Patent ID: 7789993

Claim:
A coil for use in a semiconductor processing system to generate a plasma with a magnetic field in a chamber, the coil comprising: a first coil segment having a first end and a second end, the first end of the first coil segment adapted to connect to a power source; a second coil segment having a first end and a second end; a third coil segment having a first end and a second end, the second end of the third coil segment adapted to connect to an external balance capacitor; a first internal balance capacitor connected in series between the second end of the first coil segment and the first end of the second coil segment; and a second internal balance capacitor connected in series between the second end of the second coil segment and the first end of the third coil segment; wherein the coil includes a plurality of turns around a vertical axis, and the first internal balance capacitor is adapted to provide a first voltage peak substantially aligned in a direction substantially parallel to the vertical axis with a first virtual ground along the third coil segment, the second internal balance capacitor is adapted to provide a second voltage peak substantially aligned in the direction substantially parallel to the vertical axis with a second virtual ground along the first coil segment, and the external balance capacitor is adapted to provide a third voltage peak substantially aligned in the direction substantially parallel to the vertical axis with a third virtual ground along the second coil segment.