CMP Pad with Non-Expandable Particles for Planarization
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Solution Overview
Problem
Conventional chemical mechanical polishing pads, especially porous ones, are ineffective in planarization due to excessive deformation and dishing during the polishing process, while non-porous pads face challenges in achieving uniform macrotexture and are difficult to machine without defects.
Innovation Solution
A chemical mechanical polishing pad comprising a polyurethane matrix with 1 to 20 wt% non-reactive, non-expandable polymer particles and less than 2 wt% expandable polymeric microspheres, which is conditioned and reconditioned to form a polishing layer with improved rigidity and macrotexture, minimizing substrate defects and dishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If porous polishing pads are used, then the pad can conform to variations in elevation of the substrate, but the pad deforms excessively under polishing pressure causing dishing and reduced planarization effectiveness
Solution Approach 1:
The patent changes the physical and chemical parameters of the polishing pad by incorporating non-expandable polymeric particles (1-20 wt%) and expandable polymeric microspheres (0.1-2 wt%) into the polishing layer matrix. This composition modification allows the pad to maintain rigidity while providing controlled conformity to substrate variations, resolving the contradiction between adaptability and planarization precision.
Solution Approach 2:
The polishing pad uses a composite structure combining a polymeric matrix with dispersed polymeric particles and microspheres. This composite material provides both the rigidity needed to prevent excessive deformation and the controlled compliance to conform to substrate topography, eliminating dishing while maintaining planarization effectiveness.
2Strength
If unfilled non-porous pads are used to improve rigidity, then the pad maintains structural integrity, but it becomes difficult to machine with desired macrotexture uniformity and produces rough edges and debris
Solution Approach 1:
The patent modifies the mechanical properties of the polishing pad by incorporating polymeric particles and microspheres, which change the material's machinability parameters. This allows the rigid non-porous pad to be machined with uniform macrotexture without producing rough edges and debris, resolving the contradiction between rigidity and ease of manufacture.
3Manufacturing precision
If porous pads with expandable polymeric microspheres are used, then microtexture is formed through wear, but the pad leads to dishing in the substrate
Solution Approach 1:
The patent extracts or removes the problematic expandable polymeric microspheres that cause excessive deformation and dishing, replacing them with non-expandable polymeric particles. This selective removal of the harmful component eliminates substrate dishing while retaining the ability to form microtexture through controlled wear of the polishing layer.
Solution Approach 2:
The patent changes the key parameter of particle expandability from 'expandable' to 'non-expandable', fundamentally altering the pad's deformation behavior under pressure. This parameter change eliminates the dishing effect while maintaining microtexture formation capabilities through the wear of the polishing layer.
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 provides enhanced planarization capabilities with reduced substrate defects and improved tungsten removal rates, maintaining effective macrotexture and machinability without excessive deformation or dishing.
Implementation Method 1
1 to 20 wt % based on total weight of the polishing layer of non-reactive, non-expandable polymeric particles dispersed in the polyurethane
Implementation Method 2
As the pad is conditioned by an abrasive material during patterned wafer polishing, wear of the polymer material exposes the pores to form microtexture
Implementation Method 3
A porous polishing pad 20, having pores 21 in a matrix polymer 22 can deform under the pressure of polishing
Implementation Method 4
The wafer surface is polished and made planar by chemical and mechanical action of the polishing layer and polishing medium on the surface
Data Source
AI summary
A method of polishing comprises providing a substrate to be planarized, providing a chemical mechanical polishing pad having a polishing layer comprising a polyurethane and 1 to 20 wt % based on total weight of the polishing layer of non-reactive, non-expandable polymeric particles dispersed in the polyurethane and less than 2 wt % expandable polymeric microspheres, conditioning the polishing layer to form a conditioned polishing layer, stopping the conditioning, polishing the substrate with the pad having the conditioned polishing layer, stopping the polishing, reconditioning the polishing layer to form a reconditioned polishing layer, stopping the reconditioning, and initiating additional polishing on the substrate or a second substrate.