Abstract: Based on the structure of FLOTOX E2PROM cell‚the main factors influencing the reliability of FLOTOX E2PROM were analyzed‚including the degradation of the programmable windows‚the degradation of the charge retention characteristics and the time-dependent dielectric breakdown （TDDB）．It is found that the reliability of FLOTOX is much correlative with the quality of the tunnel oxide．A series of experiments show that the write／erase period‚the pulse voltage amplitude and the pulse width all affect the variation of the threshold voltage．It is also found that the trap charge resulting from the tunnel oxide proves to be the main cause of the threshold voltage degradation of FLOTOX E2PROM‚as it can increase or decrease the threshold voltage by affecting the injected electric field．

Key words: FLOTOX E2PROM, threshold voltage, trap charge, reliability