Write/erase degradation in source side injection flash EEPROM's: characterization techniques and wearout mechanisms

In this paper, an in-depth analysis is presented of the write/erase degradation in Source Side Injection Flash EEPROM cells, using the HIMOS cell as a typical example. The different mechanisms governing the degradation are studied and quantified by combining UV erasure and I-V measurements with a charge pumping analysis. Both procedures are shown to disclose two effects contributing to the change of the threshold voltage window: a change in the amount of charge on the floating gate due to a decrease in the injection current, accompanied by the series effect of oxide and interface charges locally trapped above the channel. By correlating the results from charge pumping and I-V measurements, an estimate is made of the spatial extent of the damaged region.>