Footing reduction of positive deep-UV photoresists on plasma-enhanced ARL (PE ARL) SiON substrates

Chemically-amplified positive DUV photoresists are well known to exhibit small profile deviation at the resist substrate interface, commonly called footing, when processed on substrates like silicon oxynitride (SiON), titanium nitride, and boron phosphorous silicate glass. Severe footing can cause etch problems resulting in critical dimension nonuniformity and degraded lithographic performance. The objective of this paper is to examine possible solutions to footing on SiON substrates by focusing on three main areas: photoresist formulation, photoresist processing and substrate manipulation.