A unified model for AC bias temperature instability

Abstract

Usually AC Bias Temperature Instability is modeled as consisting of a recoverable and a permanent component, assuming these components originate from different physical mechanisms. In this work we introduce a model based on charge trapping and detrapping that can properly account for both components. Under switching bias (AC stress), fast traps are able to follow the bias point change, while slow traps act according to an equivalent time constant, not being able to follow the bias point change. We present an extension to our previous model to properly account for these effects, and we provide a simple compact model to help circuit designers to cope with both components of BTI due to charge trapping. Model is validated by comparison to experimental data and Monte Carlo simulations.