ZrO2 Ferroelectric Field-Effect Transistors Enabled by the Switchable Oxygen Vacancy Dipoles
Huan Liu, Yue Peng, Genquan Han, Yan Liu, Ni Zhong, Chun‐Gang Duan, Yue Hao
Abstract
Abstract This paper investigates the impacts of post-rapid thermal anneal (RTA) and thickness of ZrO 2 on the polarization P and electrical characteristics of TaN/ZrO 2 /Ge capacitors and FeFETs, respectively. After the RTA ranging from 350 to 500 °C, TaN/ZrO 2 /Ge capacitors with 2.5 and 4 nm-thick amorphous ZrO 2 film exhibit the stable P . It is proposed that the ferroelectric behavior originates from the migration of the voltage-driven dipoles formed by the oxygen vacancies and negative charges. FeFETs with 2.5 nm, 4 nm, and 9 nm ZrO 2 demonstrate the decent memory window (MW) with 100 ns program/erase pulses. A 4-nm-thick ZrO 2 FeFET has significantly improved fatigue and retention characteristics compared to devices with 2.5 nm and 9 nm ZrO 2 . The retention performance of the ZrO 2 FeFET can be improved with the increase of the RTA temperature. An MW of ~ 0.46 V is extrapolated to be maintained over 10 years for the device with 4 nm ZrO 2 .