Review on Ferroelectricity and Atomic Characterization of Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub> in FeRAM
Bowen Shen, Benjamin Yang, Mingcheng Shi, Wen Sun, Huanan Liu, Yi Ding, Bin Gao, Qian He, Yuyan Wang, Jianshi Tang, Huaqiang Wu
Abstract
Hafnia-based ferroelectric memory has drawn extensive attention for its outstanding advantages─such as BEOL compatibility and ability to aggressively scale down. Recent research has extensively investigated the material sciences behind device performance, and optimizations have been achieved in different aspects: including optimizing stack growth and phase composition, reducing the coercive electric field and imprint effect, improving polarization and endurance number, etc. The overall correlation between materials physics and device properties in hafnia-based ferroelectric memory has not been well examined. This article provides a detailed overview of various parameters related to hafnia-based ferroelectric memory, which is divided into the following parts: I. device operation and related circuits; II. aspects related to ferroelectricity, such as polarization, coercive electric field, retention, wake-up and fatigue, speed, and imprint; III. annealing temperature and phase transition; IV. interface processing, including metal electrodes and interlayers; V. atomic characterization, e.g., XRD, PFM and TEM. At the conclusion of this review, we also reviewed the current research hotspots of major memory companies and research institutions, discussed the challenges faced by ferroelectric memory devices, and proposed promising research directions for the future. We hope this article will guide researchers and inspire further studies on hafnia-based memory devices.