Extensions of molecular ruler technology for nanoscale patterning

By combining optical lithography and chemical self-assembly, the authors circumvent the limitations of photolithography and provide a parallel, low-cost alternative to fabricate sub- 50 nm features. Self-assembled multilayers, composed of alternating layers of α,ω -mercaptoalkanoic acids and copper (II) ions ("molecular rulers"), are used as an organic sidewall spacer resist on initial lithographic structures enabling the precise, proximal placement of a secondary structure via lift-off. Here, the authors implemented a positive-tone bilayer resist for improved line-edge characteristics of the secondary structure and evaluated the lithographic and electrical performance of nanostructures fabricated using this approach. Additionally, they describe extensions of this technique by which planar nanojunctions were created, and the generated nanometer-scale pattern was transferred to the underlying substrate.