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Accuracy analysis of a stand-alone EUV spectrometer for the characterization of ultrathin films and nanoscale gratings

: Schröder, Sophia; Bahrenberg, Lukas; Eryilmaz, Nimet Kutay; Glabisch, Sven; Danylyuk, Serhiy; Brose, Sascha; Stollenwerk, Jochen; Loosen, Peter


Naulleau, Patrick P. (Ed.) ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Extreme Ultraviolet Lithography 2020 : 21-25 September 2020, Online Only
Bellingham, WA: SPIE, 2020 (Proceedings of SPIE 11517)
ISBN: 978-1-5106-3842-6
ISBN: 978-1-5106-3843-3
Paper 115170S, 13 S.
Conference "Extreme Ultraviolet Lithography" <2020, Online>
Fraunhofer ILT ()
metrology; semiconductor lasers; grazing incidence reflectometry; extreme ultraviolet lithography; critical dimension metrology

In this contribution the accuracy of measurements performed with a stand-alone EUV spectrometer is analyzed. The setup is used to determine optical constants and dimensional characteristics of samples, e.g. ultrathin films or nanoscale gratings. For this purpose, measurements of the broadband EUV reflectance of the samples at variable grazing incidence angles are used to reconstruct sample parameters in a model-based approach. The accuracy of these measurements is a crucial factor for a reliable characterization of samples. We present an overview on the sources of uncertainties in the experimental setup as well as improvements to the setup that improves its accuracy. Additionally, the reconstruction accuracy of the optical constants is analyzed. A focus is put on the influence of the experimental uncertainty and the range of incidence angles used for reflectance measurements.