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Proceedings Paper

Substrate recovery layers for EUVL optics: effects on multilayer reflectivity and surface roughness
Author(s): I. Nedelcu; R. W. E. van de Kruijs; A. E. Yakshin; E. Louis; F. Bijkerk; S. Mullender
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Paper Abstract

We have investigated the use of separation, or substrate recovery layers (SRL) enabling the re-usage of optics substrates after deposition of multilayer reflective coatings, in particular Mo/Si multilayers as used for Extreme UV lithography. An organic material, a polyimide, was applied, from other work known to reduce the roughness of the substrate 1, 2. It appeared to be possible to remove the multilayer coating, including the SRL, without any damage or roughening of the substrate surface. The SRL was spin-coated at 1500 - 6000 rpm on different substrate types (Si, quartz, Zerodur) with diameters up to 100 mm. For this range of parameters, the multilayer centroid wavelength value remained unchanged, while its reflectivity loss, upon applying the SRL, was limited to typically 0.7%. The latter is demonstrated to be caused by a minor increase of the SRL surface roughness in the high spatial frequency domain. The AFM characterized roughness remained constant at 0.2 nm during all stages of the substrate recovery process, independent of the initial substrate roughness.

Paper Details

Date Published: 21 March 2007
PDF: 10 pages
Proc. SPIE 6517, Emerging Lithographic Technologies XI, 651730 (21 March 2007); doi: 10.1117/12.712176
Show Author Affiliations
I. Nedelcu, FOM-Institute for Plasma Physics Rijnhuizen (Netherlands)
R. W. E. van de Kruijs, FOM-Institute for Plasma Physics Rijnhuizen (Netherlands)
A. E. Yakshin, FOM-Institute for Plasma Physics Rijnhuizen (Netherlands)
E. Louis, FOM-Institute for Plasma Physics Rijnhuizen (Netherlands)
F. Bijkerk, FOM-Institute for Plasma Physics Rijnhuizen (Netherlands)
S. Mullender, Carl Zeiss SMT AG (Germany)


Published in SPIE Proceedings Vol. 6517:
Emerging Lithographic Technologies XI
Michael J. Lercel, Editor(s)

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