The invention is directed to a countermeasure against a local amorphous region observed as an eddy pattern on a thermally crystallized crystalline silicon film. The local amorphous region is thought to result from a deficiently formed ultra-thin silicon oxide film by ozone water treatment, which causes a local phenomenon of repelling a catalyst element solution during spin coating. This inhibits a uniform addition of a catalyst element. A relationship between an ozone concentration of ozone water and a wait time between the ozone water treatment and the subsequent step of adding the catalyst element is deduced and used for planning the countermeasure against the local amorphous region.