Asymmetric Contact Resistances in IGZO Vertical Channel-All-Around FETs

作者：Xianglie Sun, Wei Yu, Fuwang Yang, Meichen Jin, Chang Liu, Chuanke Chen, Weiwei Li, Di Geng, Shujuan Mao, Zhengyong Zhu, J. Zhang, Guilei Wang, Bok-Moon Kang, Chao Zhao · 发表于：IEEE Electron Device Letters · 年份：2025 · DOI：10.1109/led.2025.3604792 · 被引用次数：5 · 研究领域：Advancements in Semiconductor Devices and Circuit Design、Semiconductor materials and interfaces、Force Microscopy Techniques and Applications

This work investigates the contact resistance asymmetry in Indium-Gallium-Zinc-Oxide vertical channel-all-around field-effect transistors (IGZO VCAA FETs). By a combination of extrapolating the variation in gate voltage (ΔVG) between two types of source/drain (S/D) configurations versus drain current (ID) and nonlinear fitting of the total resistance (RT) versus gate overdrive voltage (VOV), the contact resistances of top contact (RCT) and bottom contact (RCB) are quantitatively characterized. TheRCTandRCBshow values of 11.4 kΩ-μm and 2.1 kΩ-μm, suggesting an inferior contact property formed at the top electrode. Such difference betweenRCTandRCBis derived from the uneven Schottky barrier heights (SBHs) of top and bottom contacts, 220 meV for the former and 100 meV for the latter, respectively. The higher SBH of top contact renders IGZO VCAA FETs behaving like source-gated transistors (SGTs) in the configuration where the top electrode serves as source and the bottom electrode as drain, showing a lower on-state current, an earlier saturation, and a better immunity to drain-induced barrier lowering (DIBL) effect. The approach for characterizing asymmetric contact resistances affords insights and guidelines to optimize performance symmetry in IGZO VCAA FETs.