Edge effects and image contrast in scanning Auger microscopy: A theory/experiment comparison

The contribution of surface roughness to the artefacts present in images and line‐scans from Scanning Auger Microscopes have been explored by Monte Carlo modelling and by experiment. The samples chosen for these studies are metal lines with sharp rectangular cross‐sections deposited upon silicon substrates. The Monte Carlo simulation reveals shadowing effects due to the analyser/sample geometry and the obstruction due to the height of the overlayer line; forward scattering effects through the sidewall of the overlayer which lead to edge enhancements in the overlayer and substrate Auger signals; back‐scattering effects which show up as an apparent broadening of the overlayer lines and substrate signal peaks appearing in the otherwise forbidden shadowed region. All of these effects are visible in the experimental results obtained for Si substrates with Al and with Au lines upon them. The experimental edge enhancement artefact is compared with the results of the simulation and good agreement is obtained. The difficulties which arise in the separation of topographical and chemical contrast are discussed and some suggestions for removal or reduction of the magnitude of these effects are outlined.