Effects of failure criteria on the lifetime distribution of dual-damascene Cu line/via on W

The electromigration lifetime of a dual-damascene Cu line, where a W lower level line was connected to it, was investigated. The samples were tested using different failure criteria which was based on increase in test line resistance. It was observed that the lifetime distribution with failure criteria of 1% resistance increase was trimodal, while it was bimodal for a failure criteria of 50%. The three different types of observed deviant line resistance behaviors included plateau, fluctuation and uphill.