A method of manufacturing a polycrystalline silicon film having a particular field effect mobility is disclosed. A first polycrystalline silicon film is formed on a transparent insulation substrate. The surface of the silicon film is oxidized, and an amorphous silicon film is formed on the first polycrystalline silicon film and oxide layer. The amorphous silicon film is subjected to a solid phase growth process to be converted to a second polycrystalline silicon film. The field effect mobility of the second polycrystalline silicon film can be adjusted to a desired value by controlling the relative thicknesses of the first and second polycrystalline silicon films.