Deep insights into the mechanism of nitrogen on the endurance enhancement in ferroelectric field effect transistors: Trap behavior during memory window degradation
Yuanquan Huang, Hongye Yuan, Bowen Nie, Tiancheng Gong, Yuan Wang, Shuxian Lv, Pengfei Jiang, Wei Wei, Yang Yang, Junshuai Chai, Zhicheng Wu, Xiaolei Wang, Qing Luo
Abstract
The nitridation process can significantly improve the quality of the interfacial layer and suppress the unrecoverable electron trapping of the interfacial states during cycling, which is the main cause of endurance enhancement. In this work, through in-depth analysis of defect behavior during memory window (MW) degradation in ferroelectric field effect transistors (FeFETs), it is found that the degradation of FeFET devices with SiON interfacial layer starts within the HZO layer, while the degradation process of FeFET devices with SiO2 interlayer initially begins at the interlayer and then penetrates into the HZO layer. First, the MW degradation processes of nitridation/non-nitridation devices are measured and compared. Moreover, through the extended measure-stress-measure method, three types of defects are defined and the defect behaviors including trapping kinetics and energy locations during degradation are systematically investigated. The mechanism of nitrogen on the endurance enhancement is finally revealed. These results are valuable to better understand the reliability issues of FeFET and pave the way for future process optimization.