Fabrication of silicon hierarchical nanopillar arrays based on nanosphere lithography

A fabrication process of silicon hierarchical nanopillar arrays (NPAs) based on the self-assembled colloid particle monolayer is presented. Using colloid particles assembled by the evaporation-induced method as masks, well-ordered silicon NPAs were fabricated by assessing the deep reactive ion etching process. After the optimisation of the cycles of etching and passivation steps, double-layer hierarchical NPAs were achieved simultaneously. Systematic analysis and experiments were conducted to investigate the transition from well-ordered silicon NPAs to silicon hierarchical NPAs. An explanation of this transition is provided based on the collapsing phenomenon discovered in the experiments.