Enhanced Reliability, Switching Speed and Uniformity for Ferroelectric HfZrO_x on Epitaxial Ge Film by Post Deposition Annealing for Oxygen Vacancy Control

Instead of employing post metal annealing (PMA), post deposition annealing (PDA) was proposed to crystalize HfZrO _x (HZO) into the ferroelectric phase on an epitaxial Ge film with higher reliability. Due to the absence of top electrode/HZO reaction during annealing, PDA-processed HZO intrinsically possesses a better capability to control the amount of oxygen vacancies ( ${V}_{o}$ ). It is physically and electrically confirmed that the amount of ${V}_{o}$ for the PDA-HZO is suppressed by 10.3%. Due to fewer ${V}_{o}$ , the PDA-based device shows a higher switching speed than the counterpart by a factor of 12. By integration with an AlON interfacial layer, the PDA-based device reveals superior reliability performance to that by PMA in terms of robust endurance of 10 ⁸ cycles, stable retention up to ten years, and smaller imprint. In addition, the PDA process also leads to enhanced remanent polarization ( ${P}_{r}$ ) uniformity among devices by 61.3% due to reduced grain size. Furthermore, additional thermal annealing after metal deposition hardly affects the devices’ performance, implying that the PDA process can be integrated with a subsequent dopant activation annealing to implement ferroelectric field-effect transistors (FeFETs) and pave a viable way to advance the development of high-reliability Ge-based FeFET memory.