Patent ID: 7421974

Claim:
A plasma discharge apparatus comprising: a first electrode and a second electrode opposed to each other, a gas supplier to supply a reactive gas, and a power source to apply voltage across the first electrode and the second electrode at atmospheric pressure or approximately atmospheric pressure to induce a discharge, the reactive gas supplied by the gas supplier being changed into a reactive gas in a plasma state by the discharge and then a layer being formed by exposing a substrate to the reactive gas in a plasma state, wherein at least one of the first electrode and second electrode is a dielectric coated electrode which comprises a conductive base material and a dielectric layer which covers the conductive base material; the dielectric layer having a void volume of not more than 10% and a maximum surface roughness Rmax of not more than 10 μm; and being sealed with an inorganic compound which is hardened by a sol-gel reaction, the inorganic compound for the sealing after the sol-gel reaction containing not less than 60 mol % SiO x .