In this work, we investigated the adsorption characteristics of anionic polyelectrolytes, which are used in shallow trench isolation chemical mechanical polishing with ceria abrasives. Specifically, the adsorption isotherms and chain conformation of anionic polyelectrolytes were studied in order to elucidate the difference in removal rates of silicon dioxide (SiO2) and silicon nitride (Si3N4) layers and the high selectivity characteristics of ceria slurry. Adsorption isotherms, FT-IR spectroscopy and contact angle measurements revealed that the anionic polyelectrolyte additives had much better adsorption affinities for the Si3N4 surface than for the SiO2 surface. Moreover, blanket wafer polishing results were successfully correlated with the adsorption isotherms of polyelectrolytes on the oxide particle suspensions. (c) 2007 Elsevier Inc. All rights reserved.