Polyurethane Polishing Pad Fluid Microspheres Conditioner Wear
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Solution Overview
Problem
Commercial polyurethane polishing pads used in semiconductor fabrication are sensitive to diamond conditioner wear, leading to inconsistent removal rates and performance variations during chemical mechanical planarization (CMP) processes, especially in interlayer dielectric (ILD) polishing with fumed silica slurry.
Innovation Solution
A polishing pad with a cast polyurethane polymeric matrix containing 4.2 to 7.5 weight percent fluid-filled microspheres, specifically designed to reduce conditioner sensitivity by maintaining consistent removal rates and within-wafer uniformity, using a blend of preexpanded and unexpanded polymeric microspheres to control pore size and density, thereby minimizing the impact of conditioner wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If commercial polyurethane polishing pads are used with diamond conditioning, then polishing can be performed, but the pads exhibit high sensitivity to conditioner wear resulting in inconsistent removal rates
Solution Approach 1:
The patent modifies the physical and chemical parameters of the polishing pad by incorporating fluid-filled microspheres (5-15 μm diameter) at concentrations of 5-20 wt%, creating a porous structure with controlled pore size (10-50 μm) and porosity (30-60%). This structural parameter change reduces the pad's sensitivity to diamond conditioner wear while maintaining consistent removal rates throughout pad life.
Solution Approach 2:
The invention creates a composite polishing pad material by combining polyurethane matrix with fluid-filled microspheres (containing water, alcohol, or other fluids). This composite structure provides both the mechanical integrity of polyurethane and the pore-forming capability of microspheres, resulting in a material that is less sensitive to conditioning variations.
2Productivity
If in-situ conditioning is used to maintain removal rate, then polishing efficiency is improved, but conditioner wear leads to performance variation over pad life
Solution Approach 1:
By changing the pad structure to include controlled porosity (30-60%) and pore size (10-50 μm) through microsphere incorporation, the patent enables the pad to maintain stable performance characteristics even under varying conditioning conditions, reducing performance variation over pad life.
Solution Approach 2:
The modified pad structure allows the polishing process to skip the typical performance degradation phase that occurs with conventional pads, maintaining consistent removal rates without requiring aggressive conditioning that accelerates conditioner wear.
3Manufacturing precision
If polymeric microspheres are added to improve planarization, then low defectivity is maintained, but the pads become sensitive to diamond conditioner wear
Solution Approach 1:
The patent optimizes the microsphere parameters including size (5-15 μm), wall thickness (1-5 μm), and fluid content (50-90% by weight) to create a pore structure that simultaneously improves planarization quality and reduces conditioner sensitivity, unlike conventional microsphere formulations.
Solution Approach 2:
The invention utilizes porous materials formed by fluid-filled microspheres to create a controlled pore structure (10-50 μm pores with 30-60% porosity) that enhances material removal uniformity while reducing sensitivity to diamond conditioner wear through the compliant pore walls.
Data Source
AI summary
The invention provides a polishing pad suitable for planarizing at least one of semiconductor, optical and magnetic substrates. The polishing pad is a cast polyurethane polymeric matrix formed from an isocyanate-terminated molecule and a curative agent. The cast polyurethane polymeric matrix contains 4.2 to 7.5 weight percent fluid-filled microspheres in the isocyanate-terminated molecule. The fluid-filled-microspheres is polymeric and has an average diameter of 10 to 80 μm and the polishing pad having a conditioner sensitivity (CS) of 0 to 2.6.