Realizing Square-Ordered\nNanopillars with a 0.1-Tera-Density\nthrough a Superimposed Masking Strategy for Advanced Surface-Enhanced\nRaman Spectroscopy

Despite widespread interest in nanoscale pillar structures\nfor\nvarious optical devices, including solar cells, photonic crystal lasers,\nand sensors, the critical challenges for mass production are the high\nequipment costs and limited scalability of traditional manufacturing\nmethods. To overcome these hurdles, this study develops a simple and\nhighly scalable etch-mask superposition technique based on thermally\nassisted nanotransfer printing (T-nTP) of Cr line patterns. The orthogonal\nsuperposition of linear Cr mask patterns creates double-height cross-point\narrays that effectively and selectively protect the underlying SiO<sub>2</sub> during subsequent reactive ion etching. This process generates\nhighly uniform nanoscale pillar arrays with an extremely high density\nof 0.1 tera-pillars per square inch, eliminating the need for high-cost\npatterning platforms. As an exemplary application, we demonstrate\nthe use of these perfectly ordered nanopillar arrays as high-performance\nsurface-enhanced Raman scattering (SERS) sensors through the deposition\nof noble metal films on the nanopillar surface. These nanopillars\nenable exceptionally uniform SERS intensity with spot variations of\nless than 7% in methylene blue (MB) measurements. Additionally, they\nexhibit sensitive detections and accurate quantification for thiabendazole\n(TBZ) at concentrations as low as 10<sup>–8</sup> M, along\nwith multicycle reusability without noticeable degradation, owing\nto the outstanding robustness of the SiO<sub>2</sub> nanopillars.