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A temperature-switching irradiation (TSI) sequence has been developed that is based on a first-principles understanding of interface-trap buildup and annealing. The dynamics of interface-trap buildup and annealing during elevated temperature irradiation are described in detail to provide background, context, and enhanced understanding of the TSI method. The method is shown to be a practical and conservative test for enhanced low-dose-rate sensitivity (ELDRS) in linear bipolar devices and ICs. Examples of TSI sequences are shown for target doses up to 200 krad(Si), a range of great practical interest for space applications. The method can be adapted for higher dose applications via similar approaches. Devices that do not exhibit ELDRS respond similar to TSI and high-dose-rate irradiation. [ABSTRACT FROM AUTHOR]

The effect of bias condition on total ionizing dose (TID) of Silicon–Germanium heterojunction bipolar transistors (SiGe HBTs) is investigated. The SiGe HBTs are set at forward, saturated, cutoff, and all-grounded biases during ^60\Co\gamma irradiation. After each irradiation stops, the forward Gummel characteristic and inverse Gummel characteristic are measured, and a 3-D simulation of TID for SiGe HBT is performed. The mechanism of TID in different bias conditions is obtained by analyzing normalized excess base current. The results show that the TID damages are different at various irradiation biases of the SiGe HBT, and the worst bias between forward and inverse Gummel characteristics exhibits inconsistently. The reason could be attributed to different defects produced and accumulated in oxide layers by irradiation at various bias conditions. To be specific, the oxide trap charges (${{\hbox{N}}_{\rm ot}}$) in emitter/base (E/B) Spacer is important to the forward Gummel characteristic, yet the ${{\hbox{N}}_{\rm ot}}$ in LOCOS determines the inverse Gummel characteristic. However, after long time irradiation, the interface states (${{\hbox{N}}_{\rm it}}$) both in E/B Spacer and LOCOS dominate the damage to the SiGe HBT despite in forward Gummel mode or inverse Gummel mode. [ABSTRACT FROM AUTHOR]