The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 03, 2002
Filed:
May. 18, 2000
Koichi Kamijo, Kawasaki, JP;
Nikon Corporation, Tokyo, JP;
Abstract
Astigmatism-correction devices are disclosed for use in a charged-particle-beam (CPB) microlithography apparatus and methods and that do not produce higher-order aberrations when correcting deflection aberrations. The CPB microlithography apparatus includes a projection-optical system that includes first and second projection lenses and associated deflectors. The astigmatism-correction device can include a first coil array associated with the first projection lens upstream of an aperture, and a second astigmatism-correction device associated with the second projection lens downstream of the aperture. In each coil array, the nominal half-angle of the constituent coils is 30°. With such a configuration, higher-order aberrations that otherwise would be produced by the deflectors are reduced nearly to zero, making it possible to use large electrical currents in the deflectors. Specifically, deflection-astigmatism aberrations and hybrid deflection-astigmatic distortions otherwise produced by the deflectors are eliminated.