A new self-convergent programming method form multilevel AND-type flash mem
ory is described to accurately control the dispersion of the programmed thr
eshold voltage which is caused by the deviation of the applied voltage or t
he FN tunneling current. Both channel initiated secondary electron injectio
n (CHISEL) and avalanche hot electron injection (AHEI) Following the edge F
N electron ejection can be used as the self-convergent programming techniqu
es. However, CHISEL is shown to be better than AHEI for self-convergent ope
ration due to faster speed, lower voltage, lower power consumption, and bet
ter oxide reliability.