Regensburg 2013 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 18: Micro- and Nanopatterning (jointly with O)
DS 18.8: Vortrag
Mittwoch, 13. März 2013, 11:15–11:30, H8
Characterization of high-end photomasks by spectroscopic ellipsometry — •Anett Heinrich1, Ingo Dirnstorfer1, Thomas Mikolajick1, Jörg Bischoff2, and Uwe Richter3 — 1NaMLab gGmbH, 01187 Dresden, Germany — 2Osires, 98693 Ilmenau, Germany — 3Sentech Instruments GmbH, 12489 Berlin, Germany
We evaluated spectroscopic ellipsometry as an optical metrology method to determine critical parameters on nanostructured photomasks in high resolution and short process time. An industrial opaque MoSi on glass (OMOG) photomask with line/space gratings consisting of pitches between 280 and 640 nm and different duty cycles was analyzed. The polarization-dependent diffraction effects in Psi and Delta were measured in a wavelength range of 320 to 800 nm. The mask parameters were determined by modeling the ellipsometric response with the rigorous coupled wave analysis (RCWA) method. It was found that the pitch could be determined within sub-nm accuracy down to 130 nm, where the rayleigh singularities move out of the spectral range. The simulated critical dimension (CD) values are systematically smaller than the nominal mask CD. This CD offset was between 10 to 25 nm depending on the absolute CD. A through pitch sensitivity analysis showed that the evaluated metrology is sensitive to CD variations even for sub-50 nm features.