Paper SS-TuP6
Pattern Formation through Leveled Copper Etching after Dysfunctional Electropolishing

Tuesday, November 1, 2011, 6:00 pm, Room East Exhibit Hall

Electropolishing is a common industrial practice whereby a metallic surface is subjected to an anodic potential in an appropriate electrolyte to produce a microscopically smooth surface. It is typically performed in concentrated acid with cell potentials ranging from between 1.3 and 2.3V. However, little research has been conducted in the parameter space outside the electropolishing regime. Previous research in our group using deviations from electropolishing conditions has characterized a wide range of fascinating surface structures including terraces, oxide nanotubes, stripes, and dimples. Our current work involves using the copper/phosphoric acid system as a model system to study deviations from electropolishing conditions and the resultant surface features.

Upon exposing copper substrates to a high applied cell potential in concentrated phosphoric acid, etched surface patterns up to over a micron in depth are observed. Characterization of the patterns includes the use of atomic force microscopy (AFM), scanning electron microscopy (SEM), and surface enhanced Raman spectroscopy (SERS). The surface patterns evolve with variation in temperature and phosphoric acid concentration. A distinguishing feature is that the patterns are etched into rather than grown upon the copper substrate, promoting mechanical stability. Additionally, the tops of the surface features are level with respect to their surroundings. Potential applications include electrodes, current collectors for lithium ion batteries, catalysts, micro-cooling, and substrates for the fabrication of other surface morphologies.