Modern developments in coatings characterization and microanalysis involving electron and ion beam applications

Abstract

Surface and thin film analysis can be accomplished by a growing array of increasingly sophisticated analysis techniques. Improvements in electron and ion sources have provided more localized analysis capabilities in Auger electron spectroscopy and secondary ion mass spectrometry (SIMS), and these features are described in this short review. In addition, improved ion sources have allowed more rapid and uniform depth profile analysis. Compact tandem ion accelerators have allowed the development of economical Rutherford backscattering spectrometers. Developments in analyzer design with small angular acceptance allow an alternative means of limiting the area of the specimen that is examined by X-ray photoelectron spectroscopy. Our understanding of the secondary ion yields in SIMS has improved slightly, which when combined with better calibration procedures makes a more quantitative technique. Rutherford backscattering spectroscopy has become increasingly popular as a means of quantitative surface and thin film analysis. These and other aspects of these techniques are described with accompanying illustrations and applications. Thin films analysis and the characterization of coatings, even thick coatings which can be efficiently stripped from a surface or extracted intact, can be examined not only by increasingly sophisticated scanning electron microscopy (SEM) and microanalysis but also by combinations of scanning and transmission electron microscopies, e.g. scanning transmission electron microscopy and analytical electron microscopy. These combined analytical approaches allow for corroboration in cases of certain ambiguity in composition or microstructure, and several examples of these techniques applied to thin film and coating characterization are illustrated. Examples include the use of conventional transmission electron microscopy, energy-dispersive X-ray microanalysis, electron energy loss spectrometry and SEM. Some specialized and novel techniques for thin film preparation are also described in this short overview which emphasizes the synergism of electron and ion microanalysis and the role that the thin specimen can play in the coating characterization. Morphological characterization is not treated in this overview.