US Patent 8664594 Electron-optical system for high-speed and high-sensitivity inspections

The present disclosure provides an electron beam column with substantially improved resolution and/or throughput for inspecting manufactured substrates. The electron beam column comprises an electron gun, a scanner, an objective lens, and a detector. In accordance with one embodiment, the electron gun includes a gun lens having a flip-up pole piece configuration. In accordance with another embodiment, the scanner comprises a dual scanner having a pre-scanner and a main scanner, and the detector may be configured between the electron gun and the pre-scanner. In accordance with another embodiment, the electron beam column includes a continuously-variable aperture configured to select a beam current. Other embodiments relate to methods of using an electron beam column for automated inspection of manufactured substrates. In one embodiment, for example, an aperture size is adjusted to achieve a minimum spot size given a selected beam current and a column-condition domain being used.