scanning low energy electron microscope, SLEEM

A "SLEEM (scanning low energy electron microscope)" is an instrument to form a surface image, in which the SLEEM image is obtained as follows. An incident electron beam with an energy of several 10 V to several 100 V is used. A small-sized focused electron probe is scanned over the surface of the specimen. Scattered electrons and secondary electrons from the specimen are detected by a SEM detector. To obtain surface information, the specimen area is kept at ultra high vacuum. The SLEEM instrument is usually made by modifying a SEM instrument, thus the beam scan system and secondary electron detector for the SEM instrument are used for the SLEEM instrument. Applying a negative voltage to the specimen gives rise to the formation of a cathode lens or a retarding electric field near the specimen. By varying the value of the negative voltage, the energy of the incident electron beam is varied. A high image resolution is attained at a low incident energy. The present SLEEM achieves a resolution of 10 nm at an incident energy of 10 eV.

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