MAGNETIC LENS ASSEMBLY AND APPARATUS FOR PROJECTION LITHOGRAPHY

摘要

PURPOSE: A magnetic lens assembly and apparatus for projection lithography are provided to reduce magnetic distortion. CONSTITUTION: The apparatus has at least one magnetic lens. The lens is provided with a segmented magnetic liner inside. The segmented liner consists of the segments of magnetic materials alternate with the segments of non- magnetic materials. The liner is continued through the lens. Both the lens and the liner share the same optical axis. The liner practically removes a distortion in the magnetic field of the lens. Further, the liner provides the density of magnetic flux less than saturation within the lens.