C-shaped electron beams: design, experimental production and application

The development of metamaterials operating at visible light wavelengths requires metamaterials to be produced with nanoscale structure over large areas. Improvements in the efficiency of electron beam lithography (EBL) could play an important role in accelerating this development. In this paper we show the production of a shaped probe for use in EBL. A phase structured electron wave containing vortices can be focused to produce a C-shaped cross section. Local spatial frequency analysis shows that both the gap and overall size of the C-shape can be easily controlled. We present the generation of such a C-shaped electron beam using a holographic binary amplitude diffraction mask. Thin AlF 3 film is exposed to the C-shaped diffraction order and demonstrates the facile production of both a metallic C-shaped structure as well as the etching of a C-shaped hole.