Abstract: In a laser assisted semiconductor etching process, a krypton fluoride excimer laser operating at 248 nm excites a carbonyl dichloride COCl.sub.2 radical precursor gas which decomposes into carbon monoxide and also atomic chlorine that bonds to laser illuminated surface layer materials of semiconductor devices to create gaseous chlorides which desorb to perfect selective etching, the surface layer material being Cu, Al, amphorous silicon, Ga.sub.(x) Al.sub.(1-x) As, CuIn.sub.(x) Ga.sub.(1-x) Se.sub.2, CdZnS, ZnO and other materials useful in the manufacture of semiconductor devices and solar cells.