Methods for etching a hardmask layer to transfer features into a material layer using an etch process are provided. The methods described herein advantageously facilitate profile and dimension control of features through a proper sidewall and bottom management scheme during the hardmask open process. In one embodiment, a method for etching a hardmask layer to form features in the hardmask layer includes supplying an etching gas mixture onto a substrate to etch an exposed portion of a hardmask layer exposed by a patterned photoresist layer disposed on the substrate, switching the etching gas mixture to a deposition gas mixture comprising a silicon containing gas to form a passivation layer on sidewalls of the hardmask layer and forming openings in the hardmask layer.