High performance and nearly wake-up free Hf_0.5Zr_0.5O₂ ferroelectric capacitor realized by middle layer strategy with BEOL compatibility

Hf_0.5Zr_0.5O₂(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 under the low operating electric field. ZrO₂, HfO₂, and Al₂O₃were integrated into HZO film as different MLs. Among them, the device with ZrO₂ML achieves the excellent double remnant polarization (2<i>P</i>_r) of 41.7<i>μ</i>C cm^-2under the operating electric field of 2 MV cm^-1. Moreover, ultralow wake-up ratios of around 0.08 and 0.05 were observed under 2 MV cm^-1and 3 MV cm^-1, respectively. Additionally, the FE capacitor with ZrO₂ML demonstrated an enhanced reliability characterizations, including a stable 2<i>P</i>_rof 40.7<i>μ</i>C cm^-2after 4.3 × 10⁹cycles. This work provides the perspective to optimize both the ferroelectricity and reliability, while maintains the ultralow wake-up ratio in HfO₂-based FE through ML engineering.