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Etched-multilayer phase shifting masks for EUV lithography

United States Patent

April 5, 2005
View the Complete Patent at the US Patent & Trademark Office
Lawrence Livermore National Laboratory - Visit the Industrial Partnerships Office Website
A method is disclosed for the implementation of phase shifting masks for EUV lithography. The method involves directly etching material away from the multilayer coating of the mask, to cause a refractive phase shift in the mask. By etching into the multilayer (for example, by reactive ion etching), rather than depositing extra material on the top of the multilayer, there will be minimal absorption loss associated with the phase shift.
Chapman; Henry N. (Livermore, CA), Taylor; John S. (Livermore, CA)
EUV Limited Liability Corporation (Santa Clara, CA)
10/ 256,377
September 27, 2002
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.