Characteristics degradation of the SiGe HBT under electromagnetic field stress

This paper describes a new reliability study in SiGe Heterojunction Bipolar Transistors (HBTs) by which the electromagnetic field aggression effects can be identified. Base current deviation mechanism with current gain degradation is studied for the first time. Reverse Gummel plots and capacitance characterizations indicate that the electromagnetic field stress induces traps not only at the emitter–base spacer’s oxide, but also at the collector–base spacer’s oxide. These traps induce generation/recombination centers, and leads to excess non-ideal base currents. Two-dimensional physical simulations have been used to analyse the impact of this degradation mechanism on the device behavior. As a consequence of introducing surface recombination centers at emitter–base and collector–base spacer’s oxide, a non-ideal base current rises up in agreement with the experimental data extracted. As the density of interface traps increases, the charge contributed by these interface states causes a broadening in the base current response and the capacitances deviation.