Evaluation of constant voltage testing for electromigration study

Constant voltage electromigration testing (CV) was evaluated to be a complementary method to traditional constant current (CC) testing during electromigration (EM) qualification. It is demonstrated that the EM lifetime in copper conductors could vary depending on the details of the circuit. There is also a difference in failure distribution and possibly in failure modes as well. Furthermore, the constant voltage test was used to probe the lifetime dependency on location and for investigating redundancy. The experiments showed non negligible differences in both types of test and it is concluded that further failure analysis required for confirming and/or understanding the differences in the observations.