A Thermionic Electron Emission Model for Charge Retention in SAMOS Structure

Abstract

Charge retention in SAMOS structures at elevated temperatures is effectively described by a thermionic electron emission model from a floating polysilicon gate into the surrounding oxide. Experimental results showed sufficiently good agreement with the theoretical model. The barrier height and collision frequency derived from the experiments are reasonable (1.24 eV and 2.5×104/sec, respectively). Long term data retention in floating gate EPROM's can also be predicted by this model.

A new extrapolation law for data-retention time-to-failure of nonvolatile memories

“…Model would require, but, as reported in the literature [2], [3], [4], [5], an activation energy increasing with temperature would be necessary. A good global fitting is instead obtained with a new Model, where (2) with a characteristic temperature of data-retention (in Fig.…”

“…A good global fitting is instead obtained with a new Model, where (2) with a characteristic temperature of data-retention (in Fig. 2 K).…”

“…Temperature accelerated life-tests on NVM's are widely used as characterization methods for charge retention capability [2]. According to this methodology, for a given charge-loss threshold criterion, failure rates obtained at hightemperature (200 C-300 C) are extrapolated to nominal operating conditions.…”

Self-consistent simulation on multiple activation energy of retention characteristics in charge trapping flash memory

“…The trend shows that the device with the oxide of 4 nm has a unique slope while thinner devices have a slope varying according to temperature. It is known that the Arrhenius plot shows unique activation energy when thermal emission is the dominant charge loss mechanism [4]. As the tunneling current becomes important for the cases of thinner oxide, the slope of the Arrhenius plots decreases in low temperature region.…”

“…For actual production of flash cells, it is important to understand and properly model the data retention characteristics to guarantee the desired lifetime of the device. The widely used method predicting the data lifetime is an extrapolation using the activation energy, which is represented by the slope of the Arrhenius plot, as used in the conventional Floating Gate (FG) cell [4]. Usually, this method is used under the assumption that the activation energy is constant (satisfying Arrhenius equation) within the temperature of interest.…”