A simple, reproducible process for preparing highly textured silicon surfaces, so-called black silicon (bSi), is described. First, a fine-grained natural mask is deposited by using a CF 4 /O 2 plasma in combination with an Al 2 O 3 cathode. SEM and AFM investigations demonstrate the variation of grain diameter and density with power density and process duration. The pattern of this mask is transferred into the silicon substrate by reactive ion etching in a Cl 2 /Ar plasma. This process yields a high density of Si nanowires (10 2 – 10 3 μm −2 ) with diameters smaller than 20 nm and aspect ratios up to 20. Finally, the size of these nanowires is further reduced to less than 10 nm by rapid thermal oxidation.