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This paper uses a physics-based TCAD degradation model to examine the accumulated stress damage of SiGe HBTs under pseudodynamic mixed-mode stress as a function of both electrical stress bias and temperature. The temperature dependence of mixed-mode stress damage is fully explored, beginning with impact-ionization calibration, and then by identifying and calibrating the dependence of scattering length and hydrogen diffusion parameters of the degradation model. After calibrating the model across electrical bias and temperature, the effectiveness and limitations of accumulated stress damage while varying electrical bias and while varying temperature are identified, and the implications of this aging model for circuit designers are discussed.Index Terms-Accumulated mixed-mode stress degradation, hot-carrier damage, lucky electron model, reliability, safe operating area (SOA), SiGe HBT, temperature dependence.

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Large-signal ( P 1 dB ) and small-signal (OIP3) radio frequency (RF) linearities of silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) fabricated in a new fourth-generation 90-nm SiGe BiCMOS technology operating at cryogenic temperatures are investigated. The SiGe BiCMOS process technology has an f T / f max of 300/350 GHz. SiGe HBTs with two different layout configurations, collector-baseemitter (CBE) and CBE-base-collector (CBEBC), were characterized over temperature. Both dc and ac figures-of-merit are presented to aid in understanding the linearity, and to provide an overall performance comparison between the two layout configurations. The extracted peak f T / f max for CBE and CBEBC at 78 K are 387/350 and 420/410 GHz, respectively. The P 1 dB and OIP3 linearity metrics for both configurations are comparable. Source-and load-pull measurements were performed at each temperature at 8 and 18 GHz, with the devices biased at a J C of 18 mA/μm 2 . Two-tone measurements over bias were also performed at 300 and 78 K with 50-terminations for the source and load impedances. The 50 results follow a similar response to the source-and load-pull measurements at 300 and 78 K, and demonstrate that the small-signal linearity of the SiGe HBTs is not adversely impacted by operation at cryogenic temperatures. The CBEBC configuration demonstrated the most consistent RF linearity performance at cryogenic temperature out of the two layout options.