Metrology and characterization of application specific chemical mechanical polishing pads

Abstract

There is a need for metrology, characterization, and optimization of chemical mechanical polishing (CMP) pad architecture before being put into service. A polishing pad which is made up of polyolefin material instead of conventional polyurethane has been developed. The surface of the pad has been modified to match the hardness of the surface of the material that is being polished. In this research, we coated the pad with tetraethylorthosilicate using plasma enhanced chemical vapor deposition for varying durations of time for optimum pad output. The pad was then extensively characterized using the several standard metrology techniques such as scanning electron microscopy, x-ray photoelectron spectroscopy, nanoindentation, etc. The CMP performance evaluation of all the candidate pads along with in situ measurement of dynamic coefficients of friction, material removal rate, and acoustic emission was done using CETR CP-4™ bench top CMP tester. There was a correlation and interdependence of the pad coating time and surface chemical, micromechanical, and tribological properties. However, their impact on the pad CMP performance was found to be indirect. Based upon these findings, suggestions were given for final pad architecture for commercialization. The demonstrated methodology can also be implemented for parametric optimization of novel polishing pads in the future.