Patent ID: 7453059

Claim:
A time-of-flight ion sensor for monitoring ion species in a plasma used for processing a substrate, the time-of-flight ion sensor comprising: a housing; a drift tube that is positioned in the housing the drift tube being configured as an energy analyzer; an extractor electrode positioned in the housing at a first end of the drift tube, the extractor electrode being configured to perform at least one of attraction and repulsion of ions from a plasma; a plurality of electrodes that are positioned at a first end of the drift tube proximate to the extractor electrode, the plurality of electrodes being biased so as to cause at least a portion of the attracted ions to enter the drift tube and to drift towards a second end of the drift tube; and an ion detector that is positioned proximate to the second end of the drift tube, the ion detector detecting arrival times associated with the at least a portion of the attracted ions.