Backscattered Electrons

Abstract

Close inspection of the trajectories in the Monte Carlo simulation of a flat, bulk target of gold at 0° tilt shown in Fig. 2.1 reveals that a significant fraction of the incident beam electrons undergo sufficient scattering events to completely reverse their initial direction of travel into the specimen, causing these electrons to return to the entrance surface and exit the specimen. These beam electrons that escape from the specimen are referred to as “backscattered electrons” (BSE) and constitute an important SEM imaging signal rich in information on specimen characteristics. The BSE signal can convey information on the specimen composition, topography, mass thickness, and crystallography. This module describes the properties of backscattered electrons and how those properties are modified by specimen characteristics to produce useful information in SEM images.