Here we show a method for patterning a thin metal film using self-assembledblock-copolymer micelles monolayers as a template. The obtained metallic maskis transferred by reactive ion etching in silicon oxide, silicon and silicon nitridesubstrates, thus fabricating arrays of hexagonally packed nanopores with tunablediameters, interspacing and aspect ratios. This technology is compatible withintegration into a standard microtechnology sequence for wafer-scale fabrication ofultrathin silicon nitride nanoporous membranes with 80 nm mean pore diameter.