The insulating layer 121 can be formed by using an inorganic insulating material such as silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, or aluminum oxynitride; acrylic acid; methacrylic acid; a derivative of the acrylic acid or the methacrylic acid; a heat-resistant high molecular weight material such as polyimide, aromatic polyamide, or polybenzimidazole; or