For the layer 36 d of the first electrode, a material capable of preventing oxidation and corrosion of the layer 36 c of the first electrode and avoiding hillock or the like is preferred (typically a metal nitride such as TiN or WN), and the thickness of the layer is set to 20 to 100 nm. [0137] The layers 36 a to 36 d of the first electrode can be formed at the same time other wires, for example,