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High numerical aperture ring field projection system for extreme ultraviolet lithography

United States Patent

6,033,079
March 7, 2000
View the Complete Patent at the US Patent & Trademark Office
Lawrence Livermore National Laboratory - Visit the Industrial Partnerships Office Website
An all-refelctive optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first concave mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receives a chief ray at an incidence angle less than substantially 12.degree., and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 15.degree.. Four of the six reflecting surfaces have an aspheric departure of less than substantially 7 .mu.m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 14 .mu.m. Each of the six refelecting surfaces has an aspheric departure of less than 16.0 .mu.m.
Hudyma; Russell (San Ramon, CA)
09/ 270,127
March 15, 1999
The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the United States Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.