A process for forming a fluoroalkyl acrylate polymer film on a substrate by plasma polymerization. The fluoroalkyl acrylate polymer film has a high sensitivity to high energy rays and an excellent resolving power, and is very useful as a resist film. The plasma polymerized film of the invention has little pinholes, and is endurable to dry etching. A patterned resist film is prepared by irradiating the film with high energy rays to form a latent pattern and developing the latent pattern by either a wet process using a solvent or an oxygen or oxygen-containing gas plasma etching. Also, a pattern can be formed in the film by only electron beam irradiation. The pattern formation can be attained by electron beam delineation without development treatment. The pattern formation by electron beam delineation is promoted by heat treating the delineated film at a temperature not less than the glass transition temperature of the polymer under reduced pressure or by treating the delineated film with hydrogen or an inert gas plasma.