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Optimized capping layers for EUV multilayers

United States Patent

August 24, 2004
View the Complete Patent at the US Patent & Trademark Office
Lawrence Livermore National Laboratory - Visit the Industrial Partnerships Office Website
A new capping multilayer structure for EUV-reflective Mo/Si multilayers consists of two layers: A top layer that protects the multilayer structure from the environment and a bottom layer that acts as a diffusion barrier between the top layer and the structure beneath. One embodiment combines a first layer of Ru with a second layer of B.sub.4 C. Another embodiment combines a first layer of Ru with a second layer of Mo. These embodiments have the additional advantage that the reflectivity is also enhanced. Ru has the best oxidation resistance of all materials investigated so far. B.sub.4 C is an excellent barrier against silicide formation while the silicide layer formed at the Si boundary is well controlled.
Bajt; Sasa (Livermore, CA), Folta; James A. (Livermore, CA), Spiller; Eberhard A. (Livermore, CA)
EUV LLC (Santa Clara, CA)
10/ 066,108
February 1, 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.