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Proceedings Paper

Characterization of gratings by Mueller polarimetry in conical diffraction
Author(s): Antonello De Martino; Tatiana Novikova; Sami BenHatit; Bernard Drevillon; Denis Cattelan
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Paper Abstract

Spectroscopic Ellipsometry is widely used to characterize 1D gratings in the usual planar diffraction geometry, with grating grooves perpendicular to the incidence plane. The Jones matrix of the grating is then diagonal, and it can be measured properly by any conventional ellipsometer. On the other hand, if the grating is measured at different azimuthal angles, i.e. in conical diffraction geometries, its Jones matrix is no longer diagonal. As a result, additional information is available about the grating groove shape, but a generalized ellipsometer, or a Mueller polarimeter, are necessary to retrieve this information completely. We used this approach with photoresist gratings deposited on Si for nominal CDs down to 70 nm. The instrument was an original Mueller polarimeter based on ferroelectric liquid crystals, and operated in the visible. The measured spectra were fitted with a RCWA code suitable for conical diffraction, with rectangular and trapezoidal profiles. This approach proved to greatly reduce the parameter correlations observed with standard SE for very small CDs. The relevance of the trapezoidal profile can be established, and top and bottom CDs can be "disentangled" much more easily than with standard planar diffraction geometry.

Paper Details

Date Published: 10 May 2005
PDF: 12 pages
Proc. SPIE 5752, Metrology, Inspection, and Process Control for Microlithography XIX, (10 May 2005); doi: 10.1117/12.600537
Show Author Affiliations
Antonello De Martino, LIPCM-CNRS, Ecole Polytechnique (France)
Tatiana Novikova, LIPCM-CNRS, Ecole Polytechnique (France)
Sami BenHatit, LIPCM-CNRS, Ecole Polytechnique (France)
Bernard Drevillon, LIPCM-CNRS, Ecole Polytechnique (France)
Denis Cattelan, Jobin Yvon, Groupe HORIBA (France)

Published in SPIE Proceedings Vol. 5752:
Metrology, Inspection, and Process Control for Microlithography XIX
Richard M. Silver, Editor(s)

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