An ion uniformity monitoring device is positioned within a plasma process chamber and includes a plurality of sensors located above and a distance away from a workpiece within the chamber. The sensors are configured to detect the number of secondary electrons emitted from a surface of the workpiece exposed to a plasma process. Each sensor outputs a current signal proportional to the detected secondary electrons. A current comparator circuit outputs a processed signal resulting from each of the plurality of current signals. The detection of the secondary electrons emitted from the workpiece during plasma processing is indicative of the uniformity characteristic across the surface of the workpiece and may be performed in situ and during on-line plasma processing.
