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Passivating overcoat bilayer for multilayer reflective coatings for extreme ultraviolet lithography

United States Patent

September 28, 1999
View the Complete Patent at the US Patent & Trademark Office
Lawrence Livermore National Laboratory - Visit the Industrial Partnerships Office Website
A passivating overcoat bilayer is used for multilayer reflective coatings for extreme ultraviolet (EUV) or soft x-ray applications to prevent oxidation and corrosion of the multilayer coating, thereby improving the EUV optical performance. The overcoat bilayer comprises a layer of silicon or beryllium underneath at least one top layer of an elemental or a compound material that resists oxidation and corrosion. Materials for the top layer include carbon, palladium, carbides, borides, nitrides, and oxides. The thicknesses of the two layers that make up the overcoat bilayer are optimized to produce the highest reflectance at the wavelength range of operation. Protective overcoat systems comprising three or more layers are also possible.
Montcalm; Claude (Livermore, CA), Stearns; Daniel G. (Los Altos, CA), Vernon; Stephen P. (Pleasanton, CA)
Regents of the University of California (Oakland, CA)
08/ 969,411
November 10, 1997
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.