Investigation of Endurance Degradation Mechanism of Si FeFET With HfZrO Ferroelectric by an In Situ V<sub>th</sub> Measurement
Xianzhou Shao, Junshuai Chai, Fengbin Tian, Shujing Zhao, Jiahui Duan, Xiaoyu Ke, Xiaoqing Sun, Jinjuan Xiang, Kai Han, Yanrong Wang, Hao Xu, Xiaolei Wang, Jing Zhang, Wenwu Wang, Tianchun Ye
Abstract
We propose an in situ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> measurement method to investigate the endurance fatigue mechanism of Si ferroelectric field-effect transistor (FeFET) with HfZrO ferroelectric. The in situ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> measurement method means that a pulsed current-voltage measurement is embedded during the quasi-static capacitance-voltage (QSCV) measurement. Based on this method, the trapped charges can be extracted as a function of the gate voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{g}{)}$ </tex-math></inline-formula> . We find that: First, the trapped electrons and holes show asymmetric de-trapping dynamics. Excess electrons continuously de-trap within the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{g}$ </tex-math></inline-formula> ranging from the maximum positive value to ferroelectric reverse switching. However, the trapped holes do not de-trap when the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{g}$ </tex-math></inline-formula> changes from the minimum negative value to 0 V. Second, the increase of donor trap density is the key to endurance fatigue. During endurance fatigue, the total amounts of trapped electrons are unchanged near the maximum positive voltage, but the amounts of de-trapped electrons decrease when the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{g}$ </tex-math></inline-formula> returns to 0 V due to donor trap density increases. In addition, we apply our method in the scaled FeFET to overcome the measurement limitation of gate charges ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}_{m}{)}$ </tex-math></inline-formula> by the nowadays equipment.