Case study of flash memory failure analysis for page erase fail

Failure Analysis (FA) consists of fault verification, isolation, defect tracing, characterization and physical analysis. Flash memory is widely used in data storage. High density cell array makes flash memory prone to defects. In this paper, a NOR flash page failure case was studied. The failed page, consisting of 8 word lines and 512 bytes, cannot be erased. Light emission could help isolate the defect location from horizontal level, but could not tell which layer the defect was at or what kind of defect it was. So rigorous failure analysis need to be used to narrow the fault location step by step, and eventually found the failure root cause.