Hierarchical silicon nanostructured arrays via metal-assisted chemical etching

Hierarchically arranged nanostructures, configured in both nanopillars and nanoholes, have been fabricated via a low-cost approach that combines metal-assisted chemical etching (MaCE), nanosphere lithography and conventional photolithography. By manipulating the catalyst morphology as well as the deposition method, different interesting nanostructures like nanowalls and nanograsses were fabricated at the galleries among the nanopillar blocks. Using a similar strategy, hierarchical negative structures (nanoholes) have also been successfully demonstrated. The successful construction of these diversified hierarchical nanostructures illustrates that MaCE could be employed as a feasible, low-cost method for multi-scale silicon micro/nano machining, which is highly desirable for widespread applications, including tissue engineering, optoelectronics, photonic devices and lab-on-chip systems.