Previous work has shown that the reconstruction of geometric parameters describing the profile of an attenuated phase shift (MoSi) photomask is possible by a least-square minimization of the difference between measurement data and simulation results. Modelling work on other related systems, in particular EUV scatterometry, has revealed a strong influence of the uncertainties assigned to the input data. Their choice may introduce a systematic bias to the determination of the reconstructed geometric quantities like line height, top- and bottom CDs or side-wall angles. Here we employ a maximum likelihood estimation (MLE) to obtain the profile parameters as well as consistent uncertainty estimates for the input data. The method is applied to a set of goniometric scatterometry measurements at a wavelength of 193nm on a state-of-the-art MoSi mask.

Date Published: 23 May 2011
PDF: 6 pages
Proc. SPIE 8083, Modeling Aspects in Optical Metrology III, 808306 (23 May 2011); doi: 10.1117/12.895027

Published in SPIE Proceedings Vol. 8083:
Modeling Aspects in Optical Metrology III
Bernd Bodermann, Editor(s)