Three focused ion beam nanofabrication of plasmonic devices

Nanotechnology requires both characterisation methods, that can look at the nanoscale and monitor processes and a scale that is typically not accessible by optical techniques, and nanofabrication methods, that can modify the local surface structure and chemistry in a well-defined manner. In this contribution, we will show recent advantages in focussed ion beam lithography (FIB) utilizing three different ion beams, namely Helium, Neon and Gallium and particularly their combination. In FIB the surface is modified through sputtering and no mask or resist is required. In contrast to electron beams at similar beam energies, ion beams travel in a much straighter fashion and allow e.g. the fabrication of high-aspect ratio structures. While relatively large structures (100 x 100 µm2) can be fabricated in reasonable time using Gallium ions, Neon and Helium ions allow very precise structuring of individual objects and polishing of structures and surfaces. We could show, that latter aspect is relevant to fabricate smooth and effective plasmonic waveguides and circuit elements.