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Method for fabricating reticles for EUV lithography without the use of a patterned absorber

United States Patent

October 21, 2003
View the Complete Patent at the US Patent & Trademark Office
Lawrence Livermore National Laboratory - Visit the Industrial Partnerships Office Website
Absorber material used in conventional EUVL reticles is eliminated by introducing a direct modulation in the complex-valued reflectance of the multilayer. A spatially localized energy source such as a focused electron or ion beam directly writes a reticle pattern onto the reflective multilayer coating. Interdiffusion is activated within the film by an energy source that causes the multilayer period to contract in the exposed regions. The contraction is accurately determined by the energy dose. A controllable variation in the phase and amplitude of the reflected field in the reticle plane is produced by the spatial modulation of the multilayer period. This method for patterning an EUVL reticle has the advantages of (1) avoiding the process steps associated with depositing and patterning an absorber layer and (2) providing control of the phase and amplitude of the reflected field with high spatial resolution.
Stearns; Daniel G. (Los Altos, CA), Sweeney; Donald W. (San Ramon, CA), Mirkarimi; Paul B. (Sunol, CA)
The Regents of the University of California (Oakland, CA)
09/ 752,887
December 28, 2000
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.