Hot electron and hot hole degradation of UHV/CVD SiGeHBT's

We investigate the degradation in current gain and low-frequency noise of S iGe HBT's under reverse emitter-base stress due to hot electrons (forward-c ollector stress) and hot holes (open-collector stress), Contrary to previou s assumptions we show that hot electrons and hot holes with the same kineti c energy generate different amounts of traps and hence have a different imp act on device degradation. These results suggest that the accuracy of using forward-collector stress as an acceleration tool and reliability predictor must be carefully examined. We also present, for the first time, the effec t of Ge profile shape on the reliability of SiGe HBT's, as well as discuss measurements on SiGe HBT's as a function of device geometry and temperature .