A critical examination of the mechanics of dynamic NBTI for PMOSFETs

The physics of frequency-dependent shift in transistor parameters due to negative bias temperature instability (NBTI) is examined using numerical and analytical solutions of the reaction-diffusion model (R-D). We find that the magnitude of NBTI degradation depends on frequency through a complex interplay of reaction- and diffusion-limited trap generation processes, and that the intrinsic symmetry of the stress and relaxation phases can account for the relatively weak frequency dependence of the NBTI phenomenon. We also show that the model is consistent with the broad features of the dynamic NBTI problem and can provide an adequate framework to discuss NBTI issues.