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Title: Method to adjust multilayer film stress induced deformation of optics

Abstract

Stress compensating systems that reduces/compensates stress in a multilayer without loss in reflectivity, while reducing total film thickness compared to the earlier buffer-layer approach. The stress free multilayer systems contain multilayer systems with two different material combinations of opposite stress, where both systems give good reflectivity at the design wavelengths. The main advantage of the multilayer system design is that stress reduction does not require the deposition of any additional layers, as in the buffer layer approach. If the optical performance of the two systems at the design wavelength differ, the system with the poorer performance is deposited first, and then the system with better performance last, thus forming the top of the multilayer system. The components for the stress reducing layer are chosen among materials that have opposite stress to that of the preferred multilayer reflecting stack and simultaneously have optical constants that allow one to get good reflectivity at the design wavelength. For a wavelength of 13.4 nm, the wavelength presently used for extreme ultraviolet (EUV) lithography, Si and Be have practically the same optical constants, but the Mo/Si multilayer has opposite stress than the Mo/Be multilayer. Multilayer systems of these materials have practically identical reflectivity curves. Formore » example, stress free multilayers can be formed on a substrate using Mo/Be multilayers in the bottom of the stack and Mo/Si multilayers at the top of the stack, with the switch-over point selected to obtain zero stress. In this multilayer system, the switch-over point is at about the half point of the total thickness of the stack, and for the Mo/Be--Mo/Si system, there may be 25 deposition periods Mo/Be to 20 deposition periods Mo/Si.« less

Inventors:
 [1];  [2];  [3];  [2];  [3]
  1. Mount Kisco, NY
  2. Sunol, CA
  3. Livermore, CA
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
OSTI Identifier:
873322
Patent Number(s):
US 6134049
Assignee:
Regents of University of California (Oakland, CA)
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
method; adjust; multilayer; film; stress; induced; deformation; optics; compensating; systems; reduces; compensates; loss; reflectivity; reducing; total; thickness; compared; earlier; buffer-layer; approach; free; contain; material; combinations; opposite; design; wavelengths; main; advantage; reduction; require; deposition; additional; layers; buffer; layer; optical; performance; wavelength; poorer; deposited; forming; top; components; chosen; materials; preferred; reflecting; stack; simultaneously; constants; allow; 13; nm; presently; extreme; ultraviolet; euv; lithography; practically; identical; curves; example; multilayers; formed; substrate; bottom; switch-over; selected; obtain; zero; half; be-mo; 25; periods; 20; optical constants; optical performance; multilayer film; additional layers; film thickness; buffer layer; extreme ultraviolet; reducing total; stress induced; multilayer systems; total thickness; stress reducing; induced deformation; film stress; additional layer; systems contain; adjust multilayer; /359/

Citation Formats

Spiller, Eberhard A, Mirkarimi, Paul B, Montcalm, Claude, Bajt, Sasa, and Folta, James A. Method to adjust multilayer film stress induced deformation of optics. United States: N. p., 2000. Web.
Spiller, Eberhard A, Mirkarimi, Paul B, Montcalm, Claude, Bajt, Sasa, & Folta, James A. Method to adjust multilayer film stress induced deformation of optics. United States.
Spiller, Eberhard A, Mirkarimi, Paul B, Montcalm, Claude, Bajt, Sasa, and Folta, James A. Sat . "Method to adjust multilayer film stress induced deformation of optics". United States. https://www.osti.gov/servlets/purl/873322.
@article{osti_873322,
title = {Method to adjust multilayer film stress induced deformation of optics},
author = {Spiller, Eberhard A and Mirkarimi, Paul B and Montcalm, Claude and Bajt, Sasa and Folta, James A},
abstractNote = {Stress compensating systems that reduces/compensates stress in a multilayer without loss in reflectivity, while reducing total film thickness compared to the earlier buffer-layer approach. The stress free multilayer systems contain multilayer systems with two different material combinations of opposite stress, where both systems give good reflectivity at the design wavelengths. The main advantage of the multilayer system design is that stress reduction does not require the deposition of any additional layers, as in the buffer layer approach. If the optical performance of the two systems at the design wavelength differ, the system with the poorer performance is deposited first, and then the system with better performance last, thus forming the top of the multilayer system. The components for the stress reducing layer are chosen among materials that have opposite stress to that of the preferred multilayer reflecting stack and simultaneously have optical constants that allow one to get good reflectivity at the design wavelength. For a wavelength of 13.4 nm, the wavelength presently used for extreme ultraviolet (EUV) lithography, Si and Be have practically the same optical constants, but the Mo/Si multilayer has opposite stress than the Mo/Be multilayer. Multilayer systems of these materials have practically identical reflectivity curves. For example, stress free multilayers can be formed on a substrate using Mo/Be multilayers in the bottom of the stack and Mo/Si multilayers at the top of the stack, with the switch-over point selected to obtain zero stress. In this multilayer system, the switch-over point is at about the half point of the total thickness of the stack, and for the Mo/Be--Mo/Si system, there may be 25 deposition periods Mo/Be to 20 deposition periods Mo/Si.},
doi = {},
url = {https://www.osti.gov/biblio/873322}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2000},
month = {1}
}

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