Auger voltage contrast imaging for the delineation of two-dimensional junctions in cross-sectioned metal–oxide–semiconductor devices

A new two-dimensional junction delineation technique named Auger voltage contrast (AVC) is described. AVC is a mapping tool that indicates the dopant type of each point of the cross-sectioned surface by measuring the Auger electron energy shifts that mirror the workfunction differences caused by the built-in junction, i.e., caused by Fermi level differences between n- and p-doped silicon. AVC makes use of the dual capabilities of field emission Auger electron spectroscopy instrumentation for spectroscopy at each pixel and for high spatial resolution. A theoretical examination is made of the important practical aspects of this previously observed Auger energy line shift, in particular the effect of surface states on the Fermi level position and the effect of beam-induced electron-hole pair creation and transport. AVC results obtained from cross-sectioned metal–oxide–semiconductor structures are shown to have good agreement with both theory and with one-dimensional secondary ion mass spectroscopy and spread...