Fabrication of site-controlled tunnel pits with high aspect ratios by Electrochemical etching of Al using masking film

The process for the site-controlled formation of tunnel pits with high aspect ratios by anode etching of Al (100) foil is described. Introduction of a small amount of Cu on the Al foil, which has a patterned thin layer of polymers, initiated the uniform development of pits and generated the tunnel pits with sufficiently high aspect ratios. The obtained ordered array of tunnel pits with high aspect ratios will be used for the preparation of several types of functional devices in addition to the improvement of electrolytic capacitors, which use the Al foil with tunnel pits as a surface-enlarged electrode. (C) 2007 The Electrochemical Society.