Application of a thermal field emission source for high resolution, high current e‐beam microprobes

1979 ◽  
Vol 16 (6) ◽  
pp. 1699-1703 ◽  
Author(s):  
D. Tuggle ◽  
L. W. Swanson ◽  
J. Orloff
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Thermal Field ◽  
Emission Source ◽  
High Current

A High Resolution Scanning Microscope

1968 ◽  
Vol 26 ◽  
pp. 356-357
Author(s):  
A. V. Crewe ◽  
J. Wall ◽  
L. M. Welter
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Spherical Aberration ◽  
Focal Length ◽  
Spot Size ◽  
Emission Source ◽  
Field Of View ◽  
Scanning Microscope ◽  
Magnetic Lens ◽  
High Quality

A scanning microscope using a field emission source has been described elsewhere. This microscope has now been improved by replacing the single magnetic lens with a high quality lens of the type described by Ruska. This lens has a focal length of 1 mm and a spherical aberration coefficient of 0.5 mm. The final spot size, and therefore the microscope resolution, is limited by the aberration of this lens to about 6 Å.The lens has been constructed very carefully, maintaining a tolerance of + 1 μ on all critical surfaces. The gun is prealigned on the lens to form a compact unit. The only mechanical adjustments are those which control the specimen and the tip positions. The microscope can be used in two modes. With the lens off and the gun focused on the specimen, the resolution is 250 Å over an undistorted field of view of 2 mm. With the lens on,the resolution is 20 Å or better over a field of view of 40 microns. The magnification can be accurately varied by attenuating the raster current.

Dual Stage SEM with thermal field-emission gun

1989 ◽  
Vol 47 ◽  
pp. 94-95
Author(s):  
S. Yamazaki ◽  
T. Sato ◽  
S. Aota ◽  
R. Buchanan
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Thermal Field ◽  
Objective Lens ◽  
Wide Field ◽  
Operating Voltage ◽  
High Brightness ◽  
Voltage Range ◽  
Optical Configuration ◽  
Working Distance

Resolution improvement is an on-going goal in scanning electron microscope development. High resolution is required at both high and low accelerating voltages in a wide field of applications, including, but not exclusive to, semiconductors and new materials development. Two approaches which result in improved resolution through-out the operating voltage range of the SEM are 1) the adoption of low aberration objective lenses, and 2) the use of high brightness electron sources.The DS-130F SEM which is described here uses a high brightness thermal field emission gun (TFEG) in conjunction with a modified DS-130 column. The electron optical configuration is quite unique, as it includes two independent stages. The top stage places the sample within a high field strength low aberration objective lens, resulting in ultra high resolution on samples up to 18 x 8 mm. The bottom stage accommodates 6” samples and uses a second dedicated conical objective lens allowing a short working distance to be maintained on tilted samples.

Stem Dark-Field Image Using A 200-kV AEM

1996 ◽  
Vol 54 ◽  
pp. 444-445
Author(s):  
T. Tomita ◽  
T. Honda ◽  
M. Kersker
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Thermal Field ◽  
Imaging System ◽  
Dark Field Image ◽  
Dark Field ◽  
Specimen Thickness ◽  
High Angle ◽  
Long Term Stability ◽  
Annular Dark Field

Interpretation of the high resolution transmission image typically requires simulation since the contrast changes in a complicated way due to changes in focus and specimen thickness. The contrast in images formed by collecting high angle forward scattered electrons in STEM does not change with changes in thickness or defocus.Until recently, high angle annular dark field (HADF) images were obtained only from instruments using cold field emission guns. Recently we have attempted to obtain HADF images using Schottky (ZrO/W(100)) thermal field emission and using a 200kV instrument designed as a comprehensive TEM/STEM. Advantages of the ZrO/W emitter are easy operation, very good short and long term stability, high brightness, and narrow energy spread. This microscope, The JEM2010F with thermal field emission, allows subnanometer analysis with EDS(spot, line, and mapping), EELS, holograms, etc, and has a standard TEM imaging system for high resolution imaging and for various diffraction modes, viz., CBED, selected area, Tanaka, etc.

High Resolution Scanning Microscopy

1969 ◽  
Vol 27 ◽  
pp. 172-173 ◽  
Author(s):  
A. V. Crewe ◽  
J. Wall
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Focal Length ◽  
Emission Source ◽  
Scanning Microscopy ◽  
Objective Lens ◽  
Scanning Microscope ◽  
Current Point ◽  
Single Objective

We have previously reported on the development of a scanning microscope with a resolution of 20 Å. This instrument has now been improved so that the current point resolution is about 5 Å at 18 Kv.The microscope consists of a field emission gun followed by a single objective lens (see Fig. 1). The gun produces an image (real or virtual) of the field emission source which is then demagnified by the lens. The focal length of this lens has been shortened from 1 mm to 0.6 mm to produce a second beam crossover at the exit of the lens.

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