Résumé
In this work, the effect of electrical stress and high X-ray Total Ionizing Dose (TID) exposures is studied for BiCMOS 55 nm SiGe:C HBTs technology. HBTs were exposed to a maximum X-ray TID of 520 krad(SiO2) and in terms of electrical stress to a high current injection (i.e. VBE = 1.1 V in the direct gummel-plot configuration). For both stress techniques, the effect of the cumulative X-ray dose and electrical stress duration on the degradation of the base current, IB, is investigated. A linear degradation is observed after X-ray exposure. The relative base current ∆IB/IB between pre-stress and post-stress is approximately 8. For electrical stress, degradation is generally more pronounced, but increasing or decreasing erratically with the duration of the stress. To investigate a possible detrapping mechanism, a two-step annealing process was conducted at temperatures of 100 °C and 130 °C. Annealing results showed a significant difference between the two degradation processes. A recovery of 90% is measured after X-ray irradiation stress even after two cycles of high-dose X-ray irradiation, while no recovery is observed after electrical stress. TCAD simulations of X-ray irradiation effects were used to investigate and compare the experimental data regarding the impact of created trap densities and emitter-width on the degradation of DC characteristics. This enabled us to highlight the role of the EB junction, with a marked perimeter effect.