Grating-assisted generation of 2D surface plasmon interference patterns for nanoscale photolithography

Generation of 2D surface plasmon interference patterns using a 3D metal-dielectric diffraction structure is studied. The potential application field is surface plasmon interference nanolithography aimed at fabrication of 3D periodic structures. The considered structure consists of a 3D dielectric diffraction grating with a metal film applied in the substrate region. The diffraction grating is designed to transform the incident wave into a set of surface plasmons that generate 2D interference pattern underneath the metal film. The configuration of the interference patterns is analyzed theoretically. It is shown by simulations within the rigorous electromagnetic theory that high-contrast interference patterns with the period 2.5–3.5 times smaller than the incident wave length can be produced. The configuration of the calculated patterns coincides with theoretically estimated ones. At the interference maxima electric field intensity exceeds incident wave intensity by an order of magnitude. The ways to control the form and period of the interference pattern by changing polarization and length of the incident wave are presented.