Abstract: Provided is a plasma processing apparatus and method which has a plasma generating chamber into which gas is introduced and microwaves are transmitted, thereby generating plasma. The plasma is introduced into a processing chamber, in which a semiconductor substrate to be processed resides. An RF generator and DC generator are mixed together and are synchronized with the microwaves, such that they are applied to the substrate at the same times the microwaves act upon the gas to form plasma. Thus, variance of the DC bias and RF bias can be independently controlled, and damage to the substrate is reduced. In another embodiment, an RF bias voltage modulation circuit is used to shape the RF waveform in accordance with predetermined patterns.