a method of plasma assisted co 2 cleaning for dry removal of residual photoresist and sidewall polymer with an etch gas mixture comprising fluorine containing gas , oxygen and hydrogen in n 2 or h 2 o . the process removes polymer residues present on a metal layer on a substrate and on the sidewalls of metal lines and inhibits chlorine - based corrosion while being very selective to exposed ti , tin , al and sio 2 . the invention is particularly suited for removing post metal etch polymer residue from top and sidewall of metal lines .