A highly CMOS compatible hafnia-based ferroelectric diode

Ming Liu,Qing Luo,Xiaoyan Li,Yan Cheng,Haoran Yu,Peng Yuan,Lu Tai,Yang Yang,Tiancheng Gong,Qiwei Ren,Xiaoxin Xu,Wei Wei,Dashan Shang,Haili Ma,Bing Yu,Jianguo Yang,Rongrong Cao,Rong Huang,Jie Yu,Qi Liu,Yifan Zheng ,Hangbing Lv

doi:10.1038/s41467-020-15159-2

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 Hf0.5Zr0.5O2 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 Hf0.5Zr0.5O2 film and the displacement of oxygen atom, thus unambiguously identified the non-centrosymmetric Pca21 orthorhombic phase in Hf0.5Zr0.5O2 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 109 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.

Highlights

Memory devices with high speed and high density are highly desired to address the ‘memory wall’ issue
The ferroelectric tunneling junction (FTJ) device takes the advantage of a ferroelectric as the barrier material, and has a giant tunnel electroresistance (TER) effect by switching the ferroelectric polarization, which was generally formulated by quantum mechanical electron-tunneling mechanism
The detailed material deposition and device fabrication processes were described in the “Experimental” section and Supplementary Fig. 1

Summary

Introduction

Among various types of nonvolatile memories, ferroelectric random-access memories (FeRAM), which achieve nonvolatility by switching and sensing the polarization state of a ferroelectric capacitor, have been thought of as an excellent memory solution due to its outstanding features of low power, high speed, high endurance, and good retention. The FTJ device takes the advantage of a ferroelectric as the barrier material, and has a giant tunnel electroresistance (TER) effect by switching the ferroelectric polarization, which was generally formulated by quantum mechanical electron-tunneling mechanism In principle, both the on and off states of FTJ obey linear or quasi-linear I–V relationship, which makes it need extra selector device to diminish the sneaking current in the crossbar array.

Methods

Results

Conclusion