Effect of Grain Orientation on NBTI Variation and Recovery in Emerging Metal-Gate Devices

This letter identifies and investigates the effect of grain orientation (GO) on negative-bias temperature instability (NBTI) characteristics of emerging metal-gate devices. A modified reaction-diffusion model is presented for estimating the effect of GO on NBTI. It is shown that neglecting the GO effect leads to substantial underestimation of the impact of the gate-oxide electric field (
E
_OX
) on the threshold voltage degradation (Δ
V
_TH
). Moreover, GO results in significant fluctuation in
E
_OX
and, hence, fluctuation in NBTI for ultrascaled CMOS devices. In addition, in FinFETs, stand-alone GO-induced gate-oxide electric field not only results in Δ
V
_TH
fluctuation but also decelerates the recovery process.