Oxygen and iodine-containing hydrofluorocarbon compound for etching semiconductor structures

A method comprises: introducing a vapor of an oxygen and iodine-containing etching compound into a chamber that contains a substrate having a silicon-containing film deposited thereon and a patterned mask layer deposited on the silicon-containing layer, wherein the oxygen and iodine-containing etching compound has the formula CnHxFyIzOe, wherein 0≤n≤10, 0≤x≤21, 0≤y≤21, 1≤z≤4 and 1≤e≤2; activating a plasma to produce an activated oxygen and iodine-containing etching compound; and allowing an etching reaction to proceed between the activated oxygen and iodine-containing etching compound and the silicon-containing film to selectively etch the silicon-containing film from the patterned mask layer, thereby forming a patterned structure.