A novel multi-point NBTI characterization methodology using Smart Intermediate Stress (SIS)

Abstract

In recent literature several measurement methods were introduced to characterize the Vth-degradation due to NBTI considering the recovery phenomenon. To our knowledge each method has a severe problem or at least a significant disadvantage. Either there are long delay times, the accuracy is not satisfactory or it is not possible to implement the method with customary equipment. A compromise is to perform a one point measurement in the subthreshold region and calculate Vth based on the assumption that the subthreshold slope is not affected by NBTI. In this paper we disprove the universality of this assumption. Vth determination using a one point measurement can lead to imprecise values. This extraction method disregards changes of the subthreshold slope due to NBTI, however a change of the slope impacts the extracted Vth. We clearly demonstrate this effect with our measurements. We introduce a new smart Vth extraction methodology offering both shortest possible delay times with customary equipment and consideration of NBTI-impact on subthreshold slope.