Methods and apparatus provide plasma generation for semiconductor process chambers. In some embodiments, the plasma is generated by a system that may comprise a process chamber having at least two upper microwave cavities separated from a lower microwave cavity by a metallic plate with a plurality of radiation slots, at least one microwave input port connected to a first one of the at least two upper microwave cavities, at least two microwave input ports connected to a second one of the at least two upper microwave cavities, and the lower microwave cavity receives radiation through the plurality of radiation slots in the metallic plate from both of the at least two upper microwave cavities, the lower microwave cavity is configured to form an electric field that provides uniform plasma distribution in a process volume of the process chamber.