Copper nanopattern on SiO2 from sputter etching a Cu∕SiO2 interface

We have observed a Cu nanostructure self-assembled on a SiO2 substrate during ion beam etching the Cu∕SiO2 interface. We have deposited a thin Cu layer on a glass substrate and etched the deposited layer by a neutralized argon ion beam. At the stage when almost all metal is removed by etching, we have observed an ∼20‐nm-sized Cu pattern on the substrate. By atomistic Monte Carlo simulations we have demonstrated that during sputter etching, a morphology self-organizes on the surface of the Cu layer whose size and shape matches the observed Cu nanostructure. We conclude that the observed Cu nanopattern on the substrate results from the surface morphology developed by sputter instability during etching of the deposited layer.