A Modeling Framework for NBTI Degradation Under Dynamic Voltage and Frequency Scaling

A modeling framework is proposed to predict the degradation and recovery of threshold voltage shift (Delta V-T) due to negative bias temperature instability. Double interface reaction-diffusion model with transient trap occupancy model is used to predict the generation and recovery of interface traps (Delta V-IT). Empirical stretched exponential equations are used to capture hole trapping and detrapping in preexisting traps (Delta V-HT). The framework consists of uncoupled contributions from Delta V-IT and Delta V-HT and is capable of accurately predicting the ultrafast measured Delta V-T during dc, arbitrary multicycle dc, ac, and mixed-mode dc-ac stress. It can predict pulse duty cycle and frequency dependence of ac degradation and also dynamic voltage and frequency scaling waveforms encountered in actual circuits.