Negative Capacitance Oxide Thin-Film Transistor With Sub-60 mV/Decade Subthreshold Swing

• Published in: IEEE electron device letters 2019-05, Vol.40 (5), p.826-829
• Main Authors: Li, Yuxing, Tian, He, Yang, Yi, Ren, Tian-Ling, Liang, Renrong, Wang, Jiabin, Jiang, Chunsheng, Xiong, Benkuan, Liu, Houfang, Wang, Zhibo, Wang, Xuefeng, Pang, Yu
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Buried structures; Capacitance; Electric potential; ferroelectric hafnium oxide; Ferroelectric materials; Ferroelectricity; Hysteresis; Logic gates; negative capacitance; Oxide thin film transistor; Power consumption; Semiconductor device measurement; Semiconductor devices; subthreshold swing; Thin film transistors; Transistors; Voltage measurement; Zinc oxide
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2019.2907988

In this letter, we demonstrate an integrated negative capacitance oxide thin-film transistor (NC-OTFT) based on ferroelectric Hf 0.5 Zr 0.5 O 2 (HfZrO) film. The buried-gated TiN/HfZrO/Al 2 O 3 structure is developed with indium zinc oxide as its channel. The transfer characteristics are measured with 1.2-V supply voltage. The NC-OTFT 15-nm HfZrO/6-nm Al 2 O 3 shows 2.5 × 10 7 ON/OFF current ratio and 120-mV anticlockwise hysteresis. The subthreshold swing (SS) values of this NC-OTFT are lower than those of the control devices without HfZrO. The reverse SS shows sub-60 mV/decade about 2 orders of drain current. The minimal reverse and forward SS values are 52.8 and 74.1 mV/decade, respectively. The NC-OTFT with 8-nm HfZrO/6-nm Al 2 O 3 is inspected with considerably narrower hysteresis of 50 mV. Its reverse and forward SS values reach as low as 63.6 and 69.8 mV/decade, respectively. The NC effect is observed in the gate-stack capacitance of the NCOTFTs. This NC-OTFT is promising for low operating voltage and low power consumption applications.