Macro and quasi-mesoporous silicon by self-assembling and metal assisted etching

The combination of two recent techniques developed in the last years demonstrates the possibility to obtain regular and semi- ordered macro and mesopores on any type of silicon substrates and with holes diameter ranging from 800 to 60 nm and less. Self-assembling of polystyrene nanospheres (PSNS) is obtained by floating technique, then the 2D crystal is lifted on a silicon substrate with a 30 nm silver thin film deposited by thermal evaporation or sputtering. The nanospheres are then reduced in diameter by reactive ion etching (RIE) in oxygen plasma, then the samples are exposed to Ar ions sputter-etching (SE) for thin film structuration. At this point of the process the polystyrene nanosphere mask is removed and a metal assisted etching (MAE) of few minutes is performed. Ordered and regular pores of diameters ranging from 500 to 60 nm have been obtained.