The insulating film can be made from inorganic insulating material such as silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride and aluminum oxynitride; acrylic acid, mathacrylic acid or a derivative thereof; a heat-resistant polymer such as polyimide, aromatic polyimide and polybenzimidazole; an inorganic siloxane-based insulating material containing Si???O???Si bo