This paper presents quasi-3-D simulation results of SEE-induced charge coll
ection in UHV/CVD SiGe HBTs. Depending on the bias and load condition, a si
gnificant fraction of electrons can be collected by the emitter rather than
the collector. Most of the generated holes are collected by the substrate
for deep ion strikes, and by the base for shallow ion strikes. A higher sub
strate doping can worsen the upset of the circuit function, despite the red
uced total amount of charge collected. A lower substrate doping and a lower
collector-substrate junction reverse bias are desired to improve SEU hardn
ess.