Three-dimensional periodic silicon-based nanostructures have shown unique optical, electrical, and mechanical properties, however these types of structures remain difficult to fabricate in a facile manner. Nanosphere lithography is a simple, high-throughput technique to form large-area, close-packed monolayer arrays of nanospheres. These arrays can be directly used as etching masks to generate silicon-based nanostructures. Typically, the nanostructures produced are created by single etches of the nanosphere array mask. Here, we report multiple patterning nanosphere lithography, which enables size tuning of the nanostructures in three dimensions utilizing the nanospheres for multilayer masking throughout multiple rounds of etching. By exploiting the degradable nature of polystyrene during reactive ion etching, we have fabricated large-area three-dimensional periodic silicon nanostructures. These hierarchical nanostructures can be tailored to be tiered with independent tunability in height and diameter at each level. More complex tube structures have also been produced by combining metal deposition with subsequent reactive ion etching. Research is underway to investigate these silicon nanostructures as templates for periodic plasmonic nanostructures in three dimensions as well as for non-viral transfection for gene editing in cancer immunotherapy.

Multiple-patterning nanosphere lithography for periodic 3D hierarchical nanostructures

254th National Meeting (2017)

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