A method for transferring a pattern through a photoresist layer in the fabrication of submicron semiconductor devices structures is disclosed. A photoresist is provided on a substrate and the same is imagewise exposed with a desired pattern to form exposed and unexposed patterned areas in the top surface of the photoresist. The photoresist is then baked to form cross-linked regions in the exposed pattern areas of the photoresist. Silylation is then performed to incorporate silicon into the unexposed patterned areas of the photoresist, wherein some incorporation of silicon occurs in the exposed patterned crosslinked areas of the photoresist. The patterned photoresist is subsequently etched using a high density, low pressure, anisotropic O.sub.2 plasma alone to produce residue-free images with vertical wall profiles in the photoresist. This method is particularly advantageous with RFI reactive ion etch systems.