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DS: Dünne Schichten

DS 6: Anwendung dünner Schichten

DS 6.2: Vortrag

Freitag, 4. März 2005, 14:45–15:00, TU HS110

High resolution actinic defect inspection for EUVL multilayer mask blanks by photoemission electron microscopy — •U. Neuhäusler¹, A. Oelsner², M. Schicketanz³, J. Slieh¹, N. Weber³, U. Kleineberg¹, M. Brzeska¹, A. Wonisch¹, T. Westerwalbesloh¹, H. Brückl¹, M. Escher³, M. Merkel³, G. Schönhense², and U. Heinzmann¹ — ¹Fakultät für Physik, Universität Bielefeld, Postfach 10 01 31, 33501 Bielefeld — ²Institut für Physik, Universität Mainz, Staudingerweg 7, 55128 Mainz — ³Focus GmbH, Am Birkhecker Berg 20, 65510 Hünstetten-Görsroth

Photoemission electron microscopy (PEEM) is a widely used technique for the characterization of surfaces by photoelectron-imaging. As the development of extreme ultraviolet lithography (EUVL) progresses, PEEM becomes also important as a spatially resolving detector for "at-wavelength (13.5 nm)" metrology. We report here on the development of a new PEEM technique utilizing standing wave illumination near normal incidence at the actinic wavelength of 13.5 nm for inspection of buried defects in MoSi-multilayer mask blanks for EUVL. Due to the small escape depth of photoelectrons of just a few nm, structures buried in a bulk sample normally cannot be seen in PEEM. However, in multilayer-coated mask blanks, the incident wavefield propagates several 100 nm deep to the MoSi-multilayer-substrate interface. Thus, wavefront distortions caused by defects can be probed with a PEEM depending on the node/antinode phase condition at the multilayer surface. Experimental results of visualizing programmed defects down to 50 nm size in multilayer test samples will be presented.