The impact of mechanical stress on the total-dose response of linear bipolar transistors with various passivation layers

In this work, we investigate how externally applied mechanical stress impacts the total dose hardness and enhanced low-dose-rate sensitivity of linear bipolar ICs fabricated with different passivation layers. To determine the effects of externally applied stress and/or radiation exposure on the current gain, various compressive or tensile stresses were applied to lateral PNP bipolar transistors at the wafer level, using a cantilever method. The devices were then exposed to 10-keV X-rays or Cs-137 γ-rays. The effect of externally applied stress on pre and post irradiation gain degradation is found to be relatively minor compared to the effects of changes in passivation layers on the radiation response of devices.