Potassium Bromate as an Oxidizing Agent in a Titania-Based Ru CMP Slurry

Abstract

Ru chemical mechanical planarization (CMP) was studied in slurries containing titania and potassium bromate at different pH values, showing that the Ru removal rate is enhanced at pH 2 or less. Potentiodynamic polarization studies indicate that the corrosion current is enhanced in the presence of bromate, while the static etch rate experiments show that the etch rate is low. Potassium bromate increases Ru removal only at anodic potentials or during mechanical abrasion. Studies at different concentrations of abrasive and oxidizing agent reveal that the removal rate enhancement saturates at 0.75 mM bromate and 4 wt % titania.