In Situ Analysis of Fluorinated Gases in Plasma Etching by Infrared Spectroscopy

Abstract
Infrared absorption spectroscopy proves to be a useful tool in the evaluation of plasma chemical conversions of etch gas mixtures during plasma etching for microelectronics. The partial pressures of the various perfluorinated gas components are obtained from infrared spectra with sufficient accuracy and may yield information about the actual state of the system. Methods of spectra recording and partial pressure computation are discussed. To demonstrate the applicability of the method, the conversions of CF4 + O2, and C2F4 in a glow discharge are investigated.