Chromatic monitoring for the processing of materials with plasmas

A non-invasive monitoring system for material-processing plasmas has been developed based on chromatic modulation. The monitor consists of two parts, one for monitoring the emission spectra of plasmas and the second for monitoring the thickness of films on semiconductors during etching or deposition. These chromatic systems offer significant speed advantages over equivalent spectroscopic techniques. Both systems have been tested on a variety of plasma chambers and typical results from both systems are presented. Chromatic monitoring provides rapid feedback on the state of a plasma and on film thickness, providing the possibility for real-time monitoring and control of the plasma state. Further enhancement of the chromatic technique allows two dimensional monitoring of the plasma, providing information on its uniformity