PHOTORESIST EROSION STUDIED IN AN INDUCTIVELY-COUPLED PLASMA REACTOR EMPLOYING CHF3

The evolution of integrated circuits into the ultralarge scale integra ted regime takes today's 0.35 mu m circuit design rules to even smalle r values of 0.18 mu m and beyond. As a consequence, photoresist masks are becoming thinner and even more prone to erosion by etching. For th is work an I-line novolak resist was used. Etch rates for various proc ess conditions using in situ ellipsometry were obtained. Also the fluo rocarbon surface layer, present on top of the photoresist during stead y state etching was examined with x-ray photoelectron spectroscopy. Th e investigated pressure range was 6 to 20 mTorr and the inductive powe r range was 300 to 1400 W. It was found that there are two distinct re gimes of etching behavior. At inductive powers below 600 W the etching is energy flux limited, at higher inductive powers the etching is ion energy limited. (C) 1998 American Vacuum Society.