Comprehensive Study of Endurance Fatigue in the Scaled Si FeFET by in-situ Vth Measurement and Endurance Enhancement Strategy

Abstract

The endurance degradation mechanism in Si FeFET has attracted great research interest. However, the reports mainly focused on large-scale devices, owing to the external current measurement limitations of modern equipment. In this work, we study the endurance degradation mechanism in the scaled n-FeFET by in-situ Vth measurement to overcome the size limitation. We find that excess electron injection rather than hole injection plays a key role in the charge trapping behavior. As the endurance cycles increase, the Vth after the program pulse positively shifts due to less electron de-trapping. The Vth after erase pulse negatively shifts due to more hole trapping when the Vg changes from -1V to -4V and no hole de-trapping occurs when the Vg changes from -4V to 0 V. The donor trap generation and hole trapping are the dominant factors of endurance failure in the scaled nFeFET.