Optical methods for the detection of atomic fluorine in plasma etch systems are discussed and an experimental comparison is made between detection by optical emission and by a novel method based on the chemiluminescence from solid silicon in the presence of atomic fluorine. Although both methods are, in principle, subject to interferences, they can readily be used for plasma etch process optimization and for end point detection.
Zijlstra, P. A., & Beenakker, C. I. M. (1981). Evaluation of silicon-chemiluminescence monitoring as a novel method for atomic fluorine determination and end point detection in plasma etch systems. Applied spectroscopy, 35(4), 413-417. https://doi.org/10.1366/0003702814732454