In Situ O₂ Plasma-Treated HfO₂–ZrO₂ Superlattice HZO FeRAMs Exhibiting Enhanced Remnant Polarization and Improved Endurance Performance

Abstract

In this study, HfO2–ZrO2 superlattice (SL) HfZrO2 (HZO) ferroelectric random access memories (FeRAMs) with various HfO2/ZrO2 nanolamination (NL) thicknesses and a 1.5-nm ZrO2 seed layer were fabricated without and with in situ O2 plasma treatment to experimentally investigate and discuss their ferroelectricity and endurance performance. Compared with the conventional HZO FeRAMs, the HfO2–ZrO2 SL HZO FeRAMs with a HfO2 and ZrO2 NL thickness of 1 nm exhibited a higher two remnant polarization ( $2{P} _{\text {r}}$ ) of $43.32~\mu $ C/cm2, nearly wake-up free behavior, stronger fatigue effect immunity, and lower two coercive field ( $2{E} _{\text {c}}$ ) of 2.55 MV/cm. Furthermore, by using an in situ O2 plasma-treated SL HZO thin film for the FeRAMs to greatly suppress the oxygen vacancy generation during cycling, a further improved fatigue effect immunity and significantly reduced pulsed $2{P} _{\text {r}}$ degradation rate ( $\Delta 2{P} _{\text {r}}$ / $2{P} _{\text {r,pristine}}$ ) down to 36.48% after the endurance test of $10^{{9}}$ cycles can be achieved because the in situ O2 plasma-treated SL HZO FeRAMs possess a significantly enhanced HZO thin-film quality. Therefore, the in situ O2 plasma-treated SL HZO FeRAMs are very suitable candidates for embedded nonvolatile memory (eNVM) applications.