The crystallization method by laser light irradiation forms a multiplicity of convexes (ridges) in the surface of an obtained crystalline semiconductor film, deteriorating film quality. Therefore, it is a problem to provide a method for forming a ridge-reduced semiconductor film and a semiconductor device using such a semiconductor film. The present invention is characterized by heating a semiconductor film due to a heat processing method (RTA method: Rapid Thermal Anneal method) to irradiate light emitted from a lamp light source after crystallizing the semiconductor film by laser light, thereby reducing the ridge.