Using Programmable Delay Monitors for Wear-Out and Early Life Failure Prediction
Chang Liua, Eric Schneiderb and Hans-Joachim Wunderlichc
University of Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart, Germany
achang.liu@iti.uni-stuttgart.de
bschneiec@iti.uni-stuttgart.de
cwu@informatik.uni-stuttgart.de
ABSTRACT
Early life failures in marginal devices are a severe reliability threat in current nano-scaled CMOS devices. While small delay faults are an effective indicator of marginalities, their detection requires special efforts in testing by so-called Fasterthan- At-Speed Test (FAST). In a similar way, delay degradation is an indicator that a device reaches the wear-out phase due to aging. Programmable delay monitors provide the possibility to detect gradual performance changes in a system and allow to observe device degradation. This paper presents a unified approach to test small delay faults related to wear-out and early-life failures by reuse of existing programmable delay monitors within FAST. The approach is complemented by a test-scheduling which optimally selects frequencies and delay configurations to significantly increase the fault coverage of small delays and to reduce the test time.
Keywords: Faster-Than-At-Speed Test, Small Delay Faults, Aging Monitors, Programmable Delay Monitors.
