Fabrication of hexagonally ordered nanopores in anodic alumina: An alternative pretreatment

TL;DR

This paper introduces a new chemical polishing method for preparing aluminum surfaces to create highly ordered nanopores in anodic alumina, offering a faster, simpler, and safer alternative to traditional electropolishing without compromising template quality.

Contribution

The study develops and optimizes a chemical polishing process that improves nanopore ordering in anodic alumina, enabling scalable and efficient nanostructure fabrication.

Findings

Chemical polishing achieves comparable pore order to electropolishing.

Optimized parameters enable formation of self-assembled nanoridge patterns.

Process allows for scalable, high-quality nanostructure templates.

Abstract

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.