Prediction of transmission line lifetimes over temperature and current density

Transmission line test structures are stressed at ambient temperatures ranging from 75 to 160 °C and current densities from ∼5 to 7 MA/cm2. Failure is considered to have occurred when the resistance increases by 10% over its initial value. Failure times are modeled using Black’s equation and the Ea and current density exponent ‘n’ are found to be ∼1 eV and ∼2–4, respectively, in agreement with the literature. Predicted FIT rates are found to be negligible easily meeting even the most severe FIT budget. Experimental evidence suggests that the current density used in testing is well above the critical Blech value. Predicted lifetimes at J = 2.3 MA/cm2 are consistent with observation, indicating that high stress data can be used to predict low stress behavior.