Size and shape control of a variety of metallic nanostructures using tilted, rotating evaporation and lithographic lift-off techniques

Here, we demonstrate a simple top-down method for nanotechnology whereby electron beam (ebeam) lithography can be combined with tilted, rotated thermal evaporation to control the topography and size of an assortment of metallic objects at the nanometre scale. In order to do this, the evaporation tilt angle is varied between 1 and 24°. The technique allows the 3-dimensional tailoring of a range of metallic object shapes from sharp, flat bottomed spikes to hollow cylinders and rings—all of which have rotational symmetry and whose critical dimensions are much smaller than the lithographic feature size. The lithographic feature size is varied from 400 nm down to 40 nm. The nanostructures are characterized using electron microscopy techniques—the specific shape can be predicted using topographic modelling of the deposition. Although individual nanostructures are studied here, the idea can easily be extended to fabricate arrays for e.g. photonics and metamaterials. Being a generic technique—depending on easily controlled lithographic and evaporation parameters—it can be readily incorporated into any standard planar process and could be adapted to suit other thin-film materials deposited using physical means.