in the crystalline silicon film 206 constituting the first layer as is the case in the preferred embodiment 1 but impurities were not contained in the crystalline silicon film 207 constituting the second layer since the crystalline silicon film 206 constituting the first layer grew laterally in the crystalline silicon film 207 constituting the second layer also crystal growth reflecting the crystalline structure of the lower layer was observed this preferred embodiment is an example in which a crystalline silicon film formed utilizing the method of the present invention is used to obtain a tft an outline of the production process of the present preferred embodiment is shown in fig3 a to 3 f first a base silicon oxide film 302 was formed to a thickness of 2000 u00e5 on a substrate 301 then an amorphous silicon film was formed to a thickness of 500 u00e5 by plasma cvd after treating with hydrofluoric acid to remove a natural oxide film a thin oxide film was formed to a thickness of about 20 u00e5 by irradiation with uv rays in an oxygen atmosphere an acetate solution containing 10 ppm nickel was coated and held for 5 minutes after which spin drying has carried out using a spinner then heat was applied at 550 u00b0 c for 4 hours in a nitrogen atmosphere to crystallize the silicon film into a crystalline silicon film 303 fig3 a the nickel containing layer remaining on the crystalline silicon film 303 was then.