Electron-Beam Lithography Fabrication Process Development for a Mid-IR Plasmonic Metasurface with Fine Features

We show the development of a 100 keV electron-beam lithography liftoff fabrication process for a plasmonic metasurface designed to resonate at 15 $\mu$ m. Such a metasurface may prove useful in enhancing mid-IR absorption spectroscopy, e.g. for CO 2 detection. Helium ion beam microscopy and Fourier transform infrared spectroscopy show evidence of the expected resonance, but which has been shifted outside of the measurable range due to variations in exposure and thickness.