D. Esseni et B. Ricco, On the origin of the dispersion of erased threshold voltages in flash EEPROM memory cells, IEEE DEVICE, 47(5), 2000, pp. 1120-1123
This work investigates the origin of the dispersion of tunnel-erased thresh
old voltages (V-T) in flash EEPROM memory cells. A clear correlation betwee
n cell-to-cell variations of tunnel current I-T. and dispersion of erased V
-T is demonstrated by looking at the I-T characteristics and the erasing ch
aracteristics corresponding to channel and source injection as well as at t
he dependence of I-T and V-T dispersion on device area and tunnel polarity.
Experimental evidence is provided that nonuniform injection at polySi/SiO2
interface is a major cause of erased V-T dispersion.