A method for increasing etching selectivity of a developed silicon-containing photoresist layer on a non-silicon containing photoresist layer on a substrate. The developed silicon-containing photoresist layer includes polymer chains containing silicon. Next, the developed silicon-containing photoresist layer and uncovered portions of the non-silicon containing photoresist layer are exposed to an ultraviolet (UV) light, where the UV light emanates from a UV generating agent, such as neon, xenon, helium, hydrogen, or krypton gas in an inert gas (e.g., argon, etc.) plasma. A top portion of the developed silicon-containing photoresist layer is then converted to a hardened layer, where the hardened layer is created by cross-linking the polymer chains containing silicon and the cross-linking is activated by the UV light. Next, an etch is performed on the uncovered portions of the non-silicon containing photoresist layer and the substrate using the hardened layer.