双层多晶FLOTOX E2PROM的阈值电压退化特性

基于FLOTOX E^2PROM结构，分析了影响FLOTOX E^2PROM可靠性的主要因素，包括可编程窗口退化、电荷保持特性退化及与时间有关的隧道氧化层击穿(TDDB)等，发现FLOTOX的可靠性与隧穿氧化层的质量密切相关．实验表明，擦／写电压应力周期、脉；中电压应力大小及脉冲宽度的变化都会影响FLOTOX E^2PROM阈值电压的变化，分析认为隧穿氧化层中产生的缺陷(陷阱电荷)是引起FLOTOX E^2PROM阈值电压退化的主要原因，隧道氧化层中的陷阱电荷通过影响注入电场使阈值电压增加或减少．

Threshold Voltage Degradation Features of Double Polysilicon FLOTOX E2PROM

Based on the structure of FLOTOX E2PROM cell, th e main factors influencing the reliability of FLOTOX E2PROM were analyzed, incl uding 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, t he pulse voltage amplitude and the pulse width all affect the variation of the t hreshold voltage. It is also found that the trap charge resulting from the tunne l oxide proves to be the main cause of the threshold voltage degradation of FLOT OX E2PROM, as it can increase or decrease the threshold voltage by affecting t he injected electric field.