Modified Polyurethane Polishing Layer for Acidic Slurry Uniformity
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Solution Overview
Problem
Current polyurethane-based polishing pads for semiconductor wafers face challenges in achieving high polishing rates and uniformity, especially with acidic slurries, due to limitations in zeta potential control and surface affinity with abrasive grains.
Innovation Solution
A novel Schiff base-containing chain extender is used to produce a polyurethane with functional groups like carboxylic acid, hydroxyl, and amino groups, which can be modified to achieve a zeta potential of -1.0 mV or less at pH 3.0, enhancing affinity with abrasive grains in both acidic and alkaline slurries through surface treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polyurethane materials are used for polishing pads, then the structure is simple and manufacturing is easy, but the polishing rate and uniformity are insufficient especially with acidic slurries
Solution Approach 1:
The patent uses composite materials by combining polyurethane with specific functional additives including carboxylic acid groups, hydroxyl groups, and amino groups. This composite approach enables the polishing pad to achieve high polishing rates with acidic slurries while maintaining structural integrity and performance uniformity.
Solution Approach 2:
The patent applies parameter changes by controlling the zeta potential of the polyurethane surface to be -1.0 mV or less at pH 3.0. This specific parameter optimization enhances the affinity with abrasive grains in acidic slurries, directly improving the polishing rate and uniformity without excessive structural complexity.
2Reliability
If the zeta potential is not optimized, then the polyurethane structure remains simple, but the affinity with abrasive grains in acidic slurry is poor
Solution Approach 1:
The patent optimizes the zeta potential parameter to -1.0 mV or less at pH 3.0 through controlled incorporation of functional groups. This parameter control ensures reliable affinity with abrasive grains in acidic slurries while maintaining a manageable level of surface property complexity.
Solution Approach 2:
The patent applies local quality by introducing specific functional groups (carboxylic acid, hydroxyl, amino) at the surface level of the polyurethane. This localized functionalization enhances affinity with abrasive grains without requiring complex bulk structure modifications.
3Manufacturing precision
If functional groups are added to improve polishing performance, then polishing rate and uniformity improve, but the manufacturing process becomes more complex
Solution Approach 1:
The patent achieves high polishing uniformity by controlling the zeta potential parameter and functional group incorporation during the polyurethane synthesis process. This approach integrates performance optimization into the existing manufacturing workflow rather than requiring separate complex post-processing 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 modified polyurethane polishing pads exhibit improved polishing characteristics, including higher polishing rates and uniformity, by optimizing surface properties and zeta potential, even with acidic slurries, thereby addressing the limitations of existing technologies.
Implementation Method 1
a zeta potential of -1.0 mV or less at pH 3.0, enhancing affinity with abrasive grains
Data Source
AI summary
A Schiff base-containing chain extender may be a diol having a Schiff base or a derivative thereof, as well as a polyurethane produced using the same and a modification method thereof, and a polishing layer including a polyurethane and a polishing method using the polishing layer.