Detector optics for electron beam inspection system
US6777675B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 18, 2002 |
| Grant date | Aug 17, 2004 |
| Priority date | — |
| Expiry date | Apr 18, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/057
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electron beam column incorporating an asymmetrical detector optics assembly provides improved secondary electron collection. The electron beam column comprises an electron gun, an accelerating region, scanning deflectors, focusing lenses, secondary electron detectors and an asymmetrical detector optics assembly. The detector optics assembly comprises a field-free tube, asymmetrical with respect to the electron optical axis; the asymmetry can be introduced by offsetting the field-free tube from the electron optical axis or by chamfering the end of the tube. In other embodiments the detector optics assembly comprises a field-free tube and a voltage contrast plate, either or both of which are asymmetrical with respect to the electron optical axis.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.