Effects of Ceria Abrasives on the Chemical Mechanical Polishing of Molybdenum Film with Alkaline H2O2 Slurries

Abstract

The impact of ceria abrasives on the chemical mechanical polishing (CMP) of molybdenum (Mo) films was examined in alkaline slurries utilizing H2O2 as an oxidizer and ceria abrasives. The static etching rate (SER) decreased after the addition of ceria abrasives to the alkaline H2O2-based slurry, while the removal rate (RR) increased except for that of the slurry at pH 9. At pH 9, following the etching of the Mo film in an H2O2 solution with ceria, the surface became coated with MoO3 and Ce2Mo4O15 species. These species originated from the interaction between ceria, H2O2, and molybdic acid. The Ce2Mo4O15 particles envelop the MoO3 surface, thereby preventing the etching of loose MoO3 and hindering further oxidation of Mo to MoO3. This process effectively reduces the RR of Mo. Utilizing ceria slurries at appropriate pH values facilitates achieving a smooth surface with a reasonable RR.