Switchable matching network and an inductively coupled plasma processing apparatus having such network

An apparatus for supplying bias powers to cathode of a plasma processor, comprising:

• a first RF bias supply;
• a second RF bias supply;
• a switchable matching network, switchably coupling one of the first RF bias supply and the second RF bias supply to the cathode, the switchable matching network comprising:
• a first matching circuit having a first input port connected to the first RF bias supply and a first output port coupled to the cathode;
• a second matching circuit having a second input port connected to the second RF bias supply and a second output port coupled to the cathode;
• a variable capacitor having one terminal grounded;
• and
• a switching device, selectively connecting the variable capacitor directly to the first input port or directly to the second output port.

An inductive coupling plasma processor having a switchable bias, comprising:

• a vacuum chamber;
• a source RF supply;
• a first RF bias supply;
• a second RF bias supply;
• an inductive antenna coupled to the source RF supply;
• and
• cathode disposed inside the vacuum chamber and switchably coupled to the first RF bias supply and the second RF bias supply via a switchable matching network;
• the switchable matching network comprising:
• a first matching circuit having a first input port connected to the first RF bias supply and a first output port coupled to the cathode;
• a second matching circuit having a second input port connected to the second RF bias supply and a second output port coupled to the first output port;
• a variable capacitor having one terminal grounded;
• and
• a switching device selectively connecting the variable capacitor directly to the first input port or directly to the second output port.