Optical diagnostic techniques for low pressure plasmas and plasma processing.

Optical diagnostic techniques have greatly expanded our understanding of low pressure discharges used in etching and deposition processes for microelectronics devices. This paper reviews and compares the various techniques with particular emphasis on studies which are of relevance to low pressure plasma processing. Optical emission induced by electron-molecule collisions is reviewed, with emphasis on refinements of the technique to provide more quantitative information. Specifically, both space and time-resolved measurements, combined with high-resolution lineshape measurements and rare-gas actinometry have been shown to yield valuable information on radical and ion formation processes, ion motion, etc. Examples are also given where emission from products gives insights into etching mechanisms, and also serves as an in-situ measure of the etch rate.