A dedicated multilayer technique for the fabrication of three-dimensional metallic nanoparticles

High resolution electron-beam lithography has been applied to the fabrication of three-dimensional metallic nanostructures. The herein developed fabrication process, which is demonstrated at the example of two ensembles of complex nanoscale particles, comprises a dedicated combination of multilayer electron-beam exposure, vacuum evaporation, lift-off and dry etching. The designs of the two nanostructures rely on the principles of a low degree of spatial symmetry and a high degree of chirality, respectively. Their optical properties are evaluated by means of far-field transmittance spectroscopy. Our fabrication technique delivers an excellent quality of miniaturized three-dimensional nanostructures and yields great potential to be extended towards the fabrication of large-area optical metamaterials composed of truly three-dimensional metallic nanoparticles.

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► Metallic nanoparticles are investigated for their fascinating properties in nanooptics.
► Most metallic nanoparticles are structured as a single functional layer only.
► This limits their degrees of freedom and the potential to explore their symmetry properties.
► We show a dedicated nanoscale technique to fabricate 3D nanoparticles.
► Extraordinary properties, e.g. asymmetric transmission and giant polarization rotation, emerge.