Experiments With Dipole and Monopole Lenses for an SEM

University Of Chicago, Chicago IL

Investigators

Abstract

An Instrument development grant has been awarded to Albert Crewe of the University of Chicago to complete, test, and demonstrate a new and original scanning electron microscope (SEM), using a novel lens system, whose expected performance characteristics far exceed those of existing instruments. It is a dedicated low voltage, high resolution instrument that incorporates a permanent magnet lens, placed below the specimen. Such lenses have not been used previously but they show promise of permitting a considerable increase in resolution. The special value of these lenses are that they allow the use of very small focal lengths with correspondingly low aberrations. This makes it especially valuable for use with low accelerating voltages, although the lenses are not limited to this area. A second advantage is that simplified and more versatile column designs are allowed due to the post-specimen lens location. A third advantage is that the anticipated cost of the entire instrument, if made commercially, should be about half that of current high resolution scanning electron microscopes. Finally, the shape of the lens makes it easy to provide a large tilt angle for the specimen. The project involves the training of a number of students who will gain invaluable instrument design and development experience.