Auger electron microscopy: an overview

The critical properties of scanning Auger microscopy are reviewed, such as could cause false information or imaging artefacts. Instrumental or data processing related effects appear in the case of beam current variation, of the background slope effect, and of the use of combined peak to background ratio. Another set of artefacts is mainly due to the significant differences between the penetration depth of the exciting primary electrons and the escape depth of the Auger electron signal. In this case the net effect is a surface elemental contrast which is dominated by the substrate or by the overlayer rather than by the surface under investigation. In addition, there are also topographical effects of the specimen under test which normally affect the Auger yield and hence the contrast in the image. Methods for the successful suppression of some of these artefacts are outlined. They are based on the creation of reference images from complementary signals acquired by additional detection channels in parallel with the Auger signal of interest. (author) 49 refs., 12 figs