Transverse chromatic aberration in a symmetric magnetic doublet with dynamically compensated field aberrations
作者:
Mamoru Nakasuji,
Hiroyasu Shimizu,
期刊:
Journal of Vacuum Science&Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena
(AIP Available online 1995)
卷期:
Volume 13,
issue 4
页码: 1508-1513
ISSN:1071-1023
年代: 1995
DOI:10.1116/1.588178
出版商: American Vacuum Society
关键词: LITHOGRAPHY;ELECTRON BEAMS;LENSES;CHROMATIC ABERRATIONS;BEAM OPTICS;MAGNETIC FIELDS;TRAJECTORIES
数据来源: AIP
摘要:
Radial and azimuthal transverse chromatic aberrations, which are calculated from the electron trajectories, are much larger than those calculated from the axial magnetic field distribution and its first derivative. The generation mechanism for such large transverse chromatic aberrations is assumed to be that the electron trajectories initiated at the same object position with different beam energies travel through different paths. This assumption is roughly confirmed by studying the crossover position deviation and the magnetic vector potentials as a function of radius along theZaxis and their curvature. When the object side and image side lenses are shifted in the crossover direction by 32 and 8 mm, respectively, the azimuthal and radial transverse chromatic aberrations are 1.9 and 1.3 nm/eV for a field size of 20×0.25 mm2and a beam energy of 100 keV. The radial and azimuthal distortions in the subfield are much smaller than 10 nm, when the radial subfield size is 250 μm and the target rotation is corrected.
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