ABSTRACT
An important reliability concern in SiGe HBTs is related to long-term degradation effects induced by hot carriers (HCs). While in MOSFETs HC mechanisms produce a degradation of drain current and transconductance, as well as a threshold voltage shift, in bipolar transistors the HC damage is mainly related to the creation of Si dangling bonds acting as trap states at the semiconductor–insulator interfaces. The improved frequency performances of state-of-the-art SiGe HBTs have been achieved at the cost of significantly increased operating current densities and lower breakdown voltages. The stress tests were conducted on devices biased in a common-emitter configuration under bias conditions close to the SOA border. Since these conditions are accelerating like in conventional MM tests, a long stress time was required to observe an impact on the electrical characteristics.
