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

Abstract

In recent literature several measurement methods were introduced to characterize the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> -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 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> based on the assumption that the subthreshold slope is not affected by NBTI. In this paper we disprove the universality of this assumption. V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> 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 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> . We clearly demonstrate this effect with our measurements. We introduce a new smart V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> extraction methodology offering both shortest possible delay times with customary equipment and consideration of NBTI-impact on subthreshold slope.