Proton and gamma radiation effects in a new first-generation SiGe HBT technology

The effects of proton and gamma irradiation on a new commercially available SiGe technology are investigated for the first time. The results of proton irradiation on a differential SiGe HBT LC oscillator are also reported in order to gauge circuit-level impact. These findings indicate that the dc, ac, and RF circuit performance is total dose tolerant up to Mrad-level equivalent total dose. A technology comparison is drawn between the results of this work and the three other previously reported SiGe technologies. We find that all reported SiGe HBT technologies to date show acceptable proton radiation tolerance up to Mrad levels. Transistor mismatch is also investigated here for the first time in SiGe HBTs. Collector current mismatch data as a function of emitter geometry are reported both before and after exposure for this SiGe HBT technology. We find only minimal changes in device-to-device mismatch after radiation exposure, suggesting that these SiGe HBTs should be suitable for use in analog circuits, which are critically dependent on the matching characteristics of the requisite devices.