Polyurethane Polishing Pad Surface Tuning Across Slurry pH
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Solution Overview
Problem
Current polyurethane-based polishing pads for semiconductor wafers face challenges in achieving optimal surface properties for CMP, including limited adjustability of zeta potential and affinity with abrasive grains across different slurry pH levels, leading to suboptimal polishing rates and surface defects.
Innovation Solution
A modification method for polyurethane involving Diels-Alder reactions with compounds having conjugated double bonds to introduce functional groups such as carboxyl, hydroxyl, or amino groups, allowing for controlled zeta potential adjustment and enhanced affinity with abrasive grains in both acidic and alkaline slurry conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional polyurethane materials are used for polishing pads, then basic polishing function is provided, but surface properties such as zeta potential and affinity with abrasive grains cannot be easily adjusted across different slurry pH levels
Solution Approach 1:
The patent applies parameter changes by introducing functional groups (carboxyl, hydroxyl, amino) into the polyurethane polymer chain through Diels-Alder reaction. This modification changes the chemical parameters of the polyurethane, enabling adjustment of zeta potential and surface affinity properties across different pH ranges, thereby resolving the contradiction between maintaining basic polishing function and achieving adjustable surface properties.
Solution Approach 2:
The patent creates a composite material system by combining polyurethane base polymer with functional groups introduced via Diels-Alder reaction. This composite structure integrates the mechanical properties of polyurethane with the surface activity of functional groups, allowing tailored surface properties while maintaining structural integrity, thus resolving the contradiction between adaptability and material complexity.
2Productivity
If the zeta potential of the polishing surface is adjusted to increase affinity with abrasive grains, then polishing rate is improved, but the ability to maintain optimal performance across wide pH ranges is limited
Solution Approach 1:
The patent uses parameter changes by selecting different functional groups (carboxyl for negative zeta potential, amino for positive zeta potential) to achieve desired polishing rates while maintaining performance across pH ranges. The Diels-Alder reaction enables controlled introduction of these functional groups, allowing optimization of both polishing rate and pH adaptability simultaneously.
3Reliability
If polyurethane surface properties are modified to achieve optimal zeta potential, then affinity with abrasive grains improves, but the modification process becomes complex
Solution Approach 1:
The patent replaces complex physical surface modification methods with chemical modification through Diels-Alder reaction. This chemical approach allows precise control of surface properties by selecting specific functional groups, achieving reliable affinity with abrasive grains while simplifying the modification process through a single-step reaction rather than multiple physical treatment steps.
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 method enables polyurethane surface properties to be easily modified, achieving high affinity with abrasive grains across a wide pH range, thereby improving polishing rates and reducing defects, with zeta potential changes of 3 mV or more at pH 5 and across pH 5 to 8.
Implementation Method 1
A modification method for polyurethane involving Diels-Alder reactions with compounds having conjugated double bonds to introduce functional groups such as carboxyl, hydroxyl, or amino groups
Data Source
AI summary
A modification method of a polyurethane, including the steps of: preparing a polyurethane having an ethylenically unsaturated bond; and treating the polyurethane with a liquid containing a compound having a conjugated double bond, or a modification method of a polyurethane, including the steps of: preparing a polyurethane having a conjugated double bond; and treating the polyurethane with a liquid containing a compound having an ethylenically unsaturated bond is used.