Published online by Cambridge University Press: 01 February 2011
Electromigration in upper M2 and lower M1 Cu lines in dual damascene interconnects was investigated by using two types of via terminated structures. Two different types of failures termed as abrupt and gradual failures were observed. Electromigration failures in M2 were mostly by gradual failures, while abrupt failures dominated in M1. Significantly different types of voids were observed in M1 as compared to those in M2, though similar resistance change was observed. Experimentally calculated activation energies for M1 and M2 indicated interfacial electromigration. Activation energy of M1 was found to be much lower than that of M2. This clearly demonstrates the asymmetry of electromigration in M2 and M1 Cu lines in dual damascene interconnects.