Radiation hardened 64-bit CMOS/SOS RAM

Radiation hardening procedures have been implemented in design, analysis and fabrication of a 64-bit CMOS/SOS RAM. The resultant circuit is a moderately complex (714 transistor), dielectrically isolated integrated circuit which features high performance and high radiation tolerance. Typical electrical parameters include 120 nsec read-access time and 1 microwatt/bit standby power dissipation. The SOS construction minimizes radiation-induced transient photocurrents while a hardened gate insulator provides immunity to total dose effects. Transient radiation upset levels exceed 30 Grad (Si)/sec for short pulses and ionizing dose hardness exceeds 1 krad (Si). A neutron fluence of 365 trillion neutrons per sq cm had no effect on circuit operation beyond that expected from the ionizing radiation alone.