Self-Organized Ordered Nanostructures by Ion Beam Sputtering

There is a high demand of lateral structures with dimensions from some nanometers to tens of nanometers in the fields of electronics, magnetic storage, and biology. This has triggered research activities in self-organization and self-assembling mechanisms for their fabrication which can successfully complement the classical methods of lithography. These self-organization processes, classified as “bottom-up” approaches, in contrast to the “top-down” approaches of lithography, will join more and more the nanotechnology.
In the series of self-organized processes for the fabrication of nanostructures the pattern formation during ion erosion of surfaces has attracted much interest in the last years. In the continuous sput-tering process, induced by the bombardment with low-energy ions, periodic surface patterns ap-pear in form of ripples under off-normal incidence or regular arrays of hexagonally ordered dots at normal incidence. The dimension of the patterns is related to the size of the typical collision cascade and lies in the range of ten to tens of nanometers, depending primary on ion energy, inci-dence angle, and surface temperature. The self-organization mechanism relies on the interplay between a surface instability caused by the sputtering and surface diffusion processes. Regular ripple and dot morphologies have been produced in this way on very different materials including semiconductors, and metals, demonstrating the universality of this mechanism.