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 (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{\text {r}})$ </tex-math></inline-formula> exceeding <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100~\mu $ </tex-math></inline-formula>C/cm2, irrespective of the oxygen content studied. An increase in oxygen content led to a decrease in coercive field (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text {c}})$ </tex-math></inline-formula> from 5.2 to 4.4 MV/cm and an increase in the static dielectric constant (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon _{\text {i}})$ </tex-math></inline-formula> 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 (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text {BD}})$ </tex-math></inline-formula> enhancement, which are beneficial for ferroelectric memory applications. The gentle and linear relationship between <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{\text {r}}$ </tex-math></inline-formula> and the electric field (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E})$ </tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{\text {r}}$ </tex-math></inline-formula> and potential for multi-level operation are suitable for crossbar-based analog in-memory computing.