Exploiting the third dimension in nanofabrication technology with scanned high energy ion beams

Abstract

Focussed ion beam techniques are powerful tools to fabricate and obtain images of nanostructures. Here we propose to study and create nanostructures by implantation of focussed high energy heavy ions. For this purpose we are developing and building at the new 5MV tandem accelerator of the Universidad Autónoma de Madrid, a facility capable of delivering beams focussed to a diameter below 10nm that can be scanned over the sample. This contrasts with previous methods which use keV ions. As a consequence, structures with small lateral size and a much larger perpendicular size like patterns of columns, can be created. These are expected to allow a high packing density of functional units, and other specific advantages.The nanobeam will be used mainly to create nanostructures by irradiation with heavy ions with an energy of 20–50MeV in a precise pattern (ion beam lithography), since it takes only one or few ions per spot to create structural, electronic, magnetic or chemical changes in certain materials along the ions tracks and therefore, very low ion beam intensities can be applied. Structures like ordered conducting wires in insulating media or three-dimensional magnetic column structures in a diamagnetic medium can be created. The latter will be the first application of the facility, and could be developed to provide a data storage medium with Terabits/in.2 capability, drastically increasing the present storage density.The facility will also generate nanobeams of 2–10MeV protons. They will be used to develop a scanning transmission proton microscope for research of the mentioned nanostructures and the detection of defects, voids, precipitates, etc. in other thinned samples.