Comparison of electromigration in Cu interconnects with atomic-layer- or physical-vapor-deposited TaN liners

Electromigration in 0.07 μm wide Cu interconnections has been investigated for sample temperatures from 213 to 300°C. The effect of atomic-layer- or physical-vapor-deposited TaNx and physical-vapor-deposited Ta liner layers in Cu damascene lines on electromigration was also studied. A lower lifetime and activation energy for electromigration was observed in tested lines with sidewall voids. Similar electromigration lifetime and activation energy observed from samples with either atomic-layer- or physical-vapor- deposited TaNx suggested that the dominant diffusion paths in the Cu lines were not sensitive to the TaNx layer and were along the Cu/dielectric interface and/or grain boundaries. © 2007 The Electrochemical Society.