Formation and interaction of micro/nano multi-scale structures

This paper presents the fabrication of squama-shape micro/nano multi-scale structures and the analysis of the interaction among different scale structures during fabrication processes. Well-designed microstructures made of inverted pyramids and V-shape grooves are fabricated by KOH wet etching. High-dense high-aspect-ratio nanostructures are realized atop microstructures by an improved maskless deep reactive ion etching (DRIE) process to form micro/nano dual-scale structures (MNDS). Due to the impact of the profile of microstructure on the shape of nanostructure, dissymmetrical (i.e. squama-shape) nanopillars have been formed atop inclined surfaces of microstructures, while symmetrical nanopillars are formed atop horizontal surfaces with different formation velocity. Furthermore, the optical properties of MNDS are not sensitive to structural parameters of microstructures, which makes it more tolerant to process errors and overcomes the lithography limitation of conventional processes for photo-devices. Additionally, three-level structures are fabricated by sputtering gold particles on MNDS, and the profile of MNDS is selective in the deposition of gold.