  Anodic aluminum oxide (AAO) or anodic alumina template containing hexagonally
ordered nanopores has been widely used over the last decade for the development
of numerous functional nanostructures such as nanoscale sensors, computing
networks and memories. The long range pore order requires the starting aluminum
surface to be extremely smooth. Electropolishing is the most commonly used
method for surface planarization prior to anodization. While prevalent, this
method has several limitations in terms of throughput, polishing area and
requirement of special experimental setups, which introduce additional speed
bottlenecks in the intrinsically slow AAO-based nanofabrication process. In
this work we report a new generation of the so-called "chemical polishing"
approach which circumvents these stumbling blocks in the pretreatment phase and
offers a viable, simpler, safer and faster alternative to electropolishing.
These benefits are obtained without sacrificing the quality of the final AAO
template. In this work we have (a) identified the optimum parameter regime for
chemical polishing and (b) determined process conditions for which a novel
parallel nanoridge configuration self-assembles and extends over a distance of
several microns. Such patterns can be used as a mask for fabricating
nanocrossbars, which are the main structural components in myriad nanoscale
memories and crosspoint architectures.
