56nm-pitch low-k/Cu dual-damascene interconnects integration with sidewall image transfer (SIT) patterning scheme

Abstract

Three metal level 56nm-pitch Cu dual damascene interconnects in k2.7 low-k ILD have been demonstrated by using sidewall-image-transfer (SIT) patterning scheme to investigate the feasibility of the SIT process for sub 50nm-pitch technology node. 45nm-pitch line resistance (R) and capacitance (C) simulation are performed to estimate the R-C variation for double patterning schemes. The photoresist mandrel SIT process for 56nm-pitch Cu line is investigated to develop the constant line pitch and less line edge roughness (LER). The basic electrical properties such as line open/short and via chain open/short yields are ~100%. The 56nm-pitch R-C variation is comparable to simulated 80nm-pitch R-C variation. The SIT patterning process is a strong candidate to improve the R-C variation for sub50nm-pitch technology nodes.