Nitric acid-based slurry with citric acid as an inhibitor for copper chemical mechanical polishing

A novel inhibitor, citric acid, was introduced in the HNO3-based slurry for copper chemical mechanical polishing. It was anticipated that a passivatio n layer could be formed on the copper surface in the presence of citric aci d. In a 3 vol.% HNO3 solution, the passivation effect derived from citric a cid saturated as the citric acid concentration reached ca. 0.01 M. The poli shing rate was found to decrease with the addition of citric acid. The resu lts showed that the HNO3-based slurry with citric acid as an inhibitor coul d achieve good surface planarity for copper chemical mechanical polishing. (C) 1999 Published by Elsevier Science S.A. All rights reserved.