Method for obtaining a scanning transmission image of a sample in a particle-optical apparatus
US7825378B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 20, 2008 |
| Grant date | Nov 2, 2010 |
| Priority date | — |
| Expiry date | Jul 17, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/2809
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method for improving the resolution of STEM images of thick samples. In STEM, the diameter of the cross-over depends on the opening half-angle α of the beam and can be as low as 0.1 nm. For optimum resolution an opening half-angle is chosen at which the diameter of the cross-over R(α) shows a minimum. For thick samples the resolution is, for those parts of the sample removed from the cross-over plane, limited by the convergence of the beam, resulting in a diameter D of the beam at the surface of the sample. The opening angle is chosen to balance the contribution of convergence and of diameter of the cross-over by choosing an opening half-angle smaller than the optimum opening half-angle. Effectively the sample is then scanned with a beam that has a substantially constant diameter over the length of the sample material through which the electrons have to travel.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.