Ultraprecision and highly uniform nanoscale conformality enabled by introducing oxide buffer layer for one-dimensional grating standard

One-dimensional nano-grating standard (ODNGS) is widely recognized as a crucial nanometric standard for metrological technology. However, achieving the ultratiny size of ODNGS with high consistent uniformity and low roughness by conventional processes such as the inductively coupled plasma (ICP) etching method presents a significant challenge in obtaining accurate calibration values. In this work, a 50-nm ODNGS with a conformal buffer layer (Al₂O₃) is successfully obtained, indicating outstanding stability and abrasion resistance. Remarkably, the introduction of hydrogen silsesquioxane (HSQ) and amorphous Al₂O₃ simultaneously guarantees an incredibly small expanded uncertainty (0.5 nm) and repeatability of the standard uniformity (less than 0.3 nm) in the grating dimensions. The I-V curves of ODNGS with an Al₂O₃ buffer layer at room temperature (RT) and 200 °C are depicted respectively to showcase the sustained favorable insulation properties. Notably, the nanostructure fluctuation, line edge roughness (LER) and line width roughness (LWR) of the standard can be decreased obviously by 64.1%, 63% and 70%, respectively. Our results suggest that the ODNGS with Al₂O₃ exhibits exceptional precision and robust calibration reliability for calibrating nanoscale measuring instruments. It holds tremendous potential for manufacturing high-precision nanostructures and grating arrays with precisely controllable dimensions, which will play a pivotal role in the fabrication of microfluidics chips, metasurface and photodetectors in the future.