Auger Electron Spectroscopy (AES)
Auger Electron Spectroscopy (AES) is a surface analysis technique used to identify elements present within the top 50 angstroms of conductive and semi-conductive materials. AES is widely used by the electronics and metals industries, but is also a useful tool for many other industries requiring surface analysis, material characterization, and failure analysis. It is also useful for contaminant identification as contaminants or oxidation can greatly affect a sample’s electrical and chemical characteristics, its ability to be bonded, resistance to corrosive environments, and visual appearance.
AES provides elemental composition spectra for elements greater than He and concentrations above 0.1 to 1.0 atomic percent. The AES technique involves the bombardment of the sample with an energetic primary beam of electrons. This generates, among other things, a class of electrons known as auger electrons. The auger spectrum shows the peaks for the auger electron energy levels corresponding to the atoms from which the auger electrons were released. Since each element emits auger electrons with a distinct set of energies, the identity of the parent atom and hence the composition of the material can be determined.
AES can provide electron images, element line scans, element distribution maps, and depth profiles, in addition to element spectra of a sample’s surface. The depth profiles are obtained by argon ion sputter etching while monitoring the signal intensity of the selected elements. A graph is created showing the element signal intensity or concentration verses depth. This technique can be used for determining composition changes in layered samples and the approximate thickness of thin films.