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

Abstract

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