Iodine-containing fluorocarbon and hydrofluorocarbon compounds for etching semiconductor structures

Disclosed are methods for etching a silicon-containing film to form a patterned structure, methods for reinforcing and/or strengthening and/or minimizing damage of a patterned mask layer while forming a patterned structure and methods for increasing etch resistance of a patterned mask layer in a process of forming a patterned structure. The methods include using an activated iodine-containing etching compound having the formula CnHxFyIz, wherein 4≤n≤10, 0≤x≤21, 0≤y≤21, and 1≤z≤4 as an etching gas. The activated iodine-containing etching compound produces iodine ions, which are implanted into the patterned hardmask layer, thereby strengthening the patterned mask layer.