Paper
21 March 2007 Polarization dependence of multilayer reflectance in the EUV spectral range
Frank Scholze, Christian Laubis, Christian Buchholz, Andreas Fischer, Annett Kampe, Sven Plöger, Frank Scholz, Gerhard Ulm
Author Affiliations +
Abstract
The Physikalisch-Technische Bundesanstalt (PTB) with its laboratory at the electron storage ring BESSY II supports the national and European industry by carrying out high-accuracy at-wavelength measurements in the EUV spectral region, particularly to support the development of EUV lithography, which holds the key to the next generation of computer technology. PTB operates an EUV reflectometry facility, designed for at-wavelength metrology of full-size EUVL optics with a maximum weight of 50 kg and a diameter of up to 550 mm and a micro-reflectometry station for reflectometry with sub 10 μm spatial resolution. An absolute uncertainty of 0.10 % is achieved for peak reflectance, with a reproducibility of 0.05 %. For the center wavelength an uncertainty of 2 pm is achieved with a long-term reproducibility of 1.1 pm and a short-term repeatability below 0.06 pm. Measurements at PTB use linearly polarized radiation, whereas EUV optics are operated with unpolarized sources and the status of polarization changes throughout the optical system. Therefore, to transfer these high-accuracy measurements to the EUV optical components under working conditions, it is essential to study the polarization dependence in detail. The degree of linear polarization in the EUV reflectometer is 97%. Representative polarization dependencies obtained on Mo/Si multilayer coatings over a wide range of angles of incidence reveal that the accuracy of calculations with the IMD-code is presently limited by the optical data available.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Frank Scholze, Christian Laubis, Christian Buchholz, Andreas Fischer, Annett Kampe, Sven Plöger, Frank Scholz, and Gerhard Ulm "Polarization dependence of multilayer reflectance in the EUV spectral range", Proc. SPIE 6517, Emerging Lithographic Technologies XI, 65172W (21 March 2007); https://doi.org/10.1117/12.707867
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KEYWORDS
Polarization

Reflectivity

Extreme ultraviolet

Mirrors

Reflectometry

Extreme ultraviolet lithography

Multilayers

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