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Proceedings Paper

Improved theoretical reflectivities of extreme ultraviolet mirrors
Author(s): Mandeep Singh; Joseph J. M. Braat
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Paper Abstract

We show that the theoretical reflectivities of multilayered Mo/Be and Mo/Si extreme ultraviolet (EUV) mirrors tuned for the 11 - 14 nm spectral region can be enhanced significantly by incorporating additional materials within the stack. The reflectivity performance of these quarter-wave multilayers can be enhanced further by global optimization procedures by which the layer thicknesses are varied for optimum performance. By incorporating additional materials of differing complex refractive indices -- e.g. Rh, Ru and Sr -- in various regions of the stack we calculate peak reflectivity enhancements of up to approximately 5% for a single reflector compared to standard unoptimized stacks. For an EUV optical system with nine near-normal-incidence mirrors, the theoretical optical throughput may be increased by up to 100%. We also show that protective capping layers such as Rh and Ru, in addition to protecting the mirrors from environmental attack, may serve to improve the reflectivity characteristics.

Paper Details

Date Published: 21 July 2000
PDF: 8 pages
Proc. SPIE 3997, Emerging Lithographic Technologies IV, (21 July 2000); doi: 10.1117/12.390078
Show Author Affiliations
Mandeep Singh, Delft Univ. of Technology (Canada)
Joseph J. M. Braat, Delft Univ. of Technology (Netherlands)


Published in SPIE Proceedings Vol. 3997:
Emerging Lithographic Technologies IV
Elizabeth A. Dobisz, Editor(s)

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