Patterning of Complex, Nanometer-Scale Features in Wide-Area Gold Nanoplasmonic Structures Using Helium Focused Ion Beam Milling

Meeting the evolving demands of plasmonics research requires increasingly precise control over surface plasmon properties, which necessitates extremely fine nanopatterning, complex geometries, and/or long-range order. Nanoplasmonic metasurfaces are representative of a modern research area requiring intricate, high-fidelity features reproduced over areas of several free-space wavelengths, making them one of the most challenging fabrication problems in the field today. This work presents a systematic study of the helium focused ion beam milling of gold for nanoplasmonic metasurface applications, using as its example a nanoplasmonic metasurface based on an array of nanometer-scale plasmonic-wire-loaded subwavelength apertures in a gold film. At each step, the pattern variations are compared to simulation to predict the experimental outcome. Our results show that even in a practical fabrication environment, helium ion beam milling can be used to reliably pattern 10 nm features into gold with 1:5 aspect ratio in complex geometries over a wide area.

Automated summary

This study systematically investigates the use of helium focused ion beam milling of gold for nanoplasmonic metasurface applications, demonstrating the reliable patterning of 10 nm features into gold with complex geometries over a wide area. The results provide strong support for the application of nanoplasmonic metasurfaces in modern research areas.