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:
Jun. 11, 2002
Filed:
Sep. 16, 1999
Shintaro Kawata, Saitama-ken, JP;
Nikon Corporation, Tokyo, JP;
Abstract
Methods are provided for performing axial alignment of the optical system in a charged-particle-beam (e.g., electron-beam) microlithographic exposure apparatus employing an illumination beam and a scattering-type reticle. The microlithographic exposure apparatus projects and forms an image of a patterned beam that has passed through a reticle onto a substrate (e.g., semiconductor wafer). The reticle can be a scattering-stencil mask in which feature-defining cutouts are formed in a membrane that transmits an illumination beam while scattering the beam. A contrast aperture is disposed at the beam-convergence plane of the projection lens, i.e., at the Fourier plane of the reticle surface. Axial alignment is performed using an adjustment reticle having a “white subfield” (in a scattering-stencil reticle, a cutout area covering the entire subfield) and a “black subfield” (in a scattering-stencil reticle, a subfield consisting entirely of a reticle membrane lacking any cutouts).