Beam interactions, resolution and contrast in the SEM.

Backscattered and secondary electrons are both used in the SEM for imaging purposes. The backscattered signal is the result of high angle elastic scattering events, while the secondary signal is the result of knock-on inelastic collisions. The characteristic differences between images in the two modes arise from the details of the relevant interactions in the two cases. In order to examine this in a quantitative manner Monte Carlo electron trajectory simulation techniques have been used.