Image Number 13 for United States Patent #6825920.
A plasma processing system that comprises a process chamber, a plasma source, a light detection device and a controller. The controller is useful for determining a seasoning state of the plasma processing system. The present invention further provides a method of determining the seasoning state of a plasma processing system comprising the steps of forming a first plasma in the process chamber utilizing the plasma source; measuring a first signal related to light emitted from the first plasma using the light detection device and storing the first signal using the controller; forming a second plasma in the process chamber utilizing the plasma source; measuring a second signal related to light emitted from the second plasma using the light detection device and storing the second signal using the controller; and correlating a change between the first signal and the second signal with a seasoning state of the plasma processing system.
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