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. 25, 2002
Filed:
Jan. 20, 2000
Nikon Corporation, Tokyo, JP;
Abstract
A laser beam emitted from an exposure laser beam source has a uniform illuminance distribution after passing through a fly-eye lens selected according to the aperture stop. The exposure light is projected onto a reticle on which a predetermined pattern is formed, and the reticle pattern is projected onto a wafer by means of a projection optical system having a pupil filter inserted therein. A cleaning light beam branching off from the exposure light beam is projected through a beam splitter and a total reflection mirror onto the fly-eye lens located at a retraction position. A plane-parallel plate at the retraction position is irradiated with a cleaning light beam. The fly-eye lens and the plane-parallel plate are self-cleansed by the cleaning light beam, so that the transmissivity is kept higher than a predetermined value during standby.