JPS6415767A - Electric discharge device - Google Patents

Abstract

PURPOSE:To improve the durability of a device by changing the quality of a 2nd inorg. dielectric film thereby forming a prescribed 3-layered structure at the time of covering two electrodes on a 1st dielectric material with the 2nd dielectric material, forming the 3rd electrode thereon and covering the same with the 3rd dielectric material. CONSTITUTION:The Cr electrodes 4, 5 on an Al2O3 substrate 2 is coated with Al2O5 ceramics 3 and the electrode 6 consisting of Ti, W, etc., having high resistance to corrosion and oxidation is provided thereon. The Al2O3 layer 3 is formed into the 3-layered structure. The inside layer 31 is first formed to 0.3mum thickness at 50Angstrom /min, the intermediate 32 to 9mum thickness at about 750Angstrom /min and the outside layer 33 to 0.7mum thickness at about 50Angstrom /min, by which the film 31 having high adhesion, the film 32 allowing easy film formation and the dense film 33 having the high discharge resistance are obtd. A corrosion preventive function is improved and the destaticization and electrostatic charge uniform and stable over a long period of time are enabled according to this constitution. The performance of the device is improved as well.