Reliability review of 250 GHz fully self aligned heterojunction bipolar transistors for millimeterwave applications

Reliability performances of fully self aligned heterojunction bipolar transistors were investigated under high current and voltage stress conditions. We point out in this paper that generation-recombination traps induced by reverse bias stress can be repaired by forward bias. This is possible thanks to high enough device temperature (strong self-heating condition). Low frequency noise measurements and HICUM modelling of power dissipation refine this analysis. Finally, degradation of base-collector junction was investigated under mixed-mode stress and reveals a predominance of defects induced in the space charge area by impact ionization.