The Focused Ion Beam (FIB) system uses a Ga+ ion beam to raster over the surface of a sample in a similar way as the electron beam in a scanning electron microscope (SEM). One of the capabilities of FIB is its ability to mill complex nanopatterns (including bitmapped images), making it the ideal tool for precise 3D maskless nanopatterning of a wide variety of materials. The FIB is the ideal tool for prototyping a wide range of devices in the R&D stage of product development, since it offers high reproducibility and scalable throughput. However, the ion bombardment of the specimen surface can introduce various artifacts, such as surface amorphization, Ga+ ion implantation, cratering and material re-deposition.
Electron-beam lithography is an alternative tool for 3D nanopatterning. E-Beam lithography uses a focused beam of electrons to “write” patterns on a surface covered with an electron sensitive film (resist). The main advantage of electron-beam lithography is that it can direct-write with nm resolution. This form of maskless lithography has high resolution and low throughput.
These two techniques are considered to be the best methods for fabricating structures for surface plasmon coupling and manipulation. The structures can be used to obtain confined longitudinally polarized plasmonic focal spots and other higher order effects.
In this study, we present a comparison between FIB nanopatterning and E-beam lithography to fabricate various nano engraved plasmonic structures in gold comprising different spiral types and their engagements.