Low voltage BSE imaging using FESEM

Backscattered electron (BSE) imaging is most commonly performed by applying accelerating voltages of 10kV and above to the specimen. For imaging of surface detail, the application of a lower accelerating voltage results in less beam penetration, spread and overall specimen damage. A field emission scanning electron microscope (FESEM) operated with high emission current (50μA) was used to increase the number of BSE obtainable from imaged specimens. When operated with a high condenser lens current and a lower accelerating voltage (<5kV) the interaction volume of the electron beam with the specimen was minimised. The lower voltage BSE images exhibited enhanced surface detail and contrast. Specimens that normally charged, locally affecting secondary electron (SE) detection, were imaged without such distortions when BSE were used. It was advantageous to use a range of applied accelerating voltages in order to provide the most image information.