Nanopatterning Approach for Multiple-Height Metasurfaces with Absolute Lateral Spatial Precision

The ability to fabricate complex nanostructures with precise three-dimensional (3D) control provides a powerful degree of freedom for tailoring optical resonances and advancing photonic functionalities. Conventional lithographic approaches, such as deep ultraviolet (DUV) and electron beam lithography (EBL), offer high-resolution patterning in two dimensions. However, extending these approaches into the third dimension typically requires multiple lithography and alignment steps, resulting in cumulative lateral misalignment errors that fundamentally limit structural accuracy and device performance. Here, we present a fabrication strategy for all-dielectric nanostructures with multiple discrete height profiles that achieve absolute lateral alignment accuracy across layers. The method combines single-step lithography followed by reactive ion etching (RIE) and an on-demand, electrochemically controlled selective removal of metallic masks using atomic force microscopy (AFM). By the complete elimination of repeated alignment procedures inherent to multistep lithography, our approach ensures nanometer-scale registration precision between different height profiles. We experimentally demonstrate nanopillar arrays with three distinct height profiles fabricated over a 20 × 20 μm² area exhibiting no measurable lateral misalignment and showing tunable optical responses arising from the controlled height variations. This method thus establishes a robust route for fabricating truly 3D metasurfaces with deterministic spatial accuracy and enhanced optical functionality. Beyond metasurface engineering, this technique is broadly applicable to chiral nanophotonics, nanofluidics, high-density data storage, and biosensing, where stringent control of both height and in-plane alignment is essential for device performance.