A new fast switching NBTI characterization method that determines subthreshold slope degradation during stress

Abstract

For PMOSFET devices NBTI is a serious reliability concern. Because of recovery effects careful stress and measurement methods must be used to determine threshold voltage (VT) degradation. These methods typically assume that mobility and subthreshold slope (SS) degradation are minimal. Recent paper have pointed out that this assumption may not be valid. This paper discusses a new fast switching NBTI measurement technique that alternates between two VGS measurement conditions to determine the SS as a function of stress time. In this new method the SS is determined during stress to correctly compensate the VT degradation for SS degradation. In addition, this papter presents SS and VT NBTI degradation data from a 2 nm low and high nitrogen and a 6 nm DGO PMOS device to demonstrate the value of this new method.