Various technical issues related to feature scaling and recent electrochemical technologies advances for on-chip copper interconnects at Intel are reviewed. Effects of additives on electroplating, as well as performance of novel Cu direct plating on ruthenium liner are discussed. An electroless cobalt capping layer of Cu lines, which led to increased electromigration resistance, has been characterized. The potential application of carbon nanotubes as future interconnects materials, their properties and controlled placement by using dielectrophoresis are also reviewed. (c) 2006 Elsevier Ltd. All rights reserved.