Title :
On the origin of the dispersion of erased threshold voltages in flash EEPROM memory cells
Author :
Essemi, D. ; Riccò, Bruno
Author_Institution :
Dipt. di Elettronica, Inf. e Sistemistica, Bologna Univ., Italy
fDate :
5/1/2000 12:00:00 AM
Abstract :
This work investigates the origin of the dispersion of tunnel-erased threshold voltages (VT) in flash EEPROM memory cells. A clear correlation between cell-to-cell variations of tunnel current IT and dispersion of erased VT is demonstrated by looking at the IT characteristics and the erasing characteristics corresponding to channel and source injection as well as at the dependence of IT and VT dispersion on device area and tunnel polarity. Experimental evidence is provided that nonuniform injection at poly-Si/SiO2 interface is a major cause of erased VT dispersion
Keywords :
electric potential; flash memories; integrated memory circuits; tunnelling; Si-SiO2; cell-to-cell variations; device area; erased threshold voltages dispersion; erasing characteristics; flash EEPROM memory cells; nonuniform injection; oxide conductivity variations; polySi/SiO2 interface; tunnel current characteristics; tunnel polarity; tunnel-erased threshold voltages; Character generation; Conductivity; Current measurement; Dispersion; Doping; EPROM; Nonvolatile memory; Pulse measurements; Threshold voltage; Tunneling;
Journal_Title :
Electron Devices, IEEE Transactions on
