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.