Semiconductor thin film, method and apparatus for producing the same, and semiconductor device and method of producing the same

In a polycrystalline silicon thin film transistor, a semiconductor device having a high field effect mobility is achieved by increasing a grain size of a silicon thin film. First, an insulation layer having a two-layer structure is formed on a transparent insulated substrate 201. In the insulation layer, a lower insulation layer 202, which is in contact with the transparent insulating substrate 201, is made to have a higher thermal conductivity than an upper insulation layer 203. Thereafter, the upper insulation layer 203. is patterned so that a plurality of stripes are formed thereon. Subsequently, an amorphous silicon thin film 204 is formed on the patterned insulation layer, and the insulation layer is irradiated with a laser light scanning in a direction parallel to the stripe pattern on the upper insulation layer 203. Thus, the amorphous silicon thin film 203 is formed into a polycrystalline silicon thin film 210.