Microchemical Analysis in the SEM

Abstract

In most cases, it is desirable to obtain chemical information from specimens that are examined in the SEM. This is usually accomplished using energy dispersive x-ray spectrometry (EDS) or wavelength dispersive x-ray spectroscopy (WDS) technique. The microchemical analysis is accomplished by EDS detector or WDS spectrometer fitted in the column of the SEM. Integration of this detector or spectrometer with the SEM enables a user to determine the localized chemistry of a region. For example, the microchemical make-up of features that are only a few microns in size can be determined with a high degree of sensitivity. Not only the elements that make up a phase are detected (qualitative analysis) but also their concentrations are determined (quantitative analysis). The microchemical analysis is efficient and nondestructive and thus plays an important role in materials verification and phase identification. The EDS detector and WDS spectrometer are incorporated into the SEM in a way that does not disturb or affect the imaging capability of the instrument. The EDS and WDS identify the quantum characteristic x-ray energy and wavelength, respectively for elemental analysis. Their mode of operation is controlled by computers. This chapter describes the techniques used to undertake microchemical analysis in the SEM.