TRANSIENT RADIATION VULNERABILITY OF MONOLITHIC BINARY CIRCUITS

An investigation was made to experimentally determine the pulsed ionizing radiation vulnerability of critical computer binary circuits, and study basic radiation-induced failure mechanisms. The test specimens were three bipolar transistor circuits fabricated by the monolithic integrated circuit technique, and one metal-oxide-semiconductor (MOS) integrated circuit. Experimental studies consisted of determining electrical circuit performance, and induced transient responses when exposed in a pulse ionizing radiation environment. Failure mechanisms were related analytically, where possible, to the characteristics of the circuit, and to electrical parameter degradation. Two failure modes were observed in the binary circuits. Transient response at circuit logic outputs was of sufficient magnitude to temporarily obscure the logic state of the circuit. Additionally, the intense radiation environment was sufficient to cause a radiation-induced change-of-state, with a permanent loss of stored information in the circuit. Electrical parameter degradation of the bipolar transistor circuits was insignificant after exposure to approximately 10,000 rads (Si). However, significant variations in circuit performance were observed for the MOS circuits when exposed to the same ionizing radiation intensities. (Author)