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

Abstract

An ultrafast measurement technique is developed to directly determine threshold voltage shift (ΔV_T) 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 (I_DLIN) 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 I_DLIN degradation (ΔI_DLIN) to conventional (peak g_m based) ΔV_T 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 (E_OX) and temperature (T) dependence of ΔV_T 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.