Cu pattern etching by oxygen gas cluster ion beams with acetic acid vapor

Halogen free and low-temperature Cu etching was carried out using a gas cluster ion beam (GCIB) with acetic acid vapor. A very shallow Cu surface was oxidized by oxygen GCIB (O2-GCIB). Simultaneously, reactions between CuO and acetic acid occurred, and reaction products were desorbed by local heating of O₂-GCIB irradiation. Thus, Cu etching at a low-temperature (<;60 °C) was achieved. From cross-sectional images of Cu pattern with line width of 100 nm, anisotropic Cu etching was carried out with this technique.