Revealing Asymmetric Off-State Drain/Source Stress Reliability and Mechanisms in IGZO-FETs

Amorphous indium-gallium-zinc oxide field-effect transistors (IGZO-FETs) face significant reliability challenges, primarily due to the amorphous nature of the IGZO channel and the defects within the gate oxide (GOX). In this work, we investigate the reliability of IGZO-FETs under off-state drain/source stress (ODS/OSS) conditions and reveal distinct asymmetric shifts in <i>V</i>_th and SS that challenge the conventional assumption of drain/source symmetry. These effects are attributed to two concurrent mechanisms: electron detrapping at the IGZO/GOX interface driven by drain/source-induced electric fields and the dynamic reconfiguration of the density of states (DoS) within the IGZO channel. By developing a physics-based model, we have accurately captured the measured current-voltage (<i>I</i>-<i>V</i>) dynamics and demonstrated that the interplay between electron detrapping and disorder-induced DoS reorganization within IGZO governs the observed asymmetric degradation. These findings highlight the critical impact of off-state stresses on IGZO-FET reliability and advance the fundamental understanding of amorphous oxide semiconductor behavior in 3D integration technologies.