A monomolecularfilm which can be used as a dielectric film is obtained on a substrate surface. For example, an aluminum foil electrode substrate having a natural oxide film is obtained by chemically adsorbing a chlorosilane-based surface active material comprising a fluorocarbon chain to the substrate. It is possible in this invention to have a pre-treatment as follows in lieu of using the natural oxide layer: forming an electrolytic oxidated layer by electrolytic oxidation of the metallic film, or bonding a thin oxide layer such as SiO.sub.2, Al.sub.2 O.sub.3 being several hundred nanometers in thickness to the surface metallic film by spatter deposition, thus obtaining an excellent capacitor. A capacitor can be obtained by deposition of the aluminum layer on the surface bilayer laminated film. A thin film capacitor which has a high volume can be obtained comprising a thin (nanometer level), substantially pinhole-free dielectric film by using a siloxane-based monomolecular film having a fluorocarbon chain as the dielectric film.