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

Claim 10:
11. A transmission Charged Particle Microscope (CPM), comprising:
a specimen holder for holding a specimen;
a source for producing a beam of charged particles;
an illuminator for directing said beam on to said specimen;
an imaging system for receiving a flux of charged particles transmitted through the specimen and directing it onto a sensing device, wherein said imaging system comprise a Post-Column Filter (PCF), the PCF comprising:
an entrance plane;
an image plane;
a slit plane between said entrance plane and said image plane;
a dispersing device provided between said entrance plane and said slit plane for forming an energy-dispersed beam from the flux of charged particles transmitted through the specimen, said energy-dispersed beam having a defocus at the slit plane; and
a slit element at the location of said slit plane, the slit element being configured to modify said energy-dispersed beam at the location of said slit plane, wherein 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; and

a controller, for controlling at least some operational aspects of the CPM, the operational aspects including:
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 an energy width.