Patent ID: 7922880

Claim:
An apparatus for processing material on a semiconductor wafer, comprising: (a) a process chamber having an inlet for introduction of an inert gas; (b) a wafer support for holding the wafer in position during processing of the material; (c) a first magnetic field source configured to generate a first magnetic field capable of shaping plasma in a first plasma region at a first elevation above the wafer support; (d) a second magnetic field source configured to generate a second magnetic field capable of shaping plasma in a second plasma region at a second elevation above the wafer support, wherein the second elevation is closer to the wafer support than the first elevation; and (f) an ion extractor positioned within the process chamber and configured to accept a positive DC bias, wherein the ion extractor is configured to increase plasma density and maintain the increased plasma density at the second elevation above the wafer support by transferring electrons generated in the first plasma region to the second plasma region, and wherein the ion extractor is configured to generate an electric field, wherein E vector, characterizing the electric field generated by the positively biased ion extractor crosses with the B vector generated by the second magnetic field source.