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Proceedings Paper

Film-stress-induced deformation of EUV reflective optics
Author(s): Paul A. Spence; Michael P. Kanouff; Avijit K. Ray-Chaudhuri
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Paper Abstract

Results of numerical studies on the deformation of multilayer coated optics for EUV lithography are presented and compared. The primary materials-dependent characteristics of EUV multilayer mirrors are reflectance, stress, and stability. Understanding and controlling these mirror characteristics is critical for the efficient operation of an EUVL system. Optimized for reflectance, the multilayer coatings typically have film stress values large enough to deform the optic. We use finite element models to predict the distortion caused by the film stress. Input parameters to the models include the size, shape, and material properties of the optical substrate as well as the magnitude and spatial variations of the film stress. The distortion results are coupled with optical analysis software to predict wavefront aberrations for the candidate optical design. Finally, lithographic analysis software is used to predict the aerial image and linewidth variation. Model predictions have guided the design of the optical substrates so that lithographic errors induced by film- stress-deformation are expected to be within the acceptable error budget.

Paper Details

Date Published: 25 June 1999
PDF: 11 pages
Proc. SPIE 3676, Emerging Lithographic Technologies III, (25 June 1999); doi: 10.1117/12.351166
Show Author Affiliations
Paul A. Spence, Sandia National Labs. (United States)
Michael P. Kanouff, Sandia National Labs. (United States)
Avijit K. Ray-Chaudhuri, Sandia National Labs. (United States)

Published in SPIE Proceedings Vol. 3676:
Emerging Lithographic Technologies III
Yuli Vladimirsky, Editor(s)

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