We have developed a simple fabrication process which allows the production of nanoscale silicon structures. Rough silver films are used as an etching mask for reactive ion etching at 10 °C. Variation of the etching parameters, such as the rf power, allows control over the shape of the features; the production of both pillars and cones is possible. The density and diameter of these features are controlled by the etching time. Pillars with diameters as small as 5 nm are reported. © 1999 American Institute of Physics.