Detecting Emerging Wearout Faults

Abstract

Abstract — Aggressive CMOS scaling accelerates transistor and interconnect wearout, resulting in shorter and less predictable lifetimes for microprocessors. Studies show that wearout faults have a gradual onset, manifesting initially as timing faults before eventually leading to hard breakdown. Prior work suggests detecting wearout faults as they begin to affect normal operation, but these techniques require complex circuit and/or microarchitectural changes. Our proposal, FIRST (Fingerprints In Reliability and Self Test), uses existing design-for-test hardware (scanout chains) and infrequent periodic tests under reduced frequency guardbands to observe marginal behavior that is an indication of wearout. FIRST is a low-overhead, complexityeffective methodology for detecting emerging wearout faults before they affect normal operation. We discuss the operation of FIRST error detection, present a model for wearout fault simulation, and demonstrate FIRST’s effectiveness on a portion of a commercial microprocessor design. I.