Abstract:
To provide microwave excitation plasma processing device capable of generating wide-width plasma jet having high uniformity, high density, and low temperature even under intermediate pressure and high pressure. The microwave plasma processing device includes: dielectric substrate; tapered portion provided in one end portion of the dielectric substrate, the tapered portion being shaped so that thickness of the dielectric substrate becomes gradually smaller; microstrip line; ground conductor; microwave input portion; gas input port configured to input gas into the dielectric substrate; plasma generating portion; gas flow widening portion provided inside the dielectric substrate and configured to supply wide-width gas flow having uniform flow velocity to the plasma generating portion, the gas flow widening portion being formed to make a gas flow width wider as the gas flow advances; gas flow channel configured to supply the gas to the gas flow widening portion; and nozzle for blowing plasma.