Investigating the impact of gate stacks on ALD IGZO transistors via source/drain contact characterization
Abstract
Achieving co-optimization of performance and bias stability is crucial for enabling broader applications of indium-gallium-zinc oxide (IGZO) transistors in next-generation electronics. In this work, back-gate IGZO transistors with different gate stacks are systematically characterized to elucidate the role of interfacial layers (ILs) between the IGZO channel and the HfO2 insulator in device performance and bias stability. The transistor with the HfO2/ZrO2 stack exhibits a near-zero threshold voltage of −0.02 V and a low subthreshold swing of 75.2 mV/dec, outperforming counterparts with HfO2 or Al2O3 ILs. Driven by the larger chemical potential gradient at the IGZO/HfO2 interface, the IGZO film deposited on the HfO2 stack contains the highest concentration of oxygen vacancies (OVs). A large fraction of induced OVs structurally relax into deep-level traps that pin the Fermi level (EF) and impede electron injection at source/drain (S/D) contacts. In contrast, the IGZO films on ZrO2 and Al2O3 ILs exhibit substantially lower OV concentration and thus weaker EF pinning, resulting in reduced S/D contact barriers. Bias stress stability measurements further highlight the critical importance of both robust gate stacks and stable IGZO/high-k interfaces. Ultimately, this gate stack engineering offers a feasible pathway to fabricate high-performance and reliable IGZO transistors for advanced applications.
Article Details
Journal Info
Applied Physics Letters
American Institute of Physics
Authors (13)
Zhan-Yuan Huang
School of Microelectronics, College of Integrated Circuits and Micro-Nano Electronics, Fudan University 1 , Shanghai 200433, ; , Shanghai 201203, ; , Jiaxing, Zhejiang Province 314100,
Zhi-Huai Liu
School of Microelectronics, College of Integrated Circuits and Micro-Nano Electronics, Fudan University 1 , Shanghai 200433, ; , Shanghai 201203, ; , Jiaxing, Zhejiang Province 314100,
Zi-Ying Huang
School of Microelectronics, College of Integrated Circuits and Micro-Nano Electronics, Fudan University 1 , Shanghai 200433, ; , Shanghai 201203, ; , Jiaxing, Zhejiang Province 314100,
Kuan Liang
Department of Applied Physics, Research Institute for Smart Energy, The Hong Kong Polytechnic University 2 , Hong Kong 999077,
Chao Xu
Cai-Yu Shi
School of Microelectronics, College of Integrated Circuits and Micro-Nano Electronics, Fudan University 1 , Shanghai 200433, ; , Shanghai 201203, ; , Jiaxing, Zhejiang Province 314100,
Lei Shen
Key Laboratory of Functional Polymer Materials of Ministry of Education; Tianjin Key Laboratory of Functional Polymer Materials; Institute of Polymer Chemistry, College of Chemistry
Luo-Qiang Wang
Key Laboratory of Advanced Display and System Application, Ministry of Education, Shanghai University 3 , Shanghai 200072,
Ye Zhu
Xing-Wei Ding
Key Laboratory of Advanced Display and System Application, Ministry of Education, Shanghai University 3 , Shanghai 200072,
Wei-Min Li
Jiangsu Leadmicro Nano-Technology Company Ltd 4 ., Wuxi 214000,
David Wei Zhang
Hong-Liang Lu
School of Microelectronics, College of Integrated Circuits and Micro-Nano Electronics, Fudan University 1 , Shanghai 200433, ; , Shanghai 201203, ; , Jiaxing, Zhejiang Province 314100,