Radiant energy – Inspection of solids or liquids by charged particles – Electron probe type
Patent
1990-03-28
1992-08-25
Anderson, Bruce C.
Radiant energy
Inspection of solids or liquids by charged particles
Electron probe type
250307, H01J 3728
Patent
active
051421488
ABSTRACT:
A field emission scanning electron microscope in which an aperture plate is disposed in a high-vacuum region between an accelerating electrode and a condenser lens. Since a probe current can not be controlled by a lens system with the abovementioned structure, the probe current is controlled by controlling an extracting voltage applied to an extracting electrode. Deviation of the focal point taking place in accompanying a change of a virtual electron source position as brought about by the control of the probe current is corrected by controlling the focal length of a condenser lens such that the electron beam has a constant spread on the principal plane of an objective lens to thereby maintain a beam aperture angle (.alpha..sub.i) at a specimen to be constant.
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patent: 3927321 (1975-12-01), Welter
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patent: 4588891 (1986-05-01), Saito
patent: 4926055 (1990-05-01), Miyokawa
"A High-Resolution Scanning Transmission Electron Microscope", Crewe et al., Journ. of Applied Physics, vol. 39, No. 13, Dec. 1968, pp. 586-568.
Anderson Bruce C.
Hitachi , Ltd.
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