Fluorinated Polyurethane Polishing Pad for CMP Defect Reduction
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Solution Overview
Problem
Conventional polishing pads for chemical mechanical planarization (CMP) often result in a high number of defects on substrates, such as scratches and chatter marks, due to the sticking of slurry particles, which affects the quality and yield of semiconductor fabrication.
Innovation Solution
A polishing pad comprising a polyurethane with a fluorinated repeating unit, specifically designed to have a contact angle difference of 1.5 to 5% between pure water and fumed silica slurry, reducing particle adhesion and incorporating a foamed body with controlled pore size and Shore D hardness, is used in conjunction with a sub-pad to minimize defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional polishing pads are used, then polishing process can be performed, but the number of defects on substrate increases due to slurry particle sticking
Solution Approach 1:
The patent modifies the chemical composition parameters of the polishing pad by incorporating fluorinated compounds (specifically perfluoroalkyl groups) into the polyurethane polymer structure. This chemical parameter change alters the surface energy and contact angle characteristics of the polishing pad, reducing slurry particle adhesion and thereby decreasing the number of defects on the substrate while maintaining polishing quality
Solution Approach 2:
The patent creates a composite material structure by combining conventional polyurethane with fluorinated compounds to form a hybrid polymer system. This composite approach integrates the mechanical properties of polyurethane with the low-surface-energy characteristics of fluorinated groups, achieving both structural integrity and reduced particle sticking that lowers substrate defects
2Object-affected harmful factors
If polishing pad with fluorinated repeating unit is used, then the number of defects is reduced to 40 or less, but the manufacturing complexity increases
Solution Approach 1:
The patent incorporates fluorinated repeating units directly into the polymer backbone during the polyurethane synthesis stage, rather than applying fluorinated coatings afterward. This preliminary integration of functional groups into the base polymer structure eliminates subsequent coating steps and simplifies manufacturing while maintaining the defect-reducing properties
Solution Approach 2:
The patent adjusts the molecular structure parameters of the polyurethane by incorporating specific fluorinated repeating units with controlled ratios (where n and m are integers from 0 to 20, not simultaneously 0). This parameter optimization achieves the desired surface properties for reduced particle adhesion while maintaining manufacturability through standard polymerization processes
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 significantly reduces the number of defects on substrates by 80% or more while maintaining or improving removal rates and cutting rates compared to conventional pads, ensuring high polishing quality and efficiency.
Implementation Method 1
the polyurethane includes a fluorinated repeating unit represented by Formula 1... wherein at least one of R11 and R12 is fluorine, and at least one of R13 and R14 is fluorine
Implementation Method 2
the foamed body may have an average pore size of 10 to 30 μm
Implementation Method 3
A difference of a contact angle of the polishing pad for pure water and a contact angle of the polishing pad for a fumed silica slurry may be 1.5 to 5
Data Source
AI summary
A polishing pad includes a polyurethane, wherein the polyurethane includes a fluorinated repeating unit represented by Formula 1, wherein the number of defects on a substrate after polishing with the polishing pad and a fumed silica slurry is 40 or less;wherein R11 and R12 are each independently selected from the group consisting of hydrogen, C1-C10 alkyl groups, and fluorine, with the proviso that at least one of R11 and R12 is fluorine, L is a C1-C5 alkylene group or —O—, R13 and R14 are each independently selected from the group consisting of hydrogen, C1-C10 alkyl groups, and fluorine, with the proviso that at least one of R13 and R14 is fluorine, and n and m are each independently an integer from 0 to 20, with the proviso that n and m are not simultaneously 0.