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:
Aug. 12, 2003
Filed:
Sep. 10, 2001
Shohei Suzuki, Hukaya, JP;
Nikon Corporation, Tokyo, JP;
Abstract
Charged-particle-beam (CPB) microlithography methods and apparatus are disclosed with which large single-shot image-transfer regions (subfields) can be exposed using maximal beam current. Beam current is changed over a selected range to determine a suitable range of beam-spread angles that include the maximum permissible values for average blur, &Dgr;blur, and distortion. Assuming that that range of beam-spread half-angles is between &agr; and &agr; , then the beam current for which &agr; is designated as a cutoff beam current. The beam-spread half-angle at that beam current is the optimal beam-spread half-angle. The ratio between the distribution half-angle and the cutoff half-angle is varied, and a determination is made of the distribution half-angle and cutoff half-angle that will accommodate the greatest beam current. Thus, a maximum beam current can be used while maintaining blur and distortion of the projected subfield image within specified values set for them.