Autofocus method for a scanning electron microscope
US11380513B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 18, 2019 |
| Grant date | Jul 5, 2022 |
| Priority date | — |
| Expiry date | Jan 18, 2039 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/221
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The present invention relates to an autofocus technique for a scanning electron microscope using interlaced scan. The autofocus method for a scanning electron microscope, includes: generating a thinned image of a pattern (160) formed on a surface of a specimen by repeatedly scanning the specimen with an electron beam while shifting a scanning position of the electron beam by predetermined plural pixels in a direction perpendicular to a scanning direction; performing said generating a thinned image of the pattern (160) plural times, while changing a focal position and an irradiation position of the electron beam, to generate thinned images of the pattern (160); calculating a plurality of sharpness levels of the respective thinned images; and determining an optimum focal position based on the sharpness levels.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.