A processing method is described which has a first step of depositing on a substrate a specimen film which may be any one of a semiconductor, a metal and a insulator.In a second step, the surface of the specimen film deposited in the first step, is irradiated with an ion beam to produce a physical damage on the surface, next, in a third step, the damaged specimen film surface is selectively irradiated with the light to partially cause a photochemical reaction so that a mask pattern, which depends on the desired device structure, is formed on the film surface. Finally, in a fourth step, photoetching is performed using the mask pattern formed in the third step as a shielding member.