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

Abstract

Hf0.5Zr0.5O2 (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 Al2O3 were integrated into HZO film as different MLs. Among them, the device with ZrO2 ML achieves the excellent double remnant polarization (2Pr) of 41.7 μC cm−2 under 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–1 and 3 MV cm–1, respectively. Additionally, the FE capacitor with ZrO2 ML demonstrated an enhanced reliability characterizations, including a stable 2Pr of 40.7 μC cm–2 after 4.3 × 109 cycles. 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.