A study of bimodal distributions of time-to-failure of copper via electromigration

Bimodal distributions of time-to-failure (TTF) were often seen in copper via electromigration (EM) tests. The failure mechanism of the stressed samples could be correlated to time-to-failure of the EM test. Early-failures were via-related, whereas late-failures were metal-stripe-related. The failure mechanisms are discussed.