Resistivity reduction by external oxidation of Cu–Mn alloy films for semiconductor interconnect application

A self-forming barrier process using Cu–Mn alloy has been reported to exhibit excellent reliability for interconnect lines in advanced semiconductor devices. However, Mn increases resistivity. In this work, the authors investigated optimum annealing conditions to remove Mn from the Cu–Mn alloy by forming an external Mn oxide and to reduce resistivity to a level of pure Cu. The results were interpreted by an external oxidation mechanism of Mn atoms.