Electromigration Failure Mechanism and Lifetime Expectation for Bi-Modal Distribution in Cu/Low-k Interconnect

The root cause and an approach to lifetime expectation of bi-modal distribution in Cu/low-k interconnect have been elucidated through experimental and simulation results. The early mode with short failure time and voids at via bottom interface, could be explained by pre-existing voids and large current density resulting from gouging via bottom profile. A high compressive SiCN making Cu/SiCN interface near via into tensile stress causes void nucleation in its specified sites, which indicate the late mode. And component lifetime can be predicted using the data obtained only from early failure, because of the same in activation energy and acceleration factor. This comprehension for bi-modal behavior is helpful in EM reliability of technology node beyond 45 nm.