Plasma reactor

A plasma reactor includes: a process chamber, at the inner bottom of the process chamber being provided a base, the base being connected to a RF power source via a RF match network, wherein a to-be-processed wafer is held above the base, an upper electrode assembly is provided at the inner top of the process chamber, and a plasma processing space is arranged between the base and the upper electrode assembly; a first conductive ground ring surrounding the outer periphery of the base; a second conductive ground ring connected between the outer sidewall of the first conductive ground ring and the inner sidewall of the process chamber, a plurality of gas channels being provided on the second conductive ground ring such that gas in the plasma processing space can be exhausted through the plurality of gas channels; an insulating ring provided between the base and the first conductive ground ring, wherein dielectric constant of the insulating ring is less than 3.5.