250 GHz heterojunction bipolar transistor: From DC to AC reliability

Continued node shrinks have given rise to the emergence of ultrafast SiGe BiCMOS opportunities. This class of technology integrates high performance HBTs with state of art CMOS technology and targets. millimeter wave applications such as 77 GHz automotive radars and non invasive imaging for airport security. In order to reach this performance, HBTs are designed to operate at high current density and often in some cases at voltages beyond the collector - emitter (C/E) breakdown voltage with an open circuit base (BV_CEO). Regarding these severe conditions which are susceptible to create serious damage and limit the device performance, reliability emerges as an important challenge. In this work, LF noise, DC current measurements and DCIV method are used to evaluate the interface trap density induced in Si/SiO₂ interfaces during forward stress and systematically extract reliability model parameters. We propose a global time to failure (TTF) model for the reliability qualification of high speed SiGe HBTs. Finally, the application of the degradation model to RF circuit is proposed and discussed.