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Applied Optics

Applied Optics


  • Vol. 39, Iss. 13 — May. 1, 2000
  • pp: 2189–2197

Design of multilayer extreme-ultraviolet mirrors for enhanced reflectivity

Mandeep Singh and Joseph J. M. Braat  »View Author Affiliations

Applied Optics, Vol. 39, Issue 13, pp. 2189-2197 (2000)

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We show numerically that the reflectivity of multilayer extreme-UV (EUV) mirrors tuned for the 11–14-nm spectral region, for which the two-component, Mo/Be and Mo/Si multilayer systems with constant layer thickness are commonly used, can be enhanced significantly when we incorporate additional materials within the stack. The reflectivity performance of the quarter-wavelength multilayers can be enhanced further by global optimization procedures with which the layer thicknesses are varied for optimum performance. By incorporating additional materials of differing complex refractive indices—e.g., Rh, Ru, Sr, Pd, and RbCl—in various regions of the stack, we observed peak reflectivity enhancements of as much as ∼5% for a single reflector compared with standard unoptimized stacks. We show that, in an EUV optical system with nine near-normal-incidence mirror surfaces, the optical throughput may be increased by a factor as great as 2. We also show that protective capping layers, in addition to protecting the mirrors from environmental attack, may serve to improve the reflectivity characteristics.

© 2000 Optical Society of America

OCIS Codes
(160.3900) Materials : Metals
(220.3740) Optical design and fabrication : Lithography
(230.1480) Optical devices : Bragg reflectors
(230.4170) Optical devices : Multilayers
(310.6860) Thin films : Thin films, optical properties
(340.7470) X-ray optics : X-ray mirrors

Original Manuscript: September 28, 1999
Revised Manuscript: January 19, 2000
Published: May 1, 2000

Mandeep Singh and Joseph J. M. Braat, "Design of multilayer extreme-ultraviolet mirrors for enhanced reflectivity," Appl. Opt. 39, 2189-2197 (2000)

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