Real-time Monitoring of Ion Energy and Ion Flux in Plasma Reactors Using RF Current and Voltage Measurements

摘要

A noninvasive, nonperturbing method for monitoring ion current and ion kinetic energy, suitable for use during actual processing in industrial plasma reactors, has been developed and validated. The method has been used to monitor the drift in ion current and ion energy that occurs in a radio frequency (rf) biased inductively coupled plasma reactor as a conductive layer slowly builds up on the dielectric window of the inductive source. Depending on experimental conditions, the deposited layer can have large effects on both ion current and ion energy. The observed drifts in ion energy are explained by three different types of mechanisms: bias voltage effects, sheath impedance effects, and ion transit time effects. These mechanisms, and the monitoring technique itself, are not limited to the particular experimental conditions of this study; rather, they apply to a wide range of plasmas and reactors.