Measurement and modeling of duty-cycle effects due to NBTI

One of the most important requirements for modeling of the long-term effects of negative bias temperature instability (NBTI) on device/circuit response is an understanding of how to include the effect of duty cycle on the threshold voltage shift. Since NBTI is known to be comprised of both permanent and recoverable components, a measurement protocol must be established enabling separation of these components and then their recombination to predict the shift for different duty cycles. In the work reported here, we have endeavored to address these issues by combining pulsed and pseudo-DC stressing/relaxation methods.