A Versatile, Via Terminated Electromigration Test Structure for Various Stress Modes Used During Fast Wafer Level Reliability (fWLR) Testing

摘要

A multipurpose electromigration (EM) test structure designed for advanced fast wafer level reliability (WLR) tests is described in this work. It is shown that different failure location and failure modes can be detected electrically by this test structures which is beneficial for early technology development as well as productive in-line monitoring. Highly accelerated WLR tests use the metal self-heating effect for temperature stress acceleration. It is shown here that the design of interconnects with respect to the critical metal line and the periphery of the tested metal line has a large impact on the stress temperature. A carefully designed test structure guarantees the ability to test for different EM failure modes (upstream, downstream). The presented experimental data focuses on the investigation of different process splits.