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.
The development of silicon nano-crystals (nc-Si or dots) technologies requires important characterization work, and till now suffers from the lack of non-invasive, in-line metrology to control the growth of dots. This paper reports the validation of a new in-line dots size and density characterization, achieved by coupling light scattering analysis and XRay reflectivity measurements. A set of nc-Si with density ranging from 1011 to 6x1011cm-2 and size from 9 to 13nm was grown on Al2O3 / HfO2 stacks and used to validate the correlation between light scattering and dot density, and the correlation between X-Ray reflectivity and dot size. This fast (<10 minutes per wafer) in-line protocol gives very encouraging results, being in good agreement with Scanning Electron Microscopy off-line measurements.