A plasma processor processing a workpiece includes sources having
frequencies 2 MHz, 27 MHz, and 60 MHz, applied by three matching networks
to an electrode in a vacuum chamber including the workpiece.
Alternatively 60 MHz is applied to a second electrode by a fourth
matching network. The matching networks, substantially tuned to the
frequencies of the sources driving them, include series inductances so
the 2 MHz inductance exceeds the 27 MHz network inductance, and the 27
MHz network inductance exceeds the inductances of the 60 MHz networks.
The matching networks attenuate by at least 26 DB the frequencies of the
sources that do not drive them. Shunt inductors between the 27 and 60 MHz
sources decouple 2 MHz from the 27 and 60 MHz sources. A series resonant
circuit (resonant to about 5 MHz) shunts the 2 MHz network and the
electrode to help match the 2 MHz source to the electrode.