Radiation-Hardened Complementary MOS Using SiO2 Gate Insulators

This paper reports the results of a study in which commercially-proven metal-oxide-semiconductor (MOS) processes are modified to provide radiation-hardened complementary MOS (CMOS) circuits. Typical silicon-dioxide (SiO2) gateinsulator processes are used, in conjunction with chromium doping, to fabricate hardened MOS capacitors, n and p channel transistors, and CMOS inverter circuits. The resulting CMOS circuits exhibit excellent electrical and performance characteristics and stability, while accumulating more than 107 rads(Si) ionizing-radiation dose, under worst-case conditions. Observable radiation effects are essentially independent of static bias and are minimum under normal, dynamic operating conditions. The approach is not only compatible with commercial SiO2 processes but appears adaptable to dielectric-isolation, such as silicon-on-sapphire (SOS). Hence, the demonstrated technology represents a "breakthrough" in the development of cost-effective, stable CMOS devices for use in advanced military systems.