Hafnia-Based High-Disturbance-Immune and Selector-Free Cross-Point FeRAM

Abstract

This study presents an experimental demonstration of 3-D-stackable hafnia-based selectorfree cross-point FeRAM, with enhanced disturbance immunity achieved through design technology cooptimization (DTCO). Considering ferroelectric (FE) dynamics, the disturbance behavior of FE devices has been systematically and quantitatively examined using the proposed "pulse-disturb" analysis method. Through the optimization of grain uniformity and interfacial layers, the fabricated Hf 0.5 Zr 0.5 O 2 (HZO) FE capacitor exhibits large grain size exceeding 30 nm with record best disturbance immunity among FE-HZO. It also achieves a significant improvement of MW in selector-free FeRAM operation and enhanced remnant polarization (P r ) of approximately 23 µC/cm 2 , low operation voltage (2.4 V), high endurance (10 13 cycles), long retention capability (ten years), and excellent potential for 3-D stacking. Moreover, to address the multiple pulses disturb issue, a novel "disturb-recovery" pulsing method is proposed, showing multidisturb-free operation for practical cross-point array applications. Based on the above strategies, 1-kbit selector-free cross-point FeRAM array is experimentally demonstrated with successful read/write operation, indicating its great potential for high-density and lowpower memory applications.