Methods for etching a material layer for semiconductor applications

Embodiments of the present disclosure provide an apparatus and methods for etching a material layer with a cyclic etching and deposition process. In one embodiment, a method for etching a material layer on a substrate includes (a) etching at least a portion of a material layer on a substrate in an etch chamber to form an open feature having a bottom surface and sidewalls in the material layer, (b) forming a protection layer on the sidewalls and the bottom surface of the open feature from a protection layer gas mixture comprising at least one carbon-fluorine containing gas, (c) selectively removing the protection layer formed on the bottom surface of the open feature from a bottom surface open gas mixture comprising the carbon-fluorine containing gas, and (d)continuingly etching the material layer from the bottom surface of the open feature until a desired depth of the open feature is reached.