Polyurethane Polishing Pad Uniform Cell Structure
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Solution Overview
Problem
Conventional polishing pads for silicon wafers face challenges in achieving uniform, fine cells for effective planarization, often requiring high amounts of solvents, leading to environmental concerns and increased costs, while also having issues with rigidity, cell uniformity, and dressing speed.
Innovation Solution
A manufacturing method involving the use of a silicone-based surfactant and aromatic polyamines with a melting point of 70°C or lower to produce polyurethane resin foams with uniform, fine cells, eliminating the need for halogen-based chain extenders and improving planarization characteristics and dressability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods using organic solvents or water are used to foam polyurethane, then the polymer can be foamed, but the cells obtained have a lower limit of average diameter of 100 μm and cannot achieve finer, uniform cells
Solution Approach 1:
The invention extracts and removes the fine particles (cell forming agents) from the polyurethane polymer after molding by immersing the molded intermediate in a solvent where the polymer is insoluble but the fine particles are soluble, thereby obtaining porous polyurethane resin with controlled cell structure
Solution Approach 2:
The invention changes the physical and chemical parameters of the system by selecting specific solvents with appropriate solubility characteristics - the solvent must dissolve the fine particles but not the polyurethane polymer, enabling selective removal of cell forming agents while maintaining polymer integrity
2Manufacturing precision
If solvent soluble fine particles are dispersed into polyurethane polymer and the molded intermediate is immersed in solvent to remove fine particles, then porous polyurethane resin can be formed, but a great quantity of solvent is required and treatment of solvent containing fine particle forming material is required which entails high cost
Solution Approach 1:
The invention discards the fine particles after they have served their purpose as cell forming agents by dissolving them in the solvent, while recovering and reusing the solvent for subsequent processing steps, thereby reducing overall solvent consumption and treatment costs
3Manufacturing precision
If fine-cavity foams are dispersed into polyurethane resin forming raw composition, then fine cells can be obtained, but fine-cavity foams have great tendency to float up in raw polyurethane reaction liquid due to density difference making uniform foam manufacturing difficult
Solution Approach 1:
The invention performs preliminary action by pre-forming the porous polyurethane resin structure before the foaming reaction occurs, dispersing fine particles into the polymer and creating the cell structure framework in advance, which prevents subsequent floating issues
4Manufacturing precision
If fine-cavity foams are used, then fine cells can be obtained, but fine-cavity foams are comparatively expensive and material of fine-cavity foams remains in foam product causing damage to cutting blade
Solution Approach 1:
The invention uses cheap, disposable fine particles as temporary cell forming agents that are easily dissolved and removed, replacing expensive fine-cavity foams. The fine particles serve their purpose during molding and are then discarded through solvent extraction, eliminating ongoing material costs and blade damage issues
5Manufacturing precision
If fine-cavity foams are used, then fine cells can be obtained, but fine cavity foams are easy to fly away requiring great cost in installing facilities for keeping working environment in good condition
Solution Approach 1:
The invention extracts and removes the fine particles after molding by dissolving them in solvent, eliminating the need to contain and control fine-cavity foam particles during processing, thereby reducing facility costs for working environment control
6Productivity
If conventional polishing pads are used, then polishing can be performed, but planarization characteristics are insufficient and dressing time is excessive
Solution Approach 1:
The invention changes the physical parameters of the polishing pad by controlling the cell size, distribution, and porosity of the polyurethane foam structure, optimizing these parameters to achieve better planarization characteristics and reduced dressing time
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 results in polishing pads with improved planarization characteristics, increased polishing speed, and reduced dressing time, enhancing the efficiency and environmental sustainability of semiconductor wafer fabrication.
Implementation Method 1
A manufacturing method involving the use of a silicone-based surfactant and aromatic polyamines with a melting point of 70°C or lower to produce polyurethane resin foams with uniform, fine cells
Implementation Method 2
aromatic polyamines with a melting point of 70°C or lower
Data Source
AI summary
A method for manufacturing a polishing pad made from a polyurethane resin foam having very uniform, fine cells therein and a polishing pad obtained by that method provides a polishing pad having better polishing characteristics (especially, in planarization) while providing improved dressability while maintaining the planarization characteristics and polishing speed of a conventional polishing pad. The polyurethane resin foam is a cured product obtained by reacting an isocyanate-terminated prepolymer with an aromatic polyamine chain extender having a melting point of 70° C. or lower, for example.