Erratic erase in flash memories - part I: basic experimental and statistical characterization

This paper presents experimental results and statistics about the erratic erase in Flash Memories, setting the basis for any physical modeling of the phenomena and data comparison. Statistical parameters like the reliability function and the failure rate have been measured and modeled by analytical functions showing that all cells of an array may potentially exhibit erratic events. By mapping the physical position of each erratic bit in a sector and using an equivalent cell approach, it has been possible to establish a correlation between the erratic phenomena and the intrinsic amorphous nature of SiO/sub 2/. Tail bits of the erased distribution have been shown to be caused by erratic events suggesting a unique physical cause for the two phenomena. The relation between positive and negative shifts has also been discussed and overerase risks caused by erratic behaviors have been estimated.