Oxygen-Atom Incorporated Ferroelectric AlScN Capacitors for Multi-Level Operation

The effect of oxygen-atom incorporation in 50-nm-thick ferroelectric Al0.89Sc0.11N films was investigated. The fabricated films exhibited a high remanent polarization ( ${P}_{\text {r}})$ exceeding $100~\mu $ C/cm2, irrespective of the oxygen content studied. An increase in oxygen content led to a decrease in coercive field ( ${E}_{\text {c}})$ from 5.2 to 4.4 MV/cm and an increase in the static dielectric constant ( $\varepsilon _{\text {i}})$ from 15 to 19. This was likely due to the formation of substitute O and Al vacancy complex defects to ease N-atom displacement. Additionally, higher oxygen content resulted in imprint effect elimination, leakage current reduction, and breakdown field ( ${E}_{\text {BD}})$ enhancement, which are beneficial for ferroelectric memory applications. The gentle and linear relationship between ${P}_{\text {r}}$ and the electric field ( ${E})$ enabled precise control of partial polarization switching, supporting multi-level operation. Although issues related to fatigue and endurance cycles remain to be addressed, the high ${P}_{\text {r}}$ and potential for multi-level operation are suitable for crossbar-based analog in-memory computing.