Combinations of point source electron beams and simple electrostatic lenses: Initial demonstrations of micron-scale lenses

Abstract

This paper presents results stemming from the incorporation of micron- and millimeter-scale electrostatic lenses into an electron projection microscope, wherein the lenses can be used to focus and otherwise influence electron beams emitted from electron point sources. Topics discussed include the impetus for adding lenses to a normally lensless microscope, details of the lens design and fabrication techniques (including two novel methods for making micron-scale lenses and apertures), descriptions of the test procedures and conditions, and the observed results and their possible implications. The advantage of using a millimeter-scale lens to increase the magnification of projected images is illustrated. Then the microfabrication of two-electrode lenses measuring 1 μm in diameter and 1.7 μm in length is described. Although less than ideal, one of these structures performed sufficiently well to create what may be the first electron beam focused by a truly micron-scale lens. The materials and construction procedures used to build lenses by hand with diameter of 20 μm and electrode spacings of 8 μm are described. Two-electrode lenses of this type have demonstrated the capacity to withstand applied biases of over 500 V, and to send an electron beam through crossover with relatively little distortion.