TWI757849B

A plasma processing apparatus equipped with an electrode disposed inside a sample deck on which a wafer is mounted, the sample deck being disposed in the lower part within a processing chamber inside a vacuum container, the electrode being supplied with high frequency power during processing of the wafer, a ring-like member electrode made of a conductor disposed to surround the upper surface on the outer peripheral side of the sample deck, a first ring-like cover made of a dielectric body disposed to cover the ring-like member, and a second ring-like cover made of a conductor disposed to cover the first ring-like cover, and a controller that adjusts the magnitude of the high frequency power according to a result of detection of voltage of the high frequency power supplied to the ring-like member during processing of the wafer.