Secondary electron detection in the scanning electron microscope

A method of image simulation in the Scanning Electron Microscope (SEM) has been developed which takes into account image formation processes from the point of impact of the primary beam on the sample to the point of electron collection by the detector. Since the interactions of electrons within the sample have previously been reported in detail (M. Balasubramanyam et al., SPIE Proc. 2014 (1993) 104), this paper concentrates on the 3D simulation of the paths of the secondary electrons once they leave the sample surface. The computer modelling allows the collection characteristics of secondary electron detectors to be investigated, and examples of simulated images are shown. The techniques described can be used to improve the design of detectors for the SEM.