7.7 Conclusion

In the previous chapter it has been demonstrated that the TSM captures the essential features of NBTI degradation curves but fails to explain the time constant plots obtained by TDDS experiments. This indicates that this model does not correctly reflect the nature of the microscopical trapping process behind NBTI. Therefore, the charge transfer reaction has been refined by using a more accurate description of the NMP process based on the adiabatic potentials of a defect. Furthermore, an additional metastable state has been introduced. With these extensions of the eNMP, it has also been able to reproduce the experimental findings of TDDS. In particular, the eNMP allows to reproduce the time constant plots and explain the ‘normal’ as well as the ‘anomalous’ defect behavior depending on the shape of the adiabatic potentials in the configuration coordinate diagram. Besides that, it gives an explanation for the occurrence of tRTN and aRTN, both seen in experiments.