Patent attributes
A method of detecting non-uniformity in a plasma in a radio frequency plasma processing system, the method including generating a plasma within a reaction chamber of the radio frequency plasma processing system and detecting electrical signals from the plasma in a frequency range from a frequency of radio frequency power sustaining the plasma to a multiple of about ten times a frequency with a plurality of sensors disposed azimuthally about a chamber symmetry axis of the radio frequency plasma processing system. The method also including comparing the waveforms of the electrical signals picked up from the plasma by the plurality of sensors and determining when a plasma non-uniformity occurs based on the comparing the electrical property of the plasma detected by each of the plurality of sensors.
