Fabrication and characterization of squama-shape micro/nano multi-scale silicon material

This paper presents the fabrication of squama-shape micro/nano multi-scale structures and the analysis of the interaction among different-scale structures during the fabrication processes. Well-designed microstructures made of inverted pyramids and V-shape grooves are fabricated by KOH wet etching. High-dense high-aspect-ratio （HAR） nanostructures are fabricated atop microstructures by an improved maskless deep reactive ion etching （DRIE） process, with an optimized recipe to form mi- cro/nano dual-scale structures （MNDS）. Due to the impact of the profile of microstructures on the shape of nanostructures, dissymmetrical （i.e., squama-shape） nanopillars have been formed on the inclined surfaces of microstructures, while the sym- metrical nanopillars are formed on the horizontal surfaces with different formation velocities. Furthermore, the optical proper- ties of MNDS are not sensitive to structural parameters of microstructures, making the sample overcome the lithography limi- tation of conventional processes for photo-devices. Eventually, three-level structures are fabricated by sputtering a gold thin film on the MNDS, and the profile of MNDS is selective in the deposition of gold particles, which is very useful for practical applications.