Physiochemical Coupled Dynamic Nanosphere Lithography Enabling Multiple Metastructures from Single Mask.

Metastructures are widely used in photonic devices, energy conversion and biomedical applications. However, to fabricate multiple patterns continuously in single etching protocol with highly tunable photonic properties is challenging. Here we proposed a simple and robust dynamic nanosphere lithography by inserting a spacer between the nanosphere assembly and the wafer. The nanosphere diameter decrease and uneven penetration of the spacer during etching leads to a dynamic masking process. Coupled anisotropic physical ion sputtering and ricocheting with isotropic chemical radical etching achieved highly tunable structures with various 3D patterns continuously forming through a single etching process. Specifically, the nanosphere diameters define the periodicity, the etched spacer forms the upper parts, and the wafer forms the lower parts. Each part of the structure is highly tunable through changing nanosphere diameter, spacer thickness and etch conditions. Using this protocol, we realized numerous structures of varying sizes including nano mushrooms, nanocones, nano pencils, and nanoneedles with diverse shapes as proof of concepts. The broadband antireflection ability of the nanostructures and their use in SERS were also demonstrated for practical application. Our method substantially simplified the fabrication procedure of various metastructures, paving the way for its application in multiple disciplines especially in photonic devices. This article is protected by copyright. All rights reserved.