Ion-beam sculpting at nanometre length scales

Manipulating matter at the nanometre scale is important for many electronic , chemical and biological advances(1-3), but present solid-state fabricatio n methods do not reproducibly achieve dimensional control at the nanometre scale. Here we report a means of fashioning matter at these dimensions that uses low-energy ion beams and reveals surprising atomic transport phenomen a that occur in a variety of materials and geometries. The method is implem ented in a feedback-controlled sputtering system that provides fine control over ion beam exposure and sample temperature. We call the method "ion-bea m sculpting'', and apply it to the problem of fabricating a molecular-scale hole, or nanopore, in a thin insulating solid-state membrane. Such pores c an serve to localize molecular-scale electrical junctions and switches(4-6) and function as masks(7) to create other small-scale structures. Nanopores also function as membrane channels in all living systems, where they serve as extremely sensitive electro-mechanical devices that regulate electric p otential, ionic flow, and molecular transport across cellular membranes(8). We show that ion-beam sculpting can be used to fashion an analogous solid- state device: a robust electronic detector consisting of a single nanopore in a Si3N4 membrane, capable of registering single DNA molecules in aqueous solution.