Chemical mechanical planarization (CMP) of silicon dioxide films was performed using mixed abrasive slurries (MASs) achieved by mixing in situ polymer and inorganic particles. The results were discussed in terms of material removal rate (MRR) and defectivity. We compared 30 nm silica colloids and 14 nm primary size ceria particles. Our experiments shed some light on the importance of the bond between polymer core and inorganic particles in the shell and on the differences between silica-based and ceria-based MASs. Although for the silica-based MAS the MRR passes through a maximum (17 nm/min for 2:3 ratio polymer:silica), for the ceria-based MAS it increases with the ceria solid content. The polymer:silica ratios used in the experiments spanned in the range from 1:15 to 10:1. (C) 2008 The Electrochemical Society.