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.