Precise tailoring of evaporated gold nanocones using electron beam lithography and lift-off

The ability to fabricate nanocones with precise dimensions is essential for several emerging applications. We demonstrate here a method which can be used to fabricate arrays of gold nanocones with high dimensional precision using lithographic and lift-off means. electron beam (ebeam) writing of a spin-coated PMMA-based bilayer resist deposited onto silicon wafers is used to form a shadow mask. This mask gradually closes as the deposition of gold (using ebeam evaporation) proceeds-the result is arrays of gold nanocones on the silicon wafer surface after lift-off of the resist. Observations using scanning electron microscopy enable a statistical study of the dimensions of 360 gold nanocones-the results demonstrate the high precision of the nanocones dimensions. The fabrication process enables the creation of arrays of nanocones with a base diameter varying from 53.6 ± 2.1 nm to 94.1 ± 2.4 nm, a vertical height ranging from 71.3 ± 4.1 nm to 153.4 ± 3.4 nm, and an apex radius of curvature ranging from 8.4 ± 1.2 nm to 11.6 ± 1.5 nm. The results are compared with the predictions of a deposition model which considers the evolving shadow masking during the gold deposition to compute the nanocone profile.