An apparatus is provided for semiconductor wafer plasma processing. The apparatus includes a chamber having a lower electrode and an upper electrode disposed therein. The lower electrode is defined to transmit a radiofrequency current through the chamber to generate a plasma within the chamber. The lower electrode is also defined to support a semiconductor wafer in exposure to the plasma. The upper electrode is disposed above and in a spaced apart relationship with the lower electrode. The upper electrode is defined by a doped semiconductor material. A doping concentration within the upper electrode varies radially from a center to a periphery of the upper electrode. The electric potential of the upper electrode influences an electric potential of the plasma within the chamber.