In certain implementations, methods and apparatus include an antenna assembly having at least two overlapping and movable surface microwave plasma antennas. The antennas have respective pluralities of microwave transmissive openings formed therethrough. At least some of the openings of the respective antennas overlap with at least some of the openings of another antenna, and form an effective plurality of microwave transmissive openings through the antenna assembly. Microwave energy is passed through the effective plurality of openings of the antenna assembly and to a flowing gas effective to form a surface microwave plasma onto a substrate received within the processing chamber. At least one of the antennas is moved relative to another of the antennas to change at least one of size and shape of the effective plurality of openings through the antenna assembly effective to modify microwave energy passed through the antenna assembly to the substrate.
展开▼