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A sulfur hexafluoride based reactive ion etching process allowing to etch several micron deep holes with diameters of the order of a few microns in lithium niobate is reported. Etching of deep structures with aspect ratios up to 1.5 was made possible through the use of an electroplated nickel mask exhibiting a selectivity as high as 20 with respect to lithium niobate. Several crystallograpic orientations were investigated, although particular interest was paid to Y-axis oriented substrates. Photoresist as well as metal masks were also tested and their selectivity was compared. The influence of process parameters such as applied rf power or operating pressure on the sidewall slope angle of the etched patterns was investigated. The technique has been successfully applied to the fabrication of phononic crystals consisting of periodical arrays of 9 μm diameter, 10 μm deep holes, with a 10 μm period, and presenting sidewall angles as high as 73° etched in Y-axis oriented lithium niobate. [ABSTRACT FROM AUTHOR]

In this study, the authors have demonstrated that it is possible to realize several three-dimensional (3D) micro- and nanostructures, by the fabrication of the smallest microhouse using a dual beam scanning electron microscope (SEM)/focused ion beam (FIB) Auriga 60 from Zeiss together with a six degree of freedom robot built with SmarAct components. In this new type of nanolab, cutting, etching, folding, assembling, and then welding thin membranes of silica on top of a cleaved optical fiber SMF28, or production of micro- and nanostructures, like the microhouse, are possible. The authors have experimentally shown that FIB can be used, in this new generation of micro/nanofactory, in combination with SEM, and gas injection system, in order to fabricate three-dimensional microstructures: a microhouse in this study, with ultrahigh accuracy assembly down to 10 nm. By using the theory of sputtering, the authors are able to propose a model of folding thin membranes of numerous materials such as metals, polymers, or crystals, i.e., silica, silicon, potassium tantalite, or lithium niobate. This method is usually described as origami in the literature [W. J. Aroa, H. I. Smith, and G. Barbastathis, Microelectron. Eng. 84, 1454 (2007); W. J. Aroa et al., J. Vac. Sci. Technol., B 25, 2184 (2007); and K. Chalapat et al., Adv. Mater. 25, 91 (2013)]. The experimental results indicate that the introduction of a microrobot inside the SEM vacuum chamber will provide the means to enlarge the scope of clean room facilities to build complex and smart 3D microsystems with heterogeneous materials, especially on the facet of an optical fiber in the lab on fiber new field. The authors propose a new way to easily manufacture many kinds of optical functions for light trapping based on nanoantennas, nanophotonic crystal, axicon or lattice, 3D biosensor with origami, and nanopatterning surfaces or carbon nanotubes, etc. [ABSTRACT FROM AUTHOR]