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:
Sep. 26, 2000
Filed:
Aug. 26, 1998
Mamoru Nakasuji, Yokohama, JP;
Shohei Suzuki, Tokyo, JP;
Nikon Corporation, Tokyo, JP;
Abstract
The present invention provides CPB projection apparatus and transfer methods for transferring a pattern from a mask onto a wafer with precise linear-distortion correction of transferred images without creating significant astigmatic blur of the image. A preferred embodiment of the projection apparatus includes an illumination-optical system and a projection-optical system. The illumination-optical system includes a CPB source for emitting a charged-particle beam, and first and second condenser lenses. A field-limiting aperture limits the field of the charged-particle flux. A first astigmatic-aberration correction coil is positioned at a principal plane of either the first or second projection lens and corrects linear distortion of a resulting projected image. A third condenser lens collimates the beam to form an image of the field-limiting aperture on a selected subfield of the mask. A projection-lens system demagnifies the image formed by the mask and projects the demagnified image on a wafer. A crossover aperture is positioned between the projection-lens system to further shape the CPB flux. A second astigmatic-aberration-correction coil is positioned parallel with the crossover aperture to correct astigmatic blur.