Reactive sputtering of ferroelectric AlScN films with H₂ gas flow for endurance improvement

Abstract

Abstract The impact of H 2 gas flow in the reactive sputtering process to 60 nm-thick ferroelectric Al 1− x Sc x N films is investigated with x of 0.26 (high-Sc) and 0.12 (low-Sc). Al 1− x Sc x N films exhibit clear ferroelectric switching, confirming the robustness against reducing ambient. The dielectric constants ( ε i ) as well as the leakage current decrease, and the breakdown field ( E BD ) increases with H 2 flow. Although the remanent polarization ( P r ) decreases with H 2 flow, the wake-up effect is suppressed for the high-Sc film, and the fatigue effect is weakened for the low-Sc film. By probing the change in the coercive field ( E c ) after the switching cycle test, we anticipate oxygen impurities bonded to Sc and Al atoms are the source of wake-up and fatigue effects, respectively. As a result, a high endurance cycle of 2 × 10 7 times was achieved for low-Sc films with H 2 flow.