Constant voltage electromigration testing

Constant voltage electromigration was investigated as a method for assessing reliability in narrow Cu conductors. It is demonstrated theoretically that constant voltage (CV) testing can offer advantages over constant current (CC) testing for material that may vary significantly in geometry (thickness or line width) from sample to sample. Using known misprocessed material, this anticipated result was confirmed. Experiments with material that was properly produced showed that the advantages of CV over CC were minimal, but the values of the median time to failure and the lognormal standard deviation of the CC and CV stressed material agreed quite well. A potential difference in the failure distribution was observed, but needs to be confirmed.