Helium focused ion beam irradiation with subsequent chemical etching for the fabrication of nanostructures

In this paper we demonstrate a nanofabrication technique based on local ion irradiation of silicon dioxide with a focused helium ion beam. The wet etching of silicon dioxide irradiated with a focused helium ion beam is described in a two-dimensional case both numerically and experimentally. We suggest a model for the etching process based on the distribution of ion induced defects in the irradiated material. The profile of the surface of the etched silicon dioxide is simulated and compared with the results from scanning electron microscopy. Fabrication of a suspended nanostring with a diameter of less than 20 nm by means of etching ion-irradiated material is demonstrated.