Multi-beam multi-column electron beam inspection system

Abstract

An electron optics assembly for a multi-column electron beam inspection tool comprises a single accelerator structure and a single focus electrode mounting plate for all columns; the other electron optical components are one per column and are independently alignable. The accelerator structure comprises first and final accelerator electrodes with a set of accelerator plates in between; the first and final accelerator plates have an aperture for each column and the accelerator plates have a single aperture such that the electron optical axes for all columns pass through the single aperture. Independently alignable focus electrodes are attached to the focus electrode mounting plate, allowing each electrode to be aligned to the electron optical axis of its corresponding column. There is one electron gun per column, mounted on the top of the single accelerator structure. In other embodiments, the electron guns are mounted to a single gun mounting plate positioned above the accelerator structure.

Dependencies are inferred from the claim text.