UCLA

Nanolithography is a critical step in the patterning and fabrication process of sub-micron and nanoscale structures, which can be integrated into electronic, optical, and biomedical devices for improved performance, sensitivity, and efficiency. State-of-the-art methods for advanced high-resolution lithographic techniques (e.g., extreme ultraviolet photolithography, electron-beam lithography) are limited by high equipment costs and/or time-consuming serial writing processes. I have focused on developing hybrid nanolithographic techniques with high throughput, low cost, and large scale, for patterning and fabrication of one-, two-, and three-dimensional (1D-3D) sub-micron and nanoscale structures that can be used for emerging applications.As a novel soft lithographic method, chemical lift-off lithography (CLL) was developed for high-throughput and wafer-scale nanopatterning. To lower the cost and improve the accessibility of CLL, we used commercially available digital versatile discs (DVDs) as templates to prepare elastomeric stamps for nanopatterning. Combined with thin-film etching and material sputtering, CLL was used to fabricate ultrathin 1D In2O3 nanoribbons to assemble field-effect-transistor (FET) biosensors. Integrated with a double-patterning strategy, CLL was used to pattern 2D gold nanodisks, which provided a new opportunity for photothermal intracellular delivery. Combined with material deposition and silicon etching, nanosphere lithography (NSL) was used to fabricate various 2D and 3D silicon nanostructures with high periodicity and structural integrity. We developed a strategy that combined NSL with silicon anisotropic etching, for scalable fabrication of ordered nanopyramid structures. This strategy, with adaptability and expansibility, provides theoretical guidance for the design and fabrication of periodic perovskite nanoarrays with enhanced light absorption and photoelectric sensitivity for high-performance photodetectors. To improve the resolution limit and to build on the practicality of conventional photolithography, we developed a derivative of conventional photolithography, dual-layer photolithography (DLPL), for nanoscale patterning. Utilizing the photoresponsivity variation of positive and negative photoresists, DLPL enabled patterning “outline-like” features (~180 nm) 25 times smaller than the photomask feature size (5 �m) with a single exposure. Combined with material deposition and silicon etching, DLPL can be used to fabricate 3D nanostructures for applications in electronics and biology.