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Method to adjust multilayer film stress induced deformation of optics

United States Patent

6,011,646
January 4, 2000
View the Complete Patent at the US Patent & Trademark Office
Lawrence Livermore National Laboratory - Visit the Industrial Partnerships Office Website
A buffer-layer located between a substrate and a multilayer for counteracting stress in the multilayer. Depositing a buffer-layer having a stress of sufficient magnitude and opposite in sign reduces or cancels out deformation in the substrate due to the stress in the multilayer. By providing a buffer-layer between the substrate and the multilayer, a tunable, near-zero net stress results, and hence results in little or no deformation of the substrate, such as an optic for an extreme ultraviolet (EUV) lithography tool. Buffer-layers have been deposited, for example, between Mo/Si and Mo/Be multilayer films and their associated substrate reducing significantly the stress, wherein the magnitude of the stress is less than 100 MPa and respectively near-normal incidence (5.degree.) reflectance of over 60% is obtained at 13.4 nm and 11.4 nm. The present invention is applicable to crystalline and non-crystalline materials, and can be used at ambient temperatures.
Mirkarimi; Paul B. (Sunol, CA), Montcalm; Claude (Livermore, CA)
The Regents of the Unviersity of California (Oakland, CA)
09/ 027,309
February 20, 1998
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.