First Demonstration of Double-Gate IGZO Transistors with Ideal Subthreshold Swing of 60 mV/dec at Room Temperature and 76 mV/dec at 380 K Over 5 Decades and gm Exceeding 1 mS/µm with Contact Length Scaling
Wenjie Zhao, Shenwu Zhu, Qijun Li, Qianlan Hu, Honggang Liu, Anyu Tong, Min Zeng, Ru Huang, Yanqing Wu
Abstract
In this work, contacted length scaling for atomic-layer-deposited IGZO transistors has been systematically investigated. The back-gate IGZO transistors with excellent reliability under high stress electric field of 6 MV/cm, exhibit negligible performance degradation as contact length scales to 40 nm, due to the optimized contact resistance. The 70 nm double-gate IGZO transistor has demonstrated an ideal subthreshold swing of 60 mV /dec at room temperature and 76 mV/dec at elevated temperature of 380 K over 5 decades for the first time, attributed to the high -quality interface and enhanced electro-static control. Furthermore, the shorter 35 nm double-gate transistor with contact length of 80 nm has achieved a record-high transconductance exceeding 1 mS/µm and an on-state current over 1.93 mA/µm, representing the highest performance among all IGZO-based transistors. When the contact length is further reduced to 40 nm, the transconductance remains above 0.75 mS/µm and the on-state current exceeds 1.33 mA/µm for the 35 nm channel length transistor, respectively. This work indicates the tremendous potential of IGZO transistors for high-density three-dimensional integrated circuit applications with excellent scaling properties.