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Proceedings Paper

Overlay measurement by angle resolved Mueller polarimetry
Author(s): Clément Fallet; Tatiana Novikova; Aline Jolibois; Bicher Haj Ibrahim; Antonello De Martino; Cyril Vannuffel
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Paper Abstract

The use of optical metrology techniques for process control is now widespread. These techniques are fast and nondestructive, allowing higher throughputs than non-optical techniques like electron microscopies or AFM. We present here new developments using complete Mueller polarimetry in the back focal plane of a microscope objective to characterize overlay for microelectronic industry. Based on fundamental symmetries in the physics of periodic structures and polarized light and redundancies in the angle-resolved Mueller images we define estimators which vary linearly with the overlay. As a result, overlay measurement is sensitive to both the direction and sign of the overlay, and it does not require any detailed modeling of the target structures, provided two independent targets with known overlay values are available in close locations on the wafer. Realistic simulations on optimized structures suggest that accuracies in the order of 1 or 2 nm or better should be achievable. Moreover, with high NA objectives the proposed technique can be implemented with targets with lateral sizes as small as a few μm. Experimental results of both grating line profiles and overlay determinations will be presented. The samples, elaborated at LETI, have been accurately characterized by optical imaging AIM techniques and state-of-the-art AFM. The latest developments on the device itself as well as the advantages, possibilities and limitations of this new metrology technique will be discussed.

Paper Details

Date Published: 10 September 2011
PDF: 11 pages
Proc. SPIE 8160, Polarization Science and Remote Sensing V, 81600J (10 September 2011); doi: 10.1117/12.893805
Show Author Affiliations
Clément Fallet, Ecole Polytechnique (France)
Tatiana Novikova, Ecole Polytechnique (France)
Aline Jolibois, Ecole Polytechnique (France)
Bicher Haj Ibrahim, Ecole Polytechnique (France)
Antonello De Martino, Ecole Polytechnique (France)
Cyril Vannuffel, CEA/LETI MINATEC (France)


Published in SPIE Proceedings Vol. 8160:
Polarization Science and Remote Sensing V
Joseph A. Shaw; J. Scott Tyo, Editor(s)

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