The removal characteristics of polymer layers formed during the reactive ion etching of via holes with via etch- stopped on a TiN layer (VEST) structure were investigated under various ashing and stripping conditions. A relatively thick sidewall polymer layer containing large amounts of F and Ti due to the reaction between CFx- based etching gas and a sputtered Ti layer were observed, while a comparatively thin polymer layer with negligible F and only a small amount of Ti was formed at the bottom of the via hole. The intruded sunflower- shaped thick polymer layer at the boundary of the via hole was clearly distinguishable after ashing under various conditions. Oxygen- based plasma ashing removed F- containing carbon contaminants but left the metallorganic polymer due to the formation of metal oxides such as TiOx. Additional wet stripping is required to completely remove the metallorganic polymer residues. Nonhydroxylamine (non- HA)- based strippers more effectively removed the polymer layer than HA- based strippers, regardless of the photoresist used. Polymer hardening due to the ashing at elevated temperatures reduced the wet stripping capability. This study shows that a polymer- free via hole can be achieved by using a non- HA- based stripper and Ar dry cleaning and by keeping the ashing temperature low enough to prevent polymer hardening. (C) 2004 The Electrochemical Society.