Effect of Hydrogen Peroxide on Oxidation of Copper in CMP Slurries Containing Glycine

Abstract

This study compares the oxidative dissolution, passivation, and polishing behavior of copper in chemical mechanical polishing (CMP) the presence of glycine when the potential was controlled electrochemically, and when the potential was controlled using hydrogen peroxide, the most common oxidizer used in commercial slurries. The dissolution behavior was investigated with the help of potential/pH diagrams for the copper-water-glycine and copper-water systems, potentiodynamic polarization measurements and weight loss experiments. In situ polarization measurements and polishing experiments were conducted to study the electrochemical behavior of copper during polishing. With electrochemical control, passivation was only observed at high pH. When peroxide was used as an oxidant, passivation was observed at neutral pH values, when the concentration exceeded relatively low threshold concentrations, suggesting the formation of a protective film. This phenomenon could have important utility for simultaneously achieving high selectivity and good planarization during copper CMP. © 2003 The Electrochemical Society. All rights reserved.