Abstract
During the last couple of years new measurement techniques have provided insight into the physics behind the negative bias temperature instability (NBTI) and indicate that the recoverable component of NBTI is due to some kind of charge trapping. As a consequence, charge trapping processes have been investigated and modeled in detail. We review the evolution of the latest charge trapping model by focussing on the correct temperature- and field dependence as well as on the quality of agreement with experimental stress/relaxation curves.