Investigation of surface topography using a multidetector system in a SEM

Abstract

The backscattered electron (BSE) signal is widely used for examination of surface topography in a scanning electron microscope (SEM). For detection of this signal both the standard configuration of two detectors as well as a multidetector system are employed. In the BSE mode, the sum of signals becomes less dependent on the surface inclination whereas the difference signal becomes proportional to the local surface tilt angle. One can see, that the signal from the two-detector system is influenced by an artefact. A successful combination of several independent detector signals to improve the topographical image has been proposed. For an investigation of the topographic mode in SEM, six p–i–n diodes of small surface area were placed opposite to each other. The digital BSE signal processing system enabled realization of different algorithms of mixing signals coming from several detectors. Some ways for eliminating the artefacts were proposed. For example, a method to form images without a shadow effect was used. It is useful for distinguishing between artefacts and real features. Moreover, the experimental results indicate that the real topography of a specimen can be obtained if the specimen is rotated. The aim of this work was to use a multidetector system and to develop models to allow the data to be interpreted.