A physics-based 3-D potential and threshold voltage model for undoped triple-gate FinFET with interface trapped charges

A threshold voltage model based on the solution of the three-dimensional (3-D) Poisson’s equation for an undoped triple-gate (TG) fin-shaped field-effect transistor (FinFET) with localized interface trapped charge is presented in this paper. Such localized interface charge created by either hot carrier injection or bias temperature instability degrades the threshold voltage and thereby the overall performance of FinFET devices. The proposed model considers the location of the interface traps and the length of the damaged region. The potential distribution and the threshold voltage of the TG FinFET obtained from the model are compared with data from technology computer-aided design simulations, which validates the model for different device dimensions, interface trapped charge densities, damaged region lengths, and drain biases. The results show that the variation of the threshold voltage mainly depends on the length of the damaged region and the thickness of the oxide but is independent of the fin width and height. Furthermore, short-channel effects such as threshold voltage roll-off and drain-induced barrier lowering are investigated, considering both positive and negative interface traps.