ANNEALING OF DEGRADED NPN-TRANSISTORS - MECHANISMS AND MODELING

We report on the annealing of degraded npn-transistors, which includes a new model describing the decrease of base current during annealing. We found that two mechanisms are responsible for annealing: the recom bination of charges and the bonding of hydrogen atoms on interface tra ps. Furthermore, we show that a heating of the whole device and a forw ard biasing of the emitter-base-diode activate these annealing mechani sms. This biasing deactivates the interface traps by recombination wit h a part of the streaming charge and results in a local increase in te mperature, caused by the current. Both local and global heating yield an additional thermal generation of charges and an increasing diffusiv ity of hydrogen atoms. Consequently, an additional deactivation and pa ssivation of interface traps is detected.