Fabrication of metallic nanostructures for investigating plasmon-induced field enhancement

摘要

High resolution metallic nanostructures with well-defined geometry, such as antennae, cones and rods, are essential for nanophotonics and plasmonics. In order to fabricate such structures, we use the negative electron beam resist hydrogen silsesquioxane (HSQ) as an etch mask for an underlying metal stack. By exposing the resist and developing it in tetramethyl ammonium hydroxide (TMAH), structures with dimensions of few tens of nanometers can be fabricated. Afterwards the surrounding metal is removed by ion milling. Finally, the HSQ is lifted off via a sacrificial chromium layer. The process was used to fabricate arrays of cones and antennae of different sizes, either resonant for optical or for infrared wavelengths. Furthermore simulations of the electric field in the vicinity of the metal nanostructures were performed using the finite element method.