After chemical mechanical planarization (CMP) processes, copper microcorrosion was found in a specific pattern, which consisted of two sides of small trench islands connected by a long underlayer metal line. The depth of the copper recess was strongly dependent on the length of the underlayer metal line as well as the size of the trench islands. This phenomenon was different from typical photocorrosion; it was suggested to be induced by the additional electrochemical potential from the connection of the trench islands. Auger analysis proves that higher copper oxidation rate occurred on the specific pattern compared to those without connection. In addition, the pattern-dependent microcorrosion was identified by blocking the connection of the trench islands. A proposed model was given to account for the enhanced copper corrosion from the specific patterns during CMP. (C) 2004 The Electrochemical Society.