Abstract

Optical diagnostic techniques can provide unique insight into plasmas and the interaction of reactive plasmas with material surfaces. However, the application of these techniques to plasma processing is not straightforward and may present formidable difficulties even to experienced spectroscopists. One commonly used technique– optical emission spectroscopy (OES)–may provide misleading results due to strong spatial variations in a discharge and the dependence of OES signal intensity on the electron excitation rate. Other techniques such as laser-induced fluorescence (LIF) are often better suited for plasma diagnostics. Due to experimental requirements, however, this method is more difficult to implement and more limited in scope than OES. Variants of LIF, such as two-photon excitation and spinchange transitions, may be used to enhance the scope of LIF as a plasma diagnostic technique and thereby provide a greater understanding of material processing. Laser-initiated photoelectric emission may be used as an in situ optical probe of surfaces during plasma processing. The use of these techniques is reviewed and illustrated with recent applications.

© 1989 Optical Society of America