Achieving narrow gaps in micro-nano structures fabricated by maskless optical projection lithography

We propose a strategy to achieve narrow gaps in micro-nano structures by femtosecond (fs) laser maskless optical projection lithography (MOPL) technique. The simulation predicts the trend of each factor affecting the gap width, which agrees with the experimental result. A narrow gap of 243 nm is obtained by optimizing the structure design and processing parameters. Furthermore, large-area functional micro-nano structures with narrow gaps are fabricated. The strategy of optimizing the width of narrow gaps in MOPL is flexible and effective, providing wide application prospects in the fabrication of micro-nano devices in nanophotonics and semiconductors.