This work describes the comparison of experimental measurements of electron beam spread in the environmental scanning electron microscope with model predictions. Beam spreading is the result of primary electrons being scattered out of the focused beam by interaction with gas molecules in the low vacuum specimen chamber. The scattered electrons form a skirt of electrons around the central probe. The intensity of the skirt depends on the gas pressure in the chamber, beam-gas path length, beam voltage, and gas composition. A model has been independently developed which under a given set of conditions predicts the radial intensity of the beam skirt were made under controlled conditions for comparison with model predictions of beamskirting. The model predicts the trends observed in the experimentally determined scattering intensities however there does appear to be a systemmatic deviation from the measurements.
Issue: No. 5
Pub Type: Journals
beam spread, electron microscope, electron scattering, environmental SEM, ESEM Monte Carlo, model, simulation, skirt