Method for selectively scaling a field emission electron gun and device formed thereby

摘要

The present invention is directed to a method for selectively scaling the dimensions of a field emission electron gun. The electron gun includes a field emission tip followed by a dual electrode immersion lens. The lens consists of two planar electrodes separated by a dielectric layer. A well defined circular hole is present at the center of each electrode and the dielectric layer. A high scaling factor is applied to the region consisting of the first electrode and the emission tip, reducing the first electrode thickness and bore diameter and the distance between the tip and first electrode to the micrometer range. A weaker scaling factor is applied to the bore diameter of the second electrode and the spacing between the electrodes such that the second electrode bore diameter and distance between the electrodes are approximately equal and are greater than the first electrode thickness and bore diameter and the distance between the tip and first electrode.