CMP Polyurethane Film Composition for Stable Zeta Potential
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Solution Overview
Problem
Existing polyurethane films used in chemical mechanical planarization (CMP) polishing applications face challenges with non-uniform polishing performance due to variations in thickness and zeta potential, which are influenced by the migration and diffusion of additives, leading to inconsistent polishing results and reduced removal rates.
Innovation Solution
A polyurethane composition is developed with multifunctional amines covalently bonded into the backbone, stabilizing zeta potential and preventing additive migration, using a reactive mixture with a mole ratio of isocyanate groups to hydroxyl groups of 0.98 or greater, ensuring uniform thickness and enhanced polishing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyurethane films are used in CMP polishing applications, then the polishing process can be performed, but non-uniform polishing performance occurs due to variations in thickness and zeta potential caused by additive migration and diffusion
Solution Approach 1:
The patent removes problematic small molecule additives from the polyurethane composition. Instead of using separate additives that migrate and diffuse, the desired functionalities (zeta potential control, thickness uniformity) are achieved through the polyurethane backbone structure itself and the controlled reaction stoichiometry, eliminating the source of non-uniformity.
Solution Approach 2:
The patent creates a composite polyurethane system by combining multiple components (polyol, diol chain extender, diisocyanate, mono-alcohol, multifunctional amine) in specific ratios. This composite approach allows the system to achieve both mechanical properties and electrostatic properties (zeta potential) through the integrated molecular structure rather than separate additives.
2Productivity
If polyurethane films with additives are used to achieve desired zeta potential and thickness, then polishing can proceed, but the additives migrate and diffuse causing inconsistent polishing results and reduced removal rates
Solution Approach 1:
The patent establishes the correct isocyanate-to-hydroxyl ratio (0.98 or greater) before film formation and polishing operation. This preliminary stoichiometric control ensures that the zeta potential and thickness are uniform from the start, preventing the need for corrective actions during polishing and maintaining consistent removal rates throughout the pad's service life.
Solution Approach 2:
The patent changes the critical parameter of isocyanate-to-hydroxyl mole ratio to 0.98 or greater. This specific parameter change fundamentally alters the polyurethane film properties, resulting in stable zeta potential and uniform thickness that maintain consistent polishing performance and high removal rates without additive migration issues.
3Manufacturing precision
If conventional polyurethane synthesis is used, then film fabrication is achieved, but variations in thickness and zeta potential lead to non-uniform polishing performance
Solution Approach 1:
The patent precisely controls the isocyanate-to-hydroxyl mole ratio parameter at 0.98 or greater during synthesis. This precise parameter control ensures uniform polymerization throughout the film, resulting in consistent thickness and stable zeta potential that translate to reliable, uniform polishing performance across the entire polishing pad surface.
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 provides a polyurethane film with stable zeta potential and uniform thickness, improving polishing consistency and increasing removal rates by attracting abrasive particles, thus enhancing CMP process efficiency.
Implementation Method 1
multifunctional amines covalently bonded into the backbone, stabilizing zeta potential and preventing additive migration
Implementation Method 2
improving polishing consistency and increasing removal rates by attracting abrasive particles
Data Source
AI summary
Polyurethanes and polishing articles made therefrom including a reaction product of a reactive mixture including a polyol, a diol chain extender, a diisocyanate, a mono-alcohol, and a multifunctional amine are described. The mole ratio of isocyanate groups to hydroxyl groups in the reactive mixture is 0.98 or greater. Such polyurethanes may remain stable even at extended exposure to elevated reactive extrusion temperatures.