Fast electromigration wafer mapping for wafer fab process monitoring and improvement

In this work, a set up for fast wafer level electromigration (WL-EM) is developed with the use of a standard electrical analyser, a semi-auto probe station with a hot chuck, and a PC. EM tests on multiple test structures are carried out simultaneously and tests are done at multiple locations (EM mapping) across the wafer. Measured data are imported into MS EXCEL and analysed with a macro automatically. Good correlations are demonstrated between the fast WL-EM test and classical package level EM at 0.1% failure rate. For several years reliable EM monitoring charts are created with the fast WL-EM set up. The fast EM mapping test does not only exploit the advantages of fast WL-EM test in terms of short throughput time and low cost (without packaging) for process monitoring, the additional information on EM performance across the wafer makes the test extremely valuable for process improvement.