Patent attributes
A system and method for using plasma to treat a substrate are described. The system includes a substrate holder disposed within a plasma processing system, and arranged to support a substrate, a first signal generator for coupling a first signal at a first frequency to plasma in the plasma processing system, and a second signal generator for coupling a second signal at a second frequency to plasma in the plasma processing system, wherein the second frequency being less than the first frequency. The system further includes an amplitude modulation circuit for modulating the first signal between a high amplitude state and a low amplitude state in response to an amplitude modulation signal, and a timing circuit configured to define the amplitude modulation signal that synchronizes the amplitude modulation of the first signal with a target phase for each cycle of the second signal.