CLEANUP METHOD FOR OPTICAL ELEMENT IN IMMERSION LITHOGRAPHY

摘要

PROBLEM TO BE SOLVED: To provide systems and methods for making maintenance of an optical element of an immersion lithography apparatus easier and thereby improve the useful lifetime of the optical element.SOLUTION: The immersion lithography apparatus includes: a working stage arranged to retain a workpiece; a projection system for projecting an image pattern; a fluid-supplying unit for providing an immersion liquid into a gap defined between an optical element of the projection system and the workpiece during an immersion lithography process; and a cleaning device to clean the optical element during a cleaning process.