TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Properties: The inorganic polymer film has surface roughness (Ra) of 0.1-0.8 microns and maximum surface roughness (Rmax) of 3 microns or less. The inorganic polymer film has thickness of 0.6-40 microns. The stainless steel foil portion has thickness of 40-200 microns. Preferred Composition: The molar ratio of silicon (D nucleus) with respect to total amount of silicon comprised in the inorganic polymer film is 0.3 or more. The molar ratio of aluminum, titanium, zirconium, niobium, tantalum and/or tungsten with respect to silicon (Q nucleus) with respect to total amount of silicon comprised in the inorganic polymer film is 0.025-0.25.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Properties: The inorganic polymer film has surface roughness (Ra) of 0.1-0.8 microns and maximum surface roughness (Rmax) of 3 microns or less. The inorganic polymer film has thickness of 0.6-40 microns. The stainless steel foil portion has thickness of 40-200 microns. Preferred Composition: The molar ratio of silicon (D nucleus) with respect to total amount of silicon comprised in the inorganic polymer film is 0.3 or more. The molar ratio of aluminum, titanium, zirconium, niobium, tantalum and/or tungsten with respect to silicon (Q nucleus) with respect to total amount of silicon comprised in the inorganic polymer film is 0.025-0.25.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Group: The organic group bonded with silicon is methyl group. EXAMPLE - Ethyl acetoacetate (2 mol) and tetraethoxy titanate (1 mol) were dispersed in ethanol (20 mol). Polydimethyl siloxane (terminals modified with carbinol) having mean molecular weight of 3000 (0.5 mol) was added, and further mixed solution of ethanol (2 mol) and water (2 mol) was dripped. The obtained sol was applied on a substrate of thickness 100 microns, and dry-gelatinized at 150degreesC for 24 hours and heat processed at 200degreesC for 4 hours. A film having thickness of 2.5 microns, surface roughness (Ra) of 0.4 microns and maximum surface roughness (Rmax) of 1.5 microns was formed. The formed film had corrugated structure in its surface. Thus, a stainless steel foil portion covered with an insulation film having corrugated structure of submicron level was obtained. A thin film fine crystal silicon cell using the obtained stainless steel foil portion covered with an insulation film had high conversion efficiency.