Statistical Investigation of Al$_{2}$O$_{3}$ Insertion Layer on the Endurance of Hf$_{0.5}$Zr$_{0.5}$O$_{2}$ Films: Abrupt Endurance Degradation and Mechanism

Abstract

In this work, the effect of ultrathin Al$_{\bm {2}}$O$_{\bm {3}}$ insertion layer on the endurance characteristics of Hf$_{\bm {0.5}}$Zr$_{\bm {0.5}}$O$_{\bm {2}}$ (HZO) layer is statistically investigated. It was found that the ultrathin Al$_{\bm {2}}$O$_{\bm {3}}$ insertion layer will not improve or reduce the endurance of HZO devices within the low operation voltage range. However, an abrupt endurance degradation phenomenon is observed when increasing the operation voltage to a specific value and the endurance of HZO/Al$_{\bm {2}}$O$_{\bm {3}}$ layer is sharply lower than HZO device. This phenomenon is finally explained by the leakage-current-assist polarization switching mechanism after quantitatively extracting the continuous charge density during the polarization switching by pulse measurement. The findings of this work provide a deep understanding of the endurance failure mechanism of Ferroelectric/Dielectric (FE/DE) devices and are helpful for the reliability investigation of the gate stack in Fe-FET.