Nanoimprint lithography (NIL) is challenging extreme-ultraviolet lithography for the 32 nm mode and beyond (see www.laserfocusworld.com/articles/334919). But the resolution of NIL is itself limited by the quartz templates used for replicating features on a substrate. Quartz templates are typically fabricated using electron-beam lithography (EBL), which is an expensive serial process. Alternatives, such as dip-pen nanolithography and other superlattice- and carbon-nanotube-based approaches, have shortcomings in resolution or in creating complex patterns over large areas. In contrast, a hybrid molecular-ruler approach developed at Pennsylvania State University (University Park, PA) achieves sub-30 nm patterning over a full wafer.
In molecular-ruler nanolithography, addition, patterning, and then removal of multilayer thin films creates metallic nanostructures at molecular length scales. Here, EBL or other methods create the first level of metallic features. Then, alternating layers of molecular-ruler materials bind to this structure. A daughter metallic structure is added and then the overall structure is etched to create nanogaps with the same thickness as the molecular-ruler layers. A final etching process transfers the metallic pattern into the quartz substrate. Contact Mark W. Horn at [email protected].