Hostname: page-component-586b7cd67f-2plfb Total loading time: 0 Render date: 2024-11-27T23:14:53.152Z Has data issue: false hasContentIssue false
  • English
  • Français

Annular Focused Electron/Ion Beams for Combining High Spatial Resolution with High Probe Current

Published online by Cambridge University Press:  09 September 2016

Anjam Khursheed Open the ORCID record for Anjam Khursheed [Opens in a new window]  and
Wei Kean Ang
Anjam Khursheed*
Affiliation:
Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576, Singapore
Wei Kean Ang
Affiliation:
Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576, Singapore
*
* Corresponding author. [email protected]
Get access

Abstract

This paper presents a proposal for reducing the final probe size of focused electron/ion beam columns that are operated in a high primary beam current mode where relatively large final apertures are used, typically required in applications such as electron beam lithography, focused ion beams, and electron beam spectroscopy. An annular aperture together with a lens corrector unit is used to replace the conventional final hole-aperture, creating an annular ring-shaped primary beam. The corrector unit is designed to eliminate the first- and second-order geometric aberrations of the objective lens, and for the same probe current, the final geometric aberration limited spot size is predicted to be around a factor of 50 times smaller than that of the corresponding conventional hole-aperture beam. Direct ray tracing simulation is used to illustrate how a three-stage core lens corrector can be used to eliminate the first- and second-order geometric aberrations of an electric Einzel objective lens.

Keywords

annular focused electron/ion beamsaberration correctionfocused electron/ion beam columnscore lensesobjective lens
Type
Instrumentation and Techniques Development
Information
Microscopy and Microanalysis , Volume 22 , Issue 5 , October 2016 , pp. 948 - 954
Copyright
© Microscopy Society of America 2016 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Ito, H., Sasaki, Y., Ishitani, T. & Nakayama, Y. (2011). Charged particle beam orbit corrector and charged particle beam apparatus, US Patent 7,947,964 B2, May 24, 2011.Google Scholar
Khursheed, A. (2013). Design of a focused electron beam column for ring-cathode sources. Ultramicroscopy 128, 10–23.Google Scholar
Khursheed, A. & Ang, W.K. (2015). On-axis electrode aberration correctors for scanning electron/ion microscopes. Microsc Microanal 21(Suppl 4), 106–111.Google Scholar
Lenz, F. & Wilska, A.P. (1966/1967). Electron optical systems with annular apertures and with corrected spherical aberration. Optik 24, 383–396.Google Scholar
Lorentz-2EM (Ed.) (2015). Lorentz-2EM, v. 9.3. Canada: Integrated Engineering Software Inc.Google Scholar
Plies, E. (1981). Calculation of electrostatic multitubular core-lenses for a 3D imaging electron microscope: Three-dimensionally imaging electron microscopes, (part IV). Nucl Instrum Meth 187, 217–226.Google Scholar
Spence, J.C.H. (2013). High-Resolution Electron Microscopy, 4th ed Oxford: Oxford University Press. p. 80.CrossRefGoogle Scholar
Takaoka, A., Nishi, R. & Ito, H. (2015). Low-aberration optics for large-angle beam with unit core lenses. Optik 126, 1666–1671.CrossRefGoogle Scholar
Typke, D. (1981). Image aberrations of axially symmetric imaging systems with off-axial rays: Three-dimensionally imaging electron microscopes, (part III). Nucl Instrum Meth 187, 217–226.CrossRefGoogle Scholar