An 8K EEPROM using the SIMOS storage cell

An 8192 bit MOS floating-gate EEPROM has been developed and transferred to volume production. The memory uses a two-transistor SIMOS cell for nonvolatile storage of alterable data. The cell is programmed by channel injection of hot electrons while electrical erasure is achieved by tunneling of cold electrons through a thin oxide. Standard production parts show a minimum endurance of 10/SUP 3/ program-erase cycles. The extrapolated data retention is at least 10 years of operation in a 70/spl deg/C ambient, while the number of read cycles is unlimited. Cell design features provide reliable programming combined with minimum sensitivity to fabrication tolerances. Special circuit design, however, ensures programmability of deeply erased cells and avoids electrical stress to the cell unintentionally affecting the programmed information. A novel read amplifier design allowed the realization of an access time of less than 350 ns.