Dose and Dose Rate Dependence of 8080a Microprocessor Failures

The occurrence of transient upset and catastrophic failure in 8080A microprocessors was investigated over a dose-rate range of 6 × 10-4 to 3 × 10+10 rads/sec. The transient upset and catastrophic failure levels depended on both dose and dose-rate. For example, the dose at which catastrophic failure occurs is 10 times greater at the highest dose-rates investigated than at the lowest. Irradiation was performed using both low energy (45 kV x-ray tube, 200 kV flash x-ray source) and high energy (Co 60, Linac) sources. The observed transient upset and catastrophic failure levels were significantly higher for low energy irradiation than for high energy irradiation. These results have important implications for models of ionizing radiation effects in MOS devices.