Environmentally harmonized C F3 i plasma for low-damage and highly selective low- k etching

Low-damage, high-rate, and highly selective low- k etching can be simultaneously satisfied using a plasma with an environmentally harmonized gas chemistry (C F3 I). Such a C F3 I plasma can drastically reduce the irradiation damage by ultraviolet (UV) photons during low- k etching, because the intensity of UV in C F3 I plasma is much lower than that in conventional C F4 plasma. The etching selectivity of SiOCH to a photoresist can be drastically improved by using C F3 I plasma because of reducing F radical generation. In addition, pulse-time-modulated C F3 I plasma causes a drastic increase in the etching rate because a large amount of negative ions can be generated. These results show that C F3 I plasma is a very promising candidate for low-damage and highly selective low- k etching.