Scanning tunneling microscope microlens with magnetic focusing

We describe a design for a low‐energy scanning tunneling microscope microlens with magnetic focusing, to achieve several improvements over conventional lens systems and previously reported microlens systems. First, scaling of the lens dimensions yields corresponding scaling of spherical and chromatic aberration coefficients. Second, magnetic focusing avoids the difficulty inherent in electrostatic microlenses of withstanding large potential differences over short distances, which can lead to dielectric breakdown in insulating elements of the lens, although magnetic focusing has an analogous problem with maximum achievable fields. Third, a low‐energy (100–200 eV) electron beam offers a significant advantage in lithography, where proximity effect and scattering within the resist from conventional high‐energy (>1 keV) electron beam systems act as serious limitations on pattern fidelity. Calculations indicate that for reasonable values of lens parameters (aperture potential=60–200 V, Bz=1.4–2 T, tip radius=30...