A Novel and Convenient Method for Monitoring Processing Plasma: The Insulated Pulse Probe Method

Abstract

The “insulated pulse probe method” is presented as a useful and convenient method suitable for monitoring plasmas for processing. This method is essentially stable against the change of the probe surface conditions and is free from the fatal problems particular to the conventional Langmuir probe method in reactive plasmas. In this method, the probe surface is originally covered with an insulating layer, and the time response of the probe current is measured on application of a square voltage pulse to the probe. The theoretical analysis on the response of the probe current is presented, and the electron temperature measured by this method in Ar plasma shows good agreement with that measured by the conventional Langmuir probe method. In addition, it is proposed that a silicon wafer under processing is usable as the probe to observe the plasma just in front of the wafer.