Low energy selective etching of metal films in oxygen-containing high-density argon plasma

Abstract

The results of investigating the influence of the ion energy (E_i < 200 eV) on the etching of nanoscale Cu, Pt, Ta, and Ti films in an oxygen-containing high-density argon plasma of low-pressure (P < 0.4 Pa) inductive high-frequency (HF) discharges are presented. It is demonstrated that, in Ar plasma, the selective etching of metal films is achieved at ion energies close to the sputtering threshold. The selectivity of Cu, Pt, and Ta etching with respect to Ti etching increases sharply in Ar/O₂ plasma with a small (less than 5%) oxygen addition. Depending on the energy of incident Ar⁺ ions, the yields of Ta, Pt, and Cu sputtering in Ar plasma are in good agreement with semiempirical calculations.