Combined Effects of Radio Frequency and Electron Radiation on CMOS Inverters

摘要

This research examines the measurement methodology, and the results of, the combined effects of electron and radio frequency irradiation (500kHz) on a CMOS Hex Inverter, CD4069UB. There have been many studies in recent years on the effects of electron radiation and electromagnetic interference on integrated circuits, however the combined effects have not been measured. A major obstacle for in-situ electron irradiation experiments is the over current hazard that exists to measurement equipment that comes from taking real-time, in-situ measurements. To overcome this, a test circuit was designed and built to allow for real-time in-situ measurement of the output voltage, current and the inverter power. This test circuit provides real-time measurement of the inverter's threshold voltage with respect to electron dose. During this research pre- and post-electron irradiation measurements (1MeV electrons with fluences up to 8x1015 (e-/cm-2) at various fluxes), combined with RF were made using a continuous 500kHz RF signal coupled into the inverter input. The data provided insight into the total dose effect as opposed to a dose rate effect on the inverter. A significant negative threshold voltage shift was observed along with a limited amount of annealing. Inverters that were outliners from nominal VTC characteristics displayed an enhanced failure rate. The combined effects of radio frequency are inconclusive, but indicate that the RF decreases post irradiation annealing.