Electromigration Reliability of Dual-Damascene Cu/Oxide Interconnects

Abstract

AbstractAn electromigration study has determined the lifetime characteristics and failure mode of dual-damascene Cu/oxide interconnects at temperatures ranging between 200 and 325 °C at a current density of 1.0 MA/cm2. A novel test structure design is used which incorporates a repeated chain of “Blech-type” line elements. The large interconnect ensemble permits a statistical approach to addressing interconnect reliability issues using typical failure analysis tools such as focused ion beam imaging. The larger sample size of the test structure thus enables efficient identification of “early failure” or extrinsic modes of interconnect failure associated with process development. The analysis so far indicates that two major damage modes are observable: (1) via-voiding and (2) voiding within the damascene trench.