Predicting hard failures and maximum usable range of sige HBTs

This paper presents an overview of the various failure mechanisms observed when a SiGe HBT is operated outside of traditionally-defined electrothermal safe operating areas (SOAs). The concepts of hard and soft safe operating area (SOA) boundaries are defined in this work. This provides two different viewpoints which determine the degradation and failure of a SiGe HBT as a function of bias conditions. Measurements were performed on state-of-the-art SiGe HBTs to measure the hard SOA boundaries in terms of physical parameters such as geometry, layout configuration, and temperature. The outcomes of this work can serve as the stepping-stone to a “red flag” warning mechanism for the detection of hard SOA boundaries within a circuit design environment.