Experiments and Modeling of Defect Dynamics and BTI Behavior in Doped InO TFTs During 400 °C Postprocessing Forming Gas Annealing

We investigate the impact of a monolithic 3-D (M3D) integration process-critical$400~^{\circ } $C postprocessing forming gas annealing (FGA) on the electrical performance, reliability, and defect evolution of oxide-channel thin-film transistors (TFTs), combining systematic experiments with density-functional-theory (DFT)-based liquid-quench molecular-dynamics (MD) simulations. Indium tungsten oxide (IWO) TFTs are employed as a model system and encapsulated with a thin 3-nm Al2O3/3 nm HfO2hybrid layer that effectively suppresses external hydrogen ingress. We reveal a nonmonotonic evolution of device behavior during FGA, governed by initial densification followed by partial crystallization. Short-duration FGA (10 min) induces channel densification and the formation of shallow, delocalized defect states, leading to pronounced positive bias temperature instability (PBTI) degradation and the emergence of a characteristic transfer-curve “kink.” With prolonged annealing (>40 min), partial crystallization of the oxide channel occurs, stabilizing hydrogen in deep, localized defect states, suppressing hydrogen mobility, and restoring device reliability. As a result, the PBTI shift is reduced to 10.4 mV after 2000 s of stress, accompanied by complete elimination of the transfer-curve kink. These findings provide a mechanistic understanding of hydrogen–defect interactions during high-temperature postprocessing FGA and demonstrate that appropriate hydrogen-blocking encapsulation enables oxide-channel TFT integration without compromising electrical performance or reliability.