Response of advanced bipolar processes to ionizing radiation

Ionizing radiation induced gain degradation in microcircuit bipolar polysilicon and crystalline emitter transistors is investigated. In this work, ⁶⁰Co irradiation testing was performed on bipolar test structures. The effects of collector bias, dose rate, and anneal temperature are discussed. Major differences in the radiation response of polysilicon emitter transistors are demonstrated as a function of dose rate. The worst-case gain degradation occurs at the lowest dose rate complicating hardness assurance testing procedures. The dose rate and anneal data suggest that MIL-STD-883B Test Method 1019.4 is non-conservative for polysilicon emitter transistors, which show enhanced radiation hardness over the crystalline emitter transistors