Variation-Aware Defect Characterization at Cell Level

Abstract

Small Delay Faults (SDFs) are an indicator of reliability threats even if they do not affect the behavior of a system at nominal speed. Various defects may evolve over time into a complete system failure, and defects have to be distinguished from delays due to process variations which also change the circuit timing but are benign. Based on Monte-Carlo electrical simulation at cell level, in this work it is shown that a few measurements at different operating points of voltage and frequency are sufficient to identify a defect cell even if its behavior is completely within the specification range. The developed classifier is based on statistical learning and can be annotated to each element of a cell library to support manufacturing test, diagnosis and optimizing the burn-in process or yield.