Methods of determining aberrations of a charged particle beam, and charged particle beam system

Abstract

A method of determining aberrations of a charged particle beam () focused by a focusing lens () toward a sample () in a charged particle beam system is described. The method includes: (a) taking one or more images of the sample at one or more defocus settings to provide one or more taken images (h...); (b) simulating one or more images of the sample taken at the one or more defocus settings based on a set of beam aberration coefficients (C) and a focus image of the sample to provide one or more simulated images; (c) comparing the one or more taken images and the one or more simulated images for determining a magnitude (Ri) of a difference therebetween; and (d) varying the set of beam aberration coefficients (C) to provide an updated set of beam aberration coefficients (C) and repeating (b) and (c) using the updated set of beam aberration coefficients (C) in an iterative process for minimizing said magnitude (R). Alternatively, in (b), one or more beam cross sections may be simulated, and, in (c) the simulated beam cross sections may be compared with one or more retrieved beam cross sections retrieved from the one or more taken images for determining a magnitude (R) of a difference therebetween. Further, a charged particle beam system for imaging and/or inspecting a sample that is configured for any of such methods is provided.