A highly CMOS compatible hafnia-based ferroelectric diode

TLDR

High‑speed, high‑density memory devices are needed to overcome the memory‑wall bottleneck. Using atomic‑resolution STEM, the authors linked Hf₀.₅Zr₀.₅O₂ polarization to oxygen displacement, confirmed the non‑centrosymmetric Pca₂₁ phase, and fabricated an 8‑layer 3D ferroelectric diode. The diode achieves 20 ns switching, >10⁹‑cycle endurance, and >100 nonlinearity, enabling self‑selective operation and promising future memory hierarchy.

Abstract

Abstract Memory devices with high speed and high density are highly desired to address the ‘memory wall’ issue. Here we demonstrated a highly scalable, three-dimensional stackable ferroelectric diode, with its rectifying polarity modulated by the polarization reversal of Hf 0.5 Zr 0.5 O 2 films. By visualizing the hafnium/zirconium lattice order and oxygen lattice order with atomic-resolution spherical aberration-corrected STEM, we revealed the correlation between the spontaneous polarization of Hf 0.5 Zr 0.5 O 2 film and the displacement of oxygen atom, thus unambiguously identified the non-centrosymmetric Pca2 1 orthorhombic phase in Hf 0.5 Zr 0.5 O 2 film. We further implemented this ferroelectric diode in an 8 layers 3D array. Operation speed as high as 20 ns and robust endurance of more than 10 9 were demonstrated. The built-in nonlinearity of more than 100 guarantees its self-selective property that eliminates the need for external selectors to suppress the leakage current in large array. This work opens up new opportunities for future memory hierarchy evolution.