Detection and Analysis of Low Energy Electrons in a Scanning Electron Microscope using a novel detector design based on the Bessel Box Energy Analyser

Advancements in the field of scanning electron microscopy have been one of the major nano technology enablers. A scanning electron microscope (SEM) generates a magnified image of the sample by bombarding it with an electron beam and detecting the electrons that scatter off the surface along with the electrons that are generated in the sample. In conventional SEMs, the generated or secondary electrons are detected by the famous Everhart Thornley detector via positively biased input-grid. However, in doing so, it loses energy and angular information of the electrons. This information is crucial to interpret the SEM image of the sample under study.
What is needed is a small and compact detector that can detect electrons and furnish energy information inside an SEM chamber. The detector designed to achieve these aims is able to detect low energy electrons at the same time able to take the geometrical constraints of the SEM into account. This study presents a design and implementation of a novel secondary electron detector based on the Bessel Box (BB) energy analyser for SEM
Simulations were carried out for the design in SIMION 8.1 ray tracing software. An energy resolution of 0.4% has been numerically calculated and experimentally tested in an ultra-high-vacuum chamber. This was followed by the integration of the BB detector to a conventional scanning electron microscope.
The device described would be appealing to the electron microscopy and spectroscopy at large. The detector has been successfully demonstrated for electron spectroscopy applications: Auger and secondary electron. It has also been demonstrated for secondary electron microscopy, all obtained by as-designed BB detector.