A 4-MB NAND EEPROM WITH TIGHT PROGRAMMED VT DISTRIBUTION

This paper describes a 5-V-only 4-Mb (512K x 8 b) NAND EEPROM with tight programmed threshold voltage (V(t)) distribution, controlled by a novel program verify technique. A tight programmed V(t) distribution width of 0.8 V for the 4-Mb cell array is achieved. By introducing a compact row-decoder circuit, the die size of 7.28 mm x 15.31 mm is accomplished using 1.0-mu-m design rules. A unique twin p-well structure has made it possible to realize low-power 5-V-only erase/program operation easily and 100K cycle endurance.