A simple hollow probe for monitoring ion-beam energy in processing plasmas

摘要

A simple hollow probe has been developed for monitoring ion-beam energy in various processing plasmas. The hollow probe consists of an insulated tube and a movable tungsten rod which is biased by a dc voltage. Two knees on the current-voltage characteristics of the hollow probe are detected when the ion beam injects in the hollow probe in a low-pressure double-plasma device. Its mechanism is also discussed by the Langmuir probe theory. It is found that the potential difference between the hollow-probe voltages corresponding to the two knees is in good agreement with the ion-beam energy measured by the conventional ion retarding energy analyzer. The spread angle of the ion beam in the double-plasma device is discussed with the hollow probe and the directional ion energy analyzer.