2020 年 63 巻 12 号 p. 623-628
Atomic layer etchings (ALE) with gas cluster ion beam (GCIB) were reviewed. Gas cluster ions are aggregates of thousands of atoms or molecules. Thus, energy/atom of gas cluster ions are easily reduced to several eV/atom. In addition, gas cluster ions realize transient high-temperature and high-pressure conditions on the bombard area, enhancement of chemical reaction and removal of chemically altered surface layer are expected. These irradiation effects are beneficial for ALE. In this report, ALE of metal films (Cu or Ni) by oxygen GCIB (O2-GCIB) with acetic acid or acetylacetone (acac) vapor were investigated. Metal oxide layer was removed owing to chemical reactions with acetic acid or acac included by 5 kV O2-GCIB irradiation. Since there was no physical sputtering by 5 kV O2-GCIB, etching terminated after removal of surface layer.