Magnetic axial field measurements on a high resolution miniature scanning electron microscope

Abstract

This article presents magnetic axial field measurements for a high resolution miniature scanning electron microscope (SEM). The experimental results correlate well with simulation predictions. The SEM has a total height of less than 55 mm. Based upon measured axial field distributions, the on-axis spherical and chromatic aberration coefficients for a 1 keV primary beam are predicted to be 0.36 and 0.6 mm, respectively, for a working distance of 7.5 mm. These aberrations are an order of magnitude smaller than those for conventional SEMs with comparable working distance conditions. The SEM design uses an in-specimen chamber permanent magnet objective lens that lies outside vacuum and can easily be replaced. © 2000 American Institute of Physics.