Abstract: In but one aspect of the invention, a plasma etching method includes forming polymer material over at least some internal surfaces of a dual powered plasma etch chamber while first plasma etching an outer surface of a semiconductor wafer received by a wafer holder within the chamber. After the first plasma etching, second plasma etching is conducted of polymer material from the chamber internal surfaces while providing a bias power at the wafer holder effective to produce an ac peak voltage at the wafer surface of greater than zero and less than 200 Volts. In one implementation, second plasma etching is conducted of polymer material from the chamber internal surfaces while providing a bias power at the wafer holder of greater than zero Watts and less or equal to about 1 Watt/cm2 of wafer surface area on one side.