Finding defects with fault models

A process is presented to validate fault models used in fault diagnosis. Known defects are inserted, using a focused ion beam (FIB), into production ICs and their behavior is compared to that predicted in fault simulation. The fault model is refined until it matches the observed defect behavior. The process is then repeated with known defects in unknown (“blind”) locations, and necessary modifications to the model are again made. Finally, the model is used to diagnose chips with unknown defects. Experimental results on several chips demonstrate the value of the approach, which can be extended to test pattern generation and test quality estimation as well as fault diagnosis