Effect of H2O2 Concentration and Slurry Dilution on Removal Rate and Surface Quality for a Cu Slurry

The effects of H2O2 concentration and slurry dilution on Cu removal rate and surface quality were investigated for a colloidal silica-based slurry. At 1:6 dilution, the Cu removal rate increased with increasing H2O2 concentration, reaching a maximum at 0.90 wt% (H2O2 threshold concentration), and then decreasing and leveling off at higher H2O2 concentrations. A smooth Cu surface was obtained above the H2O2 threshold, but a rough Cu surface was produced below the H2O2 threshold. At higher dilutions of 1:8 and 1:10, similar effects of H2O2 concentration on Cu removal rates and surface qualities were observed, but the H2O2 threshold shifted down to 0.74 and 0.66 %, respectively. Electrochemical measurements explain the observation of a rough Cu surface below the H2O2 threshold, and a smooth Cu surface above the H2O2 threshold.