Abstract: A microwave supply mechanism for supplying microwaves from a microwave-generating power supply part to a load, includes: a microwave transmission path having a coaxial structure and through which the microwaves from the microwave-generating power supply part are transmitted; an antenna provided at a tip of the microwave transmission path and configured to radiate the microwaves and supply the microwaves to the load; an impedance matching part provided in the microwave transmission path and configured to match impedance on a power supply side and impedance on a load side; and an output voltage adjustment part provided between the impedance matching part and the antenna and configured to adjust a microwave output voltage in the antenna by adjusting impedance.

Abstract: A plasma processing apparatus includes a planar antenna member, which introduces electromagnetic waves generated by means of an electromagnetic wave generator into a processing chamber; a waveguide which supplies the electromagnetic waves to the planar antenna member; and a wave retardation plate, which is provided on the planar antenna member, and changes the wavelength of the electromagnetic waves supplied from the waveguide; a cover member which covers the wave retardation plate and the planar antenna member from above. The wave retardation plate is configured using a dielectric material, and the permittivity of the region between the planar antenna member and the cover member is not uniform on the plane parallel to the upper surface of the planar antenna member.