Barriers to AEM: Contamination and Etching

Abstract

Contamination and etching are terms used quite negatively by the analytical electron microscopist. The mental “images” evoked are of a loss of resolution, a decrease in signal/noise ratio, destruction of the microstructure, etc. Yet more propitious results may be achieved by using our empirical understanding of the phenomena to manufacture microcircuits, measure foil thickness, or to preferentially etch microstructures. For the most part, however, the effects of rapid contamination buildup or the local loss in specimen mass are viewed as worse than annoying. They are, in fact, significant barriers to continued advances in true microchemical and high resolution microstructural analyses. The present chapter attempts to summarize our understanding of the physical processes contributing to each phenomenon, to illustrate their effects on AEM, to describe some working cures (and even a few applications), and to project some avenues for further improvement.