Localized electrochemical deposition and dissolution of Cu on microstructured Ti surfaces

Abstract

Local processes of electrochemical deposition and dissolution of Cu on microstructured Ti substrates were studied using cyclic voltammetry, scanning Auger microscopy (SAM) and in situ optical microscopy. Microstructures with different chemical and physical properties were prepared by various methods. As a first approach TiN-microareas with metallic conductivity behavior in a n-type semiconducting TiO 2-matrix were obtained on Ti(0001) single crystal surfaces using a photoresist technique combined with N + 2-implantation and subsequent electrochemical oxidation. In a second approach, microstructures such as pits and trenches were produced by laser induced local dissolution of a TiO 2-film formed electrochemically on a polycrystalline Ti substrate. Electrodeposition studies showed that on TiN-microareas the bulk Cu deposition starts at significantly lower cathodic overpotential (∣ η∣<50 mV) than on surrounding TiO 2-domains. A deposition on the entire TiN/TiO 2-surface can be achieved applying cathodic overpotentials higher than 220 mV. At relatively low cathodic overpotentials the electrodeposition reaction on laser microstructured TiO 2-surfaces was found to occur only at pits and trenches. Studies of metal dissolution processes showed that Cu deposits cannot be removed anodically from TiO 2-surfaces reflecting the semiconductor properties of TiO 2. Thus, in the case of a Cu-covered TiN/TiO 2-microstructured surface a local anodic dissolution of the deposit can be achieved only at TiN-microareas. Possible applications of experimental results for preparation of heterostructures by localized electrochemical deposition and dissolution of metals are discussed.