Die-level adaptive test: Real-time test reordering and elimination

This paper introduces an adaptive test method to dynamically control test flow and test contents with continuous per die updates of test fail rates. The method employs Bayesian statistics to model a separate fail rate for each test. Test reordering and elimination is based on statistics of these predicted fail rates and is naturally monitored by a wafer based reset. Wafer sort test response data for two 65nm integrated circuit products is used to demonstrate this method. Test time reductions of about 30% are achieved with quality levels within industry expectations.