reduced, but window structural stability deteriorates
Solution Approach 1:
The durometer of the window material is precisely controlled within the range of 40-80 Shore A, representing an optimal parameter window that balances softness (to reduce bulging) with structural stability. Additionally, crosslinking density is controlled to further modulate the mechanical properties of the polymer window material.
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 minimizes polishing defects and leakage, maintaining a stable polishing surface with reduced substrate scratching and improved planarization, as demonstrated by lower scratch counts and minimal window bulging during extended polishing sessions.
Implementation Method 1
the integral window is a polyurethane reaction product of a curative agent and an isocyanate-terminated prepolymer polyol; wherein the curative agent contains curative amine moieties that react with the unreacted NCO moieties contained in the isocyanate-terminated prepolymer polyol to form the integral window
Implementation Method 2
The carrier assembly provides a controllable pressure to the wafer, pressing it against the polishing pad
Implementation Method 3
a chemical composition ('slurry') or other polishing solution is provided between the wafer and the polishing pad
Data Source
AI summary
A chemical mechanical polishing pad having a polishing layer with an integral window and a polishing surface adapted for polishing a substrate selected from a magnetic substrate, an optical substrate and a semiconductor substrate, wherein the formulation of the integral window provides improved defectivity performance during polishing. Also provided is a method of polishing a substrate using the chemical mechanical polishing pad.