New Self-Convergent Programming Method for Multilevel AND Flash Memory

A new self-convergent programming method for multilevel AND-type flash memory is described to accurately control the dispersion of the programmed threshold voltage which is caused by the deviation of the applied voltage or the FN tunneling current. Both channel initiated secondary electron injection (CHISEL) and avalanche hot electron injection (AHEI) following the edge FN electron ejection can be used as the self-convergent programming techniques. However, CHISEL is shown to be better than AHEI for self-convergent operation due to faster speed, lower voltage, lower power consumption, and better oxide reliability.