Electron beam control method, electron beam generating apparatus, apparatus using the same, and emitter

摘要

Provided is a Schottky emitter having the conical end with a radius of curvature of 2.0 μm on the emission side of an electron beam. Since a radius of curvature is 1 μm or more, a focal length of an electron gun can be longer than in a conventional practice wherein a radius of curvature is in the range of from 0.5 μm to not more than 0.6 μm. The focal length was found to be roughly proportional to the radius of the curvature. Since the angular current intensity (the beam current per unit solid angle) is proportional to square of the electron gun focal length, the former can be improved by an order of magnitude within a practicable increase in the emitter radius. A higher angular current intensity means a larger beam current available from the electron gun and the invention enables the Schottky emitters to be used in applications which require relatively high beam current of microampere regime such as microfocus X-ray tube, electron probe micro-analyzer, and electron beam lithography system.

主权项

1. An electron beam control method comprising an electron beam generating step of emitting electrons from the conical end of an emitter sharpened in the shape of a cone on the emission side of an electron beam by using a Schottky effect under an electric field applied to the conical end to thereby generate an electron beam, the method further comprising:
a curvature radius adjusting step of adjusting a radius of curvature of the conical end; an electron gun focal length control step of controlling an electron gun focal length of an electron beam by a radius of curvature adjusted in the curvature radius adjusting step; and an angular current density control step of controlling an angular current density of an electron beam with a focal length controlled by the electron gun focal length control step, wherein the electron beam generating step is conducted each time emission of an electron beam in a state where an angular current density is controlled after the angular current density control step.