Scanning electron microscope calibration with simultaneous electron probe diameter determination

The resolution of a conventional transmission electron microscope (TEM) deteriorates as the specimen thickness increases, because chromatic aberration of the objective lens is caused by the energy loss of electrons). In the case of a scanning electron microscope (SEM), chromatic aberration does not exist as the restrictive factor for the resolution of the transmitted electron image, for the SEM has no imageforming lens. It is not sure, however, that the equal resolution to the probe diameter can be obtained in the case of a thick specimen. To study the relation between the specimen thickness and the resolution of the trans-mitted electron image obtained by the SEM, the following experiment was carried out.

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High Resolution Scanning Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086696 ◽

1991 ◽

Vol 49 ◽

pp. 478-479

Author(s):

David Joy ◽

James Pawley

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Electron Beam ◽

Electron Microscope ◽

High Resolution ◽

Scanning Electron Microscope ◽

Electron Probe ◽

Impact Point ◽

Interaction Volume ◽

Scanning Electron

The scanning electron microscope (SEM) builds up an image by sampling contiguous sub-volumes near the surface of the specimen. A fine electron beam selectively excites each sub-volume and then the intensity of some resulting signal is measured. The spatial resolution of images made using such a process is limited by at least three factors. Two of these determine the size of the interaction volume: the size of the electron probe and the extent to which detectable signal is excited from locations remote from the beam impact point. A third limitation emerges from the fact that the probing beam is composed of a finite number of discrete particles and therefore that the accuracy with which any detectable signal can be measured is limited by Poisson statistics applied to this number (or to the number of events actually detected if this is smaller).

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The Observation of NBC Precipitates In Steels In The Nanometer Range Using A Field Emission Gun Scanning Electron Microscope

Microscopy and Microanalysis ◽

10.1017/s1431927600013106 ◽

1997 ◽

Vol 3 (S2) ◽

pp. 1243-1244 ◽

Cited By ~ 1

Author(s):

Raynald Gauvin ◽

Steve Yue

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Field Emission ◽

Incident Electron Energy ◽

Beam Diameter ◽

Probe Diameter ◽

Transmission Electron ◽

Electron Microscopes ◽

Scanning Electron Microscopes ◽

Scanning Electron

The observation of microstructural features smaller than 300 nm is generally performed using Transmission Electron Microscopy (TEM) because conventional Scanning Electron Microscopes (SEM) do not have the resolution to image such small phases. Since the early 1990’s, a new generation of microscopes is now available on the market. These are the Field Emission Gun Scanning Electron Microscope with a virtual secondary electron detector. The field emission gun gives a higher brightness than those obtained using conventional electron filaments allowing enough electrons to be collected to operate the microscope with incident electron energy, E0, below 5 keV with probe diameter smaller than 5 nm. At 1 keV, the electron range is 60 nm in aluminum and 10 nm in iron (computed using the CASINO program). Since the electron beam diameter is smaller than 5 nm at 1 keV, the resolution of these microscopes becomes closer to that of TEM.

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Improving Scanning Electron Microscope Resolution for Near Planar Samples Through the Use of Image Restoration

Microscopy and Microanalysis ◽

10.1017/s1431927613013688 ◽

2013 ◽

Vol 20 (1) ◽

pp. 78-89 ◽

Cited By ~ 8

Author(s):

Eric Lifshin ◽

Yudhishthir P. Kandel ◽

Richard L. Moore

Keyword(s):

Electron Microscope ◽

High Resolution ◽

Scanning Electron Microscope ◽

Accurate Determination ◽

Limiting Factor ◽

Beam Shape ◽

Probe Diameter ◽

High Resolution Images ◽

Beam Currents ◽

Scanning Electron

AbstractA method is presented for determining the point spread function (PSF) of an electron beam in a scanning electron microscope for the examination of near planar samples. Once measured, PSFs can be used with two or more low-resolution images of a selected area to create a high-resolution reconstructed image of that area. As an example, a 4× improvement in resolution for images is demonstrated for a fine gold particle sample. Since thermionic source instruments have high beam currents associated with large probe sizes, use of this approach implies that high-resolution images can be produced rapidly if the probe diameter is less of a limiting factor. Additionally, very accurate determination of the PSFs can lead to a better understanding of instrument performance as exemplified by very accurate measurement of the beam shape and therefore the degree of astigmatism.

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