Researchers from CNR-SPIN in collaboration with University of Genoa and QuantifiedAir (NL) developed a novel fabrication protocol to realize pass-through device geometries from oxide thin films deposited on SrTiO3 substrates.
Suspended micro-structures made of epitaxial complex oxides rely on surface micro-machining processes based on sacrificial layers. These processes prevent to physically access the microstructures from both sides, as substantial part of the substrate is not removed. A collaboration between scientists from CNR-SPIN in collaboration with University of Genoa and QuantifiedAir (NL) developed a bulk micro-machining protocol for SrTiO3(100) or SrTiO3(110), a commonly used substrate for the deposition of complex oxide. This process is based on the selective wet etching of the substrate and employs epitaxial oxides thin films as both hard masks and device layers. Thanks to the careful calibration of anisotropic etching rates of SrTiO3, it was possible to control, in a predictable way, the final shape of the aperture in the substrate. As demonstrators of possible device geometries, the team realized clamped membranes and trampolines made of (La,Sr)MnO3, a conductive magnetic oxide, or even carved from the SrTiO3 substrate itself. Reported protocols can be readily applied to a broad variety of other complex oxides so to extend the use of membranes technology beyond those of commercially available silicon compounds.
This research was developed in the framework of the OXiNEMS project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 828784. This work was carried out within the framework of the project “RAISE - Robotics and AI for Socio-economic Empowerment” and has been supported by European Union - NextGenerationEU. The authors acknowledge financial support by MUR under the National Recovery and Resilience Plan (NRRP), Project “Network 4 Energy Sustainable Transition – NEST” (PE0000021).
N. Manca, A. E. Plaza, L. Cichetto, W. J. Venstra, C. Bernini, D. Marré, L. Pellegrino, “Oxide Membranes from Bulk Micro-Machining of SrTiO3 Substrates”. Adv. Sci. 2025, 2412683.
https://doi.org/10.1002/advs.202412683