Radiation hardened 64 K/256 K EEPROM technology

Abstract

This paper summarizes the status of 64 K and 256 K radiation hardened EEPROM devices that are being produced for space and strategic applications at Northrop Grumman Corporation. These devices use Silicon-Oxide-Nitride-Oxide-Semiconductor (SONOS) technology which provides improved total dose radiation hardness over floating gate devices. Circuit design techniques provide good resistance to single event and transient radiation effects. Several CMOS/SONOS devices are being produced including an 8 K/spl times/8 EEPROM, a 32 K/spl times/8 EEPROM (in development), plus mixed mode ASICs. This technology has been demonstrated to have better than 10 year retention at 80/spl deg/C after 10/sup 4/ programming cycles. The EEPROMs utilize a radiation hardened CMOS process technology currently specified at 300 Krad(Si) total dose hardness. Both n-channel and p-channel SONOS memory transistors are currently in use, but the EEPROMs are based on n-channel SONOS.