Patent ID: 11948771
Assignee: FEI COMPANY
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A method of determining an energy width of a charged particle beam, comprising the steps of:
providing a charged particle beam and directing said beam towards a specimen;
forming an energy-dispersed beam from a flux of charged particles transmitted through the specimen;
providing a slit element in a slit plane;
modifying said energy-dispersed beam to cause the energy-dispersed beam to have a defocus at the location of said slit plane, wherein the slit element does not cause said defocus and said step of modifying comprises:
forming a shadow part of said energy-dispersed beam by partially blocking said energy-dispersed beam with said slit element, and
forming an unblocked part of said energy-dispersed beam;

imaging said energy-dispersed beam, wherein the imaging comprises imaging at least part of said shadow part and said unblocked part of said energy-dispersed beam; and
determining an intensity gradient of said imaged energy-dispersed beam for determining said energy width.