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Proceedings Paper

Decorrelation of fitting parameters by Mueller polarimetry in conical diffraction
Author(s): Antonello De Martino; Tatiana Novikova; Christophe Arnold; Sami BenHatit; Bernard Drévillon
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Paper Abstract

We used full Mueller polarimetry in conical diffraction geometries to characterize 1D holographic optical gratings etched in bulk silica with a patterned photoresist layer. We studied four different samples corresponding to different stages of etching, with a Mueller polarimeter based on ferroelectric liquid crystals, operated in the visible. Two samples were also characterized by standard spectroscopic ellipsometry (SE) in the UV-VIS range (300-800 nm). The measured spectra were fitted with a Rigorous Coupled Wave Analysis code with different models of grating profiles. With the Mueller spectra the model adequacy could be assessed from the stability of the optimal values of the fitting parameters when the azimuthal angle was varied. The conclusions were found to be in agreement with AFM images of the sample, while the fits of the SE data were too poor to provide any information in this respect. A key issue for process control is resist-silica interface localization, a difficult task due to the low index contrast for these two materials. In fact, strong correlation occurs between resist and silica thicknesses when SE spectra, taken in the usual planar diffraction geometry, are fitted. Our approach clearly reduces such parameter correlations, leading to a reliable localization of this interface.

Paper Details

Date Published: 24 March 2006
PDF: 12 pages
Proc. SPIE 6152, Metrology, Inspection, and Process Control for Microlithography XX, 61521H (24 March 2006); doi: 10.1117/12.654834
Show Author Affiliations
Antonello De Martino, Lab. de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, École Polytechnique (France)
Tatiana Novikova, Lab. de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, École Polytechnique (France)
Christophe Arnold, Jobin Yvon (France)
Sami BenHatit, Lab. de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, École Polytechnique (France)
Bernard Drévillon, Lab. de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, École Polytechnique (France)


Published in SPIE Proceedings Vol. 6152:
Metrology, Inspection, and Process Control for Microlithography XX
Chas N. Archie, Editor(s)

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