Enhanced Device Characteristics of Hybrid‐Channel (Poly‐Si/IGO) Structures with Ga₂O₃ and Al₂O₃ Interlayers by Suppressing Oxidation‐Induced Variability for Ultra‐High‐Density 3D NAND Flash Memory Applications

Hybrid‐channel (HC) structures integrating polycrystalline silicon (poly‐Si) and oxide semiconductors offer a promising path toward high‐mobility, thermally stable architectures for next‐generation 3D NAND flash memory. However, high‐temperature annealing required for oxide crystallization often induces interfacial oxidation, leading to device variability and degraded performance. To address this challenge, this study proposes a novel HC structure incorporating an ultrathin interlayer of Ga 2 O 3 or Al 2 O 3 between the poly‐Si and In‐Ga‐O (IGO) channels. This interfacial layer effectively suppresses poly‐Si loss and the formation of non‐uniform interfacial oxide, reducing poly‐Si degradation from 5 to 1.7 nm and interfacial oxide growth from 7.4 to 2.5 nm. As a result, threshold voltage variation improves significantly, from ±0.45 to ±0.24 V and ±0.40 V for Ga 2 O 3 and Al 2 O 3 , respectively, while average cell current density increases from 1.87 to over 2.0 µA µm −1 . Memory windows expand accordingly, and both interlayers enable a field‐effect mobility exceeding 100 cm 2 V·s −1 . These findings demonstrate the importance of interfacial engineering in HC devices and establish a viable route for integrating thermally stable oxide semiconductors into ultra‐high‐density 3D memory applications.