| 摘要 |
PROBLEM TO BE SOLVED: To make shot noise small as in the case of an electron tube and to obtain stable high brightness by using a thermionic emission cathode. SOLUTION: The electron beam apparatus consists of an electron gun 1a with the thermionic emission cathode 1, a condenser lens 12, an NA opening 13 by which an orbit of a primary electron beam is restricted, an objective lens 19, and detectors (23, 24, 25, and 26) which detect secondary electron beams emitted from a sample 20 to which negative voltage has been impressed. The electron gun 1a is operated on space-charge limiting conditions, and the opening 13 is arranged on the sample 20 side of the condenser lens 12. Or the electron gun 1a is operated on conditions in which the brightness depends on an electron gun current greatly, and the feedback control of voltage of a Wehnelt electrode 4 of the electron gun is carried out so that the electron gun current may become an approximately constant value. COPYRIGHT: (C)2004,JPO
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