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 recombination of charges and the bonding of hydrogen atoms on interface traps. Furthermore, we show that a heating of the whole device and a forward biasing of the emitter-base-diode activate these annealing mechanisms. This biasing deactivates the interface traps by recombination with a part of the streaming charge and results in a local increase in temperature, caused by the current. Both local and global heating yield an additional thermal generation of charges and an increasing diffusivity of hydrogen atoms. Consequently, an additional deactivation and passivation of interface traps is detected