High performance and nearly wake-up free Hf0.5Zr0.5O2 ferroelectric capacitor realized by middle layer strategy with BEOL compatibility

Abstract Hf 0.5 Zr 0.5 O 2 (HZO) has drawn great attention owing to its excellent ferroelectricity, sub-10 nm scalability, and CMOS compatibility. With regard to increasingly restrict thermal budget and power consumption, conventional HZO films need further optimization to meet these demands. Here, we propose a middle layer (ML) strategy aiming to enhance ferroelectricity and inhibit wake-up effect of ferroelectric (FE) capacitors compatible with back-end of line (BEOL) under the low operating electric field. ZrO 2 , HfO 2 , and Al 2 O 3 were integrated into HZO film as different MLs. Among them, the device with ZrO 2 ML achieves the excellent double remnant polarization (2Pr) of 41.7 μC/cm 2 under the operating electric field of 2 MV/cm. Moreover, ultralow wake-up ratios of around 0.08 and 0.05 were observed under 2 MV/cm and 3 MV/cm, respectively. Additionally, the FE capacitor with ZrO 2 ML demonstrated an enhanced reliability characterizations, including a stable 2Pr of 40.7 μC/cm 2 after 4.3×10 9 cycles. This work provides the perspective to optimize both the ferroelectricity and reliability, while maintains the ultralow wake-up ratio in HfO 2 -based ferroelectric through middle layer engineering.