Analysis of transient charging components in NBTI degradation studied for TaN gated HfO2/SiO2 dielectrics

Abstract

Threshold voltage (V,h) shift under the NBT-stress of TaN gated HfO2/SiO2 stacked gate dielectrics has been studied by conventional DC and the pulsed measurements. A large Vth shift in the early stage of stress occurs typically within 1 s by the fast transient charging under the stress as well as during the Vth measurement. Contributions of both charging components strongly depend on the film quality and also on the stress conditions. Therefore, an accurate deconvolution of measured DeltaVth into each component is indispensable for accurate lifetime prediction and the understandings of the NBTI reliability.