11 October 2012 Performances and limitations of Lab-to-Fab strategies for inline optical metrology
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Critical to the realization of robust nanomanufacturing is the development of appropriate metrology protocols. In the Lab-to-Fab approach, the key properties of materials and stacks of interest are accurately probed with at-line and off-line characterization tools. These Lab-deduced properties propagate to Fab tools which allow for fast non-destructive measurements on product wafers. For instance, the combination of at-line X-ray reflectometry (XRR) and variable-angle spectroscopic ellipsometry (VASE) allows for determination of highly reliable optical constants that can be implemented on inline spectroscopic ellipsometers and reflectometers so as to achieve automated measurements on product wafers. We will first comment on the need for combined XRR-VASE Lab-to-Fab strategies. Secondly, we will point out some limitations of the Lab to Fab strategies. Even though Lab and Fab analysis are performed on the same sample, the material properties may vary due to oxidation, aging or contamination. Moreover, Lab-to-Fab approach must be implemented carefully since parameters such as thickness and roughness of surface and interfacial layers are not probed identically by X-ray based and optically-based techniques. Lastly, among a set of optically-based tools, the various capabilities relating to instrumental function, spectral range and ability to collect reliable depolarisation and anisotropyrelated data may impact the accuracy of Lab-to-Fab strategy.
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E. Nolot, E. Nolot, A. André, A. André, A. Michallet, A. Michallet, } "Performances and limitations of Lab-to-Fab strategies for inline optical metrology", Proc. SPIE 8466, Instrumentation, Metrology, and Standards for Nanomanufacturing, Optics, and Semiconductors VI, 846605 (11 October 2012); doi: 10.1117/12.928368; https://doi.org/10.1117/12.928368

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