Study on rinse material for pattern collapse mitigation in EUV lithography

Extreme ultraviolet (EUV) lithography is part of the high-volume manufacturing (HVM) processes for devices beyond 7 nm node. However, the technology still has several issues for HVM. Especially, RLS (Resolution, LWR, and Sensitivity) trade-off remains as one of the obvious problems for EUV Lithography. In which, resist pattern collapse is one of the hurdles that is preventing a process window/margin for resist patterning. Resist, under-layer, and rinse materials are continuously being developed to mitigate resist pattern collapse. In such status, rinse materials for chemically amplified resist (CAR) in the development process are known well as one approach for mitigation of the pattern collapse. In this study, we focused on the effectiveness of rinse material against lithography performance with parameters, such as surface tension and affinity with resist. In the paper, Rinse material considering low surface tension and low affinity with resist exhibited significant pattern collapse mitigation and wide process window at 28nm pitch. In addition to the rinse study, a new rinse process was investigated focusing on resist surface modification for more pattern collapse mitigation than the conventional process by suppression of water droplet generation. Furthermore, New rinse process exhibited better pattern collapse margin than the conventional rinse process.