Patent ID: 6233175
Filing Date: 2001-05-15
Classification: G11C

Abstract:
A method of programming a flash EEPROM device to have multi-level programmed states, the method comprising:(a) selecting a cell in the flash EEPROM device to be programmed;(b) selecting a threshold voltage to which the cell will be programmed, wherein the selected threshold voltage is selected from the group including V.sub.t1, V.sub.t2, and V.sub.tn,(c) applying a voltage V.sub.g to a gate of the cell to be programmed;(d) applying a voltage V.sub.d to a drain of the cell to be programmed;(e) applying a voltage V.sub.s to a source of the cell to be programmed, wherein the voltage V.sub.s is selected from the group V.sub.s1, V.sub.s2, and V.sub.sn, wherein V.sub.s1, V.sub.2, and V.sub.sn result in threshold voltages V.sub.t1, Vt.sub.2, and V.sub.tn, respectively; and(f) adjusting a lateral electric field, E.sub.l =V.sub.d -V.sub.s, of the cell being programmed to keep the lateral electric field E.sub.l equal to V.sub.d.