Improvement of Memory Window of Silicon Channel Hf₀.₅Zr₀.₅O₂ FeFET by Inserting Al₂O₃/HfO₂/Al₂O₃ Top Interlayer

In this work, we propose a gate structure to enhance the memory window (MW) of Si-channel Hf0.5Zr0.5O2 FeFETs. We achieve an MW of 10.04 V by inserting an Al2O3/HfO2/Al2O3 (AHA) top dielectric interlayer between the ferroelectric Hf0.5Zr0.5O2 layer and the metal gate, where the gate-stack thickness is 14.8 nm. The physical origin is that the Al2O3/HfO2, HfO2/Al2O3, and Al2O3/Hf0.5Zr0.5O2 interfaces can trap charges from the metal gate, contributing to the MW enhancement. This AHA top dielectric multilayer effectively suppresses charge loss compared with a single Al2O3 top dielectric interlayer. Moreover, the de-trapping of charges injected from the metal gate is the primary factor for the degradation of the MW in this structure. Our work provides a guide for improving the MW of FeFET.