ELECTROSTATIC DEFLECTION SYSTEM WITH LOW ABERRATIONS AND VERTICAL BEAM INCIDENCE

摘要

Embodiments of the present invention may be utilized to improve electron beam deflection. One embodiment provides an electrostatic deflection system with electrodes that minimize aberrations and to achieve vertical incidence simultaneously. By using at least two stages of deflection for a deflection direction, the present invention allows the deflected electron beam to pass a back focal plane of an objective lens while deflection capacitors are not disposed across the back focal plane. As a result, deflection electrodes can have an angle of 120° to minimize aberrations and simultaneously achieve vertical incidence of the electron beam on a target to avoid distortions or changes in magnification with height variations of the target or focus variations.