Apparatus and methods for simultaneously supporting multiple workpieces inside a processing space of a plasma processing system for simultaneous two-sided plasma processing. The apparatus may be a fixture having a carrier plate configured to be supported inside the processing space and a plurality of first openings extending through the thickness of the carrier plate. The carrier plate is configured to contact each of the workpieces over an annular region at an outer peripheral edge so that the first and second sides of each of the workpieces is exposed to the plasma through a respective one of said plurality of first openings.