Slurry chemistries utilizing several simple oxy-anions are proposed to meet some of the requirements for low pressure chemical mechanical polishing of Ta barrier and Cu lines in nonalkaline dispersions. Polish rates (PRs) were measured for Cu and Ta disks using H2O2 based slurries containing anions of phosphate, sulfate, chlorate, carbonate, nitrate, or persulfate. Polishing of Cu, Ta, TaN, and SiO2 wafers using the sulfate-containing slurry demonstrated a high selectivity (similar to 15) of Ta: Cu PRs and could be controlled by varying the anion and/or the pH of the slurry. The processed wafers showed surface morphologies with acceptable roughness (<1 nm) and peak-to-valley distances (<10 nm). (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3418616] All rights reserved.