Dual Damascene Etching Process Using Sacrificial Spin-on-Glass Film

Abstract

The dual damascene (DD) formation process for sub 0.2 µm feature size devices has been investigated. The via-first DD process, where via holes are first formed, followed by trench formation, used the antireflection film in via holes after the trench pattern lithography process. In subsequential trench etch process, crownlike etch residues of SiO2 were formed around via holes due to etch inhibiting effect of antireflection films in via holes. A spin-on-glass (SOG) film is filled in via holes as a sacrificial film before trench pattern lithography was used. It could eliminate the crownlike etch residues because of the absence of an antireflection film in via holes. Moreover, it could give via holes a rounded profile at their top edges. This DD process used for fabricating films with no etch residues and rounded via holes reduces the aspect ratio of via holes and was confirmed to be effective for subsequential metal filling process.