Optical “nanocaliper” system for thin-film metrology and rheology
Our work on nanoimprint modeling showed that better experimental techniques were needed to characterize the rheology of candidate imprintable materials, and the boundary conditions between them and the stamp and substrate surfaces. We therefore proposed and prototyped a chip-scale imprinting device that fits beneath a white-light microscope. By imaging the optical interference that results from multiple reflections within the polymer film, it gives real-time estimates of how the film thins under load. Analysis of this “nanocaliper” indicates that sub-nanometer thickness resolution is achievable with simple light-emitting-diode illumination and a basic video camera. From these measurements, rheological properties can be estimated, and end-point detection for industrial imprint processes becomes possible. Other potential applications include imaging van der Waals solids during and after mechanical exfoliation, and characterizing complex biological fluids. The analysis software is available on nanoHUB as the Nanoscale Viscosity Extractor.
Key publications
[C6] H. Gramling and H. Taylor, “Nanometer-resolution, wide-field optical measurement of time-varying sub-micron fluid film thicknesses for viscosity determination,” in Proc. Micro and Nano Engineering, Vienna, Austria, Sep. 2016. proceedings .pdf
[NC19] H.K. Taylor and N. Dhakal, “A chip-scale imprinter with integrated optical interference for calibrating models of NIL resists and resist-stamp boundary conditions”, presented at Nanoimprint and Nanoprint Technology, Barcelona, Spain, Oct. 2013. abstract .pdf | presentation .pdf
[S4] Hannah Gramling, Yunsu Park, and Hayden Taylor (2019), “Nanoscale Viscosity Extractor,” https://nanohub.org/resources/nanovisc (DOI: doi:10.21981/RTJQ-WH04).