CMP Polishing Pad Polyurethane Formulation for Planarization
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Solution Overview
Problem
Current CMP polishing pads face a performance tradeoff between planarization efficiency and defectivity, with higher removal rates often resulting in increased defects, and existing methods struggle to achieve a balance between tensile modulus and elongation-to-break for improved bulk mechanical properties.
Innovation Solution
A solvent-free, two-component formulation comprising a liquid aromatic isocyanate component and a polyol component with a polyether backbone, combined with a curative, to form a polyurethane reaction product with a high tensile modulus and acceptable elongation, allowing for improved CMP polishing pad performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional casting or rapid injection molding methods are used with isocyanate-terminated urethane prepolymers, then the mold can be filled before viscosity builds too high, but the isocyanate content is limited and tensile modulus remains insufficient
Solution Approach 1:
The patent changes the chemical composition parameters by using aromatic diisocyanate with 15-40 wt% NCO content instead of traditional isocyanate-terminated prepolymers, and combines it with polyfunctional polyols (5-7 hydroxyl groups) to achieve both processability and high tensile modulus (≥200 MPa)
Solution Approach 2:
The patent creates a composite polyurethane system by reacting aromatic diisocyanate with polyfunctional polyols containing 5-7 hydroxyl groups, forming a crosslinked network structure that simultaneously provides mold filling capability and high tensile modulus
2Strength
If higher isocyanate content is used to improve tensile modulus, then planarization efficiency improves, but elongation-to-break decreases
Solution Approach 1:
The patent optimizes the stoichiometric ratio of NCO to OH groups and uses polyfunctional polyols with 5-7 hydroxyl groups to create a balanced crosslinked structure that achieves tensile modulus ≥200 MPa while maintaining elongation-to-break ≥100%
Solution Approach 2:
The patent forms a crosslinked polyurethane network by reacting aromatic diisocyanate with polyfunctional polyols, creating a composite structure that provides both high tensile modulus and acceptable elongation properties
3Productivity
If higher removal rate is achieved in CMP process, then planarization efficiency improves, but defectivity increases
Solution Approach 1:
The patent modifies the polyurethane formulation by using aromatic diisocyanate with specific NCO content (15-40 wt%) and polyfunctional polyols (5-7 OH groups) to achieve optimal mechanical properties that enable high removal rate while controlling defectivity
Solution Approach 2:
The patent creates local density variations through the crosslinked polyurethane structure formed by aromatic diisocyanate and polyfunctional polyols, providing appropriate hardness and compliance for defect-free polishing while maintaining high removal rate
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 achieves a tensile modulus of at least 200 MPa with elongation at break of over 100%, enhancing both mechanical strength and flexibility, thereby improving planarization efficiency while reducing defectivity.
Implementation Method 1
A solvent-free, two-component formulation comprising a liquid aromatic isocyanate component and a polyol component with a polyether backbone, combined with a curative, to form a polyurethane reaction product
Data Source
AI summary
A two component composition for making chemical mechanical polishing pad for polishing a semiconductor substrate is provided comprising a liquid aromatic isocyanate component having an unreacted isocyanate (NCO) concentration of from 15 to 40 wt. %, based on the total solids weight of the aromatic isocyanate component, such as methylene di(phenylisocyanate) (MDI), a liquid polyol component of a polyol having a polyether backbone and having from 5 to 7 hydroxyl groups per molecule, and a curative of one or more polyamine or diamine, wherein the reaction mixture comprises 50 to 65 wt. % of hard segment materials, based on the total weight of the reaction mixture. The composition when mixed cured to form a polyurethane reaction product. Also provided are CMP polishing pads made from the polyurethane reaction product by spraying the composition into a mold.