Patterning Disorder in Monolayer Resists for the Fabrication of Sub-100-nm Structures in Silver, Gold, Silicon, and Aluminum

This paper describes the development of a new methodology, "topographically directed etching" or TODE, that relies on patterned regions of disorder in SAMs to generate features specifically at the edges of topographically patterned metal films. The features that are produced have lateral dimensions of <50 to 200 nm and are at least an order of magnitude smaller than those patterned originally in the material, when the original patterning is at the scale of μm. Several variations of this methodology are described, the results of which include the generation of 100-nm trenches in silver, gold, SiO2/Si, and Al2O3/Al, 100-nm lines of silver, asymmetric structures in aluminum and silver, and 50-nm features in curved silver surfaces. Although the techniques can be combined with photolithography, the pattern transfer step is based on chemical reaction and is therefore not limited by diffraction or depth of focus. This methodology makes the fabrication of ∼100-nm structures accessible to chemists/materials scientists without access to tools required for electron-beam writing and other procedures of nanofabrication.