Monitoring the Physicochemical Degradation of Polishing Pad Soaked in Hydrogen Peroxide during Chemical Mechanical Polishing

Abstract

The porous polyurethane polishing pads are extensively used in the chemical mechanical polishing. The pad property is very important and influences the polishing effectiveness and the wafer surface quality. Hence, in the present work, the physicochemical degradation of unused polyurethane polishing pads during metal chemical mechanical polishing (CMP) in the presence of hydrogen peroxide (H2O2) was studied. It was found that the polishing pads were reacted chemically with H2O2 resulting in degradation of the polymer chain network of polishing pad and reduction in the pad elastic modulus. Pad polymer network chain scission was observed during FT-IR evaluation confirming the degradation of the pad. CMP experiments with the H2O2 soaked pads resulted in change in material removal rate (MRR) and the within-wafer non-uniformity (WIWNU). Further Pad elastic modulus estimated by colorimetric evaluation and CIE Lab color coordinates. (C) 2018 The Electrochemical Society.