CMP Polishing Pad with Fluid-Filled Microspheres for Conditioner Wear Resistance
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Solution Overview
Problem
Commercial polyurethane polishing pads for semiconductor fabrication are sensitive to diamond conditioner wear, leading to rapid deterioration in removal rate and performance variation during CMP processes, especially in interlayer dielectric polishing with fumed silica slurry.
Innovation Solution
A polishing pad manufacturing method involving a liquid polyurethane material with a blend of preexpanded and unexpanded fluid-filled polymeric microspheres, which are heated and cured to form a polyurethane matrix with reduced sensitivity to conditioner wear, maintaining high removal rates and within-wafer uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If commercial polyurethane polishing pads are used for CMP processes, then the pads provide mechanical integrity and chemical resistance, but the pads exhibit high sensitivity to diamond conditioner wear leading to rapid deterioration in removal rate
Solution Approach 1:
The patent modifies the physical and chemical parameters of the polishing pad by incorporating fluid-filled polymeric microspheres with specific size distributions (bimodal or multimodal) and controlling the liquid polyurethane material viscosity to specific ranges (100-10,000 cP). These parameter changes create a pad structure that maintains consistent removal rates by reducing sensitivity to conditioner wear through optimized pore structure and surface morphology.
Solution Approach 2:
The invention creates a composite polishing pad structure by combining liquid polyurethane material with fluid-filled polymeric microspheres. This composite formulation, containing 1-20 wt% microspheres, produces a pad with enhanced properties that reduce conditioner wear sensitivity while maintaining mechanical integrity and chemical resistance, effectively resolving the contradiction between reliability and harmful factor sensitivity.
2Productivity
If in-situ conditioning with diamond disks is applied to maintain removal rate, then the polishing surface is roughened to prevent glazing, but the removal rate varies as conditioning disk wears over pad life
Solution Approach 1:
The patent changes the surface properties and internal structure parameters of the polishing pad through controlled viscosity liquid polyurethane material (100-10,000 cP) and specific microsphere incorporation. These parameter changes create a pad that maintains more consistent removal rates during in-situ conditioning by reducing the impact of conditioning disk wear through optimized pore structure and surface morphology that facilitates more uniform material removal.
3Manufacturing precision
If polyurethane pads are manufactured by casting into cakes and cutting into thin polishing pads, then consistent reproducible polishing properties are achieved, but the pads remain sensitive to diamond conditioner wear
Solution Approach 1:
The invention enhances the conventional casting manufacturing approach by incorporating fluid-filled polymeric microspheres into the liquid polyurethane material before casting. This composite formulation (1-20 wt% microspheres) creates pads with improved conditioner wear resistance while maintaining the manufacturing precision and reproducible polishing properties achieved through the casting process, thus resolving the contradiction between manufacturing precision and reliability.
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 reduced sensitivity to conditioner wear, maintaining consistent high removal rates and within-wafer uniformity, improving the stability and efficiency of CMP processes.
Implementation Method 1
heating and curing the liquid polyurethane material and the blend of prexpanded and unexpanded fluid-filled polymeric microspheres to a temperature of at least Tstart of the unexpanded fluid-filled polymeric microspheres to increase the diameter of the unexpanded fluid-filled polymeric microspheres
Implementation Method 2
The liquid polyurethane material having a Tgel temperature... heating and curing the liquid polyurethane material... to a temperature of at least Tstart... and then solidify the liquid polyurethane material into a polyurethane matrix
Data Source
AI summary
The invention provides a method of manufacturing a polishing pad suitable for planarizing at least one of semiconductor, optical and magnetic substrates. The method obtains a liquid polyurethane material formed from an isocyanate-terminated molecule and a curative agent. The liquid polyurethane material contains 4.2 to 7.5 weight percent fluid-filled polymeric microspheres in the isocyanate-terminated molecule. The fluid-filled polymeric microspheres are a blend of preexpanded and unexpanded fluid-filled polymeric microspheres. The liquid polyurethane material contains a blend of preexpanded and unexpanded fluid-filled polymeric microspheres having a relative viscosityμμ0of 1.1 to 7. Then the liquid polyurethane material solidifies into a polyurethane matrix that contains preexpanded and expanded fluid-filled polymeric microsphere for forming the polishing pad.