Patent attributes
Inductively coupled plasma (ICP) RF power delivery systems are disclosed that include at least two ICP coils. At least one of the ICP coils is directly driven by an RF resonant power amplifier that includes a resonant tank comprising the ICP coil. A controller is configured to control the power into the direct driven ICP coil by varying a corresponding DC voltage source and simultaneously varying operating frequency into the ICP coil by allowing a resonant voltage waveform across a corresponding open switch network to rise and then fall to substantially zero volts before closing the corresponding switch network for a remainder of an RF cycle. Some variations comprise at least one passive ICP coil that is arranged and configured to be inductively coupled to the first ICP coil, and the passive ICP coil is terminated by an independently adjustable impedance.
