Hierarchical Lithography for Generating Molecular Testbeds

Progress in molecular optoelectronic sensor development requires the production of nanostructures, which control the orientation and presentation of individual molecular species. Indeed, the prospect of producing nanochips with several different molecular sensors surface mounted on a 100 nm × 100 nm chip is clearly realizable. In order to gain the greatest advantage from this miniaturization, ordering, in the form of indexed localization of these nanostructures, is also required. It is unlikely that any one lithographic method will prove satisfactory for pattern production at the multiple size scales currently targeted for sensor integration. This paper targets the context of the device prototype development laboratory, where direct write methods may not be available or optimal. Two different, accessible types of lithography, with overlapping ranges of resolution, are used to create the multiple size scale levels of patterning required for the generation of testbeds for single molecule studies. Digital optical projection lithography provides for fast prototyping and large scale indexing features from the macro scale to the ~5 ¿m scale. The intermediate scale, from 10 ¿ m to 100 nm is addressed using phase-shift lithography. These combined techniques provide indexing at a resolution compatible with addressing individual molecular lithography structures, particularly DNA origami, which in turn can be used to localize species in the 100 to ~10 nm range.