A 256K high performance CMOS EEPROM technology

A high performance CMOS technology has been developed for a 256K EEPROM. Using this technology, a 54um²EEPROM cell has been realized. The high coupling ratio of the cell, together with the use of an ultrathin oxynitride layer as a tunneling dielectric, allows cell programming voltages as low as 17 volts at a programming time of 0.1 msec. The intrinsic cell endurance has been improved to greater than 10⁸cycles. The utilization of an optimized interpoly dielectric process and low temperature reflow glass prevent the degradation of tunneling dielectric. A special gettering technique reduces tunneling dielectric defects as well as junction leakage, thus paving the way to 5 volt-only operation over full military temperature range.