1.6 Conclusion

Electrical measurements, in particular MSM and OTF, have allowed to characterize NBTI on a phenomenological basis, but only give little insight into the underlying physical processes. Nevertheless, it has been possible to formulate criteria which can be used to the evaluate the candidates for NBTI models (see Section 1.4). Additionally, TDDS experiments have revealed that NBTI is attributed to a superposition of individual charge capture or emission events with certain field and temperature dependences. In contrast to MSM and OTF, the TDDS findings shed light on the microscopic processes behind NBTI and therefore give an additional criteria for any NBTI model.

Despite of all this experimental information, none of the NBTI models proposed so far could fully explain all the findings from the aforementioned measurements. This is especially true for the RD model along with all its variants based on a dispersive nature of the interface reaction and/or the hydrogen reaction. As a consequence, the focus of this thesis is put on some kind of charge trapping as a possible explanation for NBTI.