The effects of proton irradiation on the operating voltage constraints of SiGe HBTs

The effect of proton irradiation on operating voltage constraints in SiGe HBTs is investigated for the first time in 120 GHz and 200 GHz SiGe HBTs. A variety of operating bias conditions was examined during irradiation, including terminals grounded, terminals floating, and forward active (FA) bias operation. The excess base current degradation at 5.0/spl times/10/sup 13/ p/cm/sup 2/ was similar in all cases. BV/sub CEO/ and BV/sub CBO/ showed no significant signs of degradation with irradiation. We also investigated for the first time the impact of radiation on SiGe HBTs biased under so-called "unstable" conditions (i.e., operating point instabilities). In the case of unstable bias conditions, device degradation under proton exposure is significantly different than for stable bias, and bias conditions can play a significant role in the damage process, potentially raising issues from a hardness assurance perspective.