Extending the working distance in near-field lithography with a two-material topological photonic crystal

Near-field lithography has proven effective for fabricating large-area periodic patterns. However, achieving a substantial working distance (WD) remains a persistent challenge. This work presents an approach utilizing a one-dimensional (1D) topological photonic crystal (TPC) comprising two distinct dielectric materials. The TPC exhibits topologically non-trivial states, which enhances its tolerance to film layer thickness variations, with a demonstrated range of ±3<i>n</i><i>m</i>. Simulations demonstrate that incorporating this TPC extends the WD to 100 nm, enabling the fabrication of super-resolution patterns with a 65 nm half-pitch in the photoresist. Furthermore, the structure efficiently transmits second-order diffracted light, simplifying mask preparation. Compared to conventional photonic crystals (PCs), this two-material TPC offers simplified fabrication, greater tolerance to fabrication tolerance, and improved performance in near-field lithography, making it a promising candidate for advanced lithographic applications.