Methods for etching a material layer for semiconductor applications

An apparatus and method for etching a material layer with a cyclic etching and deposition process. The method for etching a material layer on a substrate includes: (a) etching at least a portion of a material layer (302) on a substrate (101) in an etch chamber (100) to form an open feature (360) having a bottom surface (312) and sidewalls in the material layer (302); (b) forming a protection layer (314) on the sidewalls and the bottom surface (312) of the open feature (360) from a protection layer (314) gas mixture comprising at least one carbon-fluorine containing gas; (c) selectively removing the protection layer (314) formed on the bottom surface (312) of the open feature (360) from a bottom surface (312) open gas mixture comprising the carbon-fluorine containing gas; and (d) continuingly etching the material layer (302) from the bottom surface (312) of the open feature (360) until a desired depth of the open feature (360) is reached.