Defect and electromigration characterization of a two level copper interconnect

The effect of annealing conditions on defects and post CMP grain size in electroplated Cu lines is discussed. We have studied the effect of these parameters on interconnect reliability by measuring the electromigration of 'via-fed' structures. A failure criterion of 2% change in initial resistance was used for EM rather than the traditional 20% used for aluminum interconnect. The electromigration behavior of furnace annealed films is compared to rapid thermal annealed films and the activation energy is found to be in the range of 0.9 to 1.0 eV.