DUV RESIST ETCH SELECTIVITY IMPROVEMENTS USING UV STABILIZATION

The transition from i-line to DW (248 nm) processing requires lithogra phy and plasma engineers to address the issue of pattern transfer. The issue of the etch selectivity of DUV photoresists being lower than no volak based i-line photoresists becomes critical at hole and metal lev els. Here the selectivity of resist to the substrate are on the order of two or three to one. The traditional approach of just increasing th e resist thickness does not become an option as aspect ratios can incr ease to more than 3.5 for the resist process. A combination of improvi ng the etch selectivity and implementing a stabilization process with DUV resists allows the use of thinner resists. We demonstrate improvem ents in etch selectivity at the contact level using UV/Bake(TM) stabil ization of the resist films.