CMP Polishing Pad Composition for Uniform Pore Distribution
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Solution Overview
Problem
Existing chemical mechanical polishing (CMP) pads exhibit variability in properties such as pore size distribution and specific gravity, leading to inconsistent polishing performance.
Innovation Solution
A polishing pad with a polishing layer formed by reacting an isocyanate-terminated pre-polymer with a blend of curatives in the presence of pre-expanded polymeric microspheres, resulting in a polymer matrix with controlled expansion and unimodal pore size distribution and low specific gravity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pre-expanded and un-expanded fluid-filled polymeric microspheres are used to create low specific gravity polishing pads, then the polishing pad achieves low specific gravity, but a bi-modal distribution of pores is created leading to variability in properties
Solution Approach 1:
The curative system is segmented into two distinct components: a polyamine curative and an amine curative. This segmentation allows each curative to perform a specific function - the polyamine curative initiates expansion while the amine curative controls the reaction rate, thereby achieving uniform unimodal pore distribution while maintaining low specific gravity.
Solution Approach 2:
The invention changes the chemical composition parameters of the curative system by introducing a specific blend of polyamine and amine curatives in controlled ratios. This parameter change enables precise control over the expansion process, transforming the pore size distribution from bi-modal to unimodal while preserving the low specific gravity characteristic.
2Quantity of substance
If polishing pads with low specific gravity are produced using fluid-filled polymeric microspheres, then the polishing pad achieves low specific gravity, but property variability increases
Solution Approach 1:
The dual-curative system creates a feedback mechanism where the polyamine curative's rapid expansion is moderated by the amine curative's slower reaction. This feedback control ensures consistent expansion behavior across all microspheres, reducing property variability and improving polishing performance reliability while maintaining low specific gravity.
3Quantity of substance
If unexpanded fluid-filled polymeric microspheres are used in the polishing layer, then the polishing pad achieves lower specific gravity, but the pore size distribution becomes bi-modal
Solution Approach 1:
The invention uses pre-expanded microspheres as the starting material rather than unexpanded ones. This preliminary expansion ensures all microspheres start at a consistent size and state, and the controlled curative blend then maintains this uniformity throughout the curing process, achieving both low specific gravity and unimodal pore distribution.
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 achieves consistent polishing performance with improved removal rates of metals and oxides, reducing specific gravity variability and enhancing polishing efficiency.
Implementation Method 1
a polymer matrix which is the reaction product of an isocyanate terminated oligomer or polymer, with a curative blend comprising two or more polyamine curatives
Implementation Method 2
pores are present in the polymer matrix, such pores being formed by expansion of pre-expanded fluid filled polymeric microspheres such expansion occurring during reaction
Data Source
AI summary
A polishing pad for chemical mechanical polishing comprises a polishing layer which comprises a polymer matrix which is the reaction product of an isocyanate terminated oligomer or polymer, with a curative blend comprising two or more polyamine curatives wherein pores are present in the polymer matrix, such pores being formed by expansion of pre-expanded fluid filled polymeric microspheres such expansion occurring during reaction of the isocyanate terminated oligomer or polymer with the two or more curatives, wherein the polishing layer is characterized by one or more of a ratio of shear loss modulus (G″) at 104° C. to shear loss modulus (G″) at 150° C. of at least 5:1; and a specific gravity of the polishing layer is less than or equal to 95% of a calculated specific gravity for the isocyanate terminated oligomer or polymer, the curative blend and the pre-expanded fluid filled polymeric microspheres.