This paper presents quasi-3-D simulation results of SEE-induced charge collection in UHV/CVD SiGe HBTs. Depending on the bias and load condition, a significant 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 substrate doping can worsen the upset of the circuit function, despite the reduced total amount of charge collected. A lower substrate doping and a lower collector-substrate junction reverse bias are desired to improve SEU hardness.

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In an experiment aboard the Hughes Corporation Leasat vehicle at geosynchronous orbit, single event upsets (SEU) have been continuously monitored in a memory consisting of 93L422 RAMs. Using simultaneous measurements of the high energy galactic cosmic ray and solar flare particle environment from The University of Chicago experiment aboard the IMP-8 satellite, together with a Leasat mass distribution model and ground test measurements of the SEU susceptibility for the 93L422, accurate estimates of the SEU rate are calculated based on several improvements to the standard methods.These results are discussed and compared to the Leasat flight observations.

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