ABSTRACT
Nanopatterning of metallic thin films is becoming increasingly important due to recent developments in nanoelectronics and nanophotonics. There are important applications of such techniques
in spintronics [1] and plasmonics [2], where information is stored and/or transferred by using nanoscale metallic elements. Such structures are usually fabricated by electron beam lithography while patterning by FIB is a much less frequent technique even though it possesses a lot of advantages, especially in research and rapid prototyping applications [3,4]. The main advantage of this method compared to usual lithography techniques is speed and simplicity of the maskless one-step process based on direct ion-beam writing, i.e., transferring a pattern by direct impingement of the FIB onto the sample. FIB direct writing can combine a series of techniques such as milling, implantation, ion-induced deposition (see Fig. 11.5), and ion-assisted etching. The main drawback in the patterning of nanostructures from metallic thin films by FIB milling is residual roughness, which is also transferred onto the edges of milled patterns and limits the quality and resolution of fabricated nanostructures. The key issue in nanofabrication by FIB is a proper choice of ion beam parameters such as ion beam current and its profile (spot size), scan routine, and speed over the sample, among others.
