Chemical Mechanical Planarization of Ruthenium with Oxone as Oxidizer

Abstract

Potassium peroxymonosulfate (Oxone) was investigated as an oxidizing agent in silica based slurries for chemical mechanical planarization of Ru. Upon addition of oxone, the Ru removal rate increases significantly in the pH range of 1‐6. The slurry stability is poor at pH 3 and higher. At pH 2, oxone enhances the Ru removal rate even in the absence of abrasive, indicating that a soft film is formed on the Ru surface. Ru dissolution experiments show that the static etch rate is low. The Ru removal rate variation with pressure and velocity does not follow the Preston equation.