A technique, where a semiconductor film having a crystal structure is obtained using a metal element that helps crystallization of the semiconductor film, then that metal element remained in the film is effectively removed, as a result variation among elements is reduced, is provided. In a process for forming a gettering site, a semiconductor film containing a rare-gas element is formed, then an anti-diffusion film for preventing diffusion of the rare-gas element is formed, thereby the metal element in another semiconductor film is effectively removed, particularly in a gettering that is a heating treatment at a high temperature of 600.degree. C. or more.