Recessive self-aligned double patterning with gap-fill technology

In this paper, a recessive self-aligned double patterning (RSADP) process enabled by gap-fill technology is proposed and developed for BEOL applications. FEOL application is also possible by adding gap-fill/CMP steps to reverse the tone of contact/trench patterns. Compared with positive-tone spacer self-aligned double patterning (SADP), RSADP technique can reduce the process complexity by using less masks to pattern 2-D features. With a RSADP process, we successfully demonstrate (half-pitch) 50nm contact and 30nm line/space patterns using dry lithography.