Research Into Reliability Mechanism And Model Of 2T-EFLASH Device

P-channel floating gate flash memory device with two-transistor structure is widely used in various types of embedded systems by virtue of its high reliability,fast programming and erasure speed and low power consumption.However,the tunnel oxide layer of 2T-EFLASH device is getting thinner as the feature size of the device continues to decrease,which has a serious impact on the reliability of flash memory.In order to improve the reliability of 2T-EFLASH device and evaluate its lifetime,the reliability degradation mechanism and model of 2T-EFLASH device should be investigated in depth.In this work,the endurance degradation mechanism and lifetime model of 2T-EFLASH device is researched in depth.With the help of charge pumping measurements and sentaurus simulations,the damages in the drain overlap region along the tunnel oxide interface and damages in the channel region are verified respectively.Furthermore,the lifetime model of endurance characteristics is established,which shows logarithmic linear relationship between the degradation of the programming threshold ?tp and the number of cycle n.The relative error is 10.3%which satisfies the endurance assessment requirements.The endurance degradation tendency and the lifetime can be extrapolated according to the model.In addition,the degradation mechanism and lifetime model of data retention characteristics of 2T-EFLASH device is studied in detail.The degradation mechanism is revealed and the data retention lifetime model is extracted through the high temperature baking test combined with Arrhenius model.It is demonstrated that the logarithmic of the data retention time is proportional to the reciprocal of the baking temperature and the relative error is 11.1%.The data retention lifetime can be deduced through this model which has a guiding significance to the assessment of data retention characteristics.