This paper presents a novel approach to estimate the rising and failing behavior of Nth-order ON-state current by dynamic negative-bias temperature instability (DNBTI), with a comparison between experimental data and a modified DNBTI model in PMOS body-tied FinFETs for the first time. The modified model was proposed to predict not only Nth-order DNBTI behavior but also temperature and stress bias effects. The fin-width dependence was analyzed, and different trends between silicon-on-insulator and body-tied FinFETs were explained with the extracted DNBTI model parameters: stress time, oxide-field strength, and temperature. The proposed model closely matched the measured static lifetime.