Development of a novel ultrafast direct threshold voltage (UF-DV_T) technique to study NBTI stress and recovery

An ultrafast measurement technique is developed to directly determine threshold voltage shift (ΔVT) during Negative Bias Temperature Instability (NBTI) stress and recovery from the microsecond (μs) timescale. The technique is developed around a measurement setup that integrates Ultrafast On-the-fly (UF-OTF) linear drain current (IDLIN) and Ultrafast Measure-stress-measure (UF-MSM) setup hardware by a custom microcontroller-based trigger generator. The technique offers an in-built scheme for converting measured IDLIN degradation (ΔIDLIN) to conventional (peak gm based) ΔVT and alleviates the need for any postprocessing correction. The developed measurement setup is used to obtain and compare time evolution, as well as the oxide field (EOX) and temperature (T) dependence of ΔVT during NBTI stress, as calculated using different existing methods. Based on the comparison, a simpler and faster single-point drop-down modification of the UF-MSM part of the technique is proposed