Fabrication of Sub-10 nm Metallic Structures via Nanomasking Technique for Plasmonic Enhancement Applications

One area of nanoscience that has become popular in recent years is the study of optics at the nanoscale. Due to enhanced fabrication techniques, new geometries and improved dimensional resolutions have been allowing the creation of nanostructures for use in this area. Nanoscale geometries cause unique optical effects such as enhancement of the signal’s electric field strength at the surface of a substrate. Specifically, structures separated by nanogaps (10 nm and smaller) have been shown to exhibit strong field enhancement within the gaps. This has opened up the potential for surface enhanced spectroscopies, enhanced absorption for photovoltaics, and improved sensing and detection technologies. This work discusses a new fabrication technique to create nanostructures and nanogaps below the resolution limit of the lithography system used, down to sub-10 nm dimensions. This involves a sacrificial mask, and thus has been dubbed the “nanomasking” technique. This technique increases the previously demonstrated capabilities by enabling fabrication of many nanogaps that are below the resolution limit of the lithography system over a wafer-scale area. It also provides the unique ability to create sub-lithography limited nanostructures both with and without adjacent nanogaps. Various geometries have been fabricated using the technique, demonstrating its versatility. Results show promise for the possibility of using nanomasking to create optical enhancement devices. The broad range of fabrication capabilities of the technique may allow it to be useful in many other areas of nanotechnology as well. It makes it easier to fabricate nanostructures across a greater surface area. This is crucial for newly developed nanofabrication methods if they are to benefit future technology or manufacturing processes