Reliability Characterization Issues for Nanoscale Flash Memories: A Case Study on 45-nm NOR Devices

This paper shows that the reliability characterization of nanoscale Flash memories requires an accurate control of the adopted experimental tests, preventing spurious issues to emerge and alter the basic conclusions on the investigated reliability constraints. To this aim, the paper reports a case study on a 45-nm NOR technology, where the experimental investigation of the activation energy for damage recovery during post-cycling bakes and of distributed-cycling effects is substantially affected by parasitic threshold-voltage (VT) drifts, activated by the repeated acquisition of the whole array VT map during the experiment. Only when this spurious effect is taken into account, the typical 1.1-eV activation energy for damage recovery and the effectiveness of the conventional distributed-cycling schemes are correctly demonstrated on the investigated technology.