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

This study presents an experimental demonstration of 3-D-stackable hafnia-based selector-free cross-point FeRAM, with enhanced disturbance immunity achieved through design technology co-optimization (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 <tex-math notation="LaTeX">0.5</tex-math> Zr <tex-math notation="LaTeX">0.5</tex-math> O <tex-math notation="LaTeX">₂</tex-math> (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 ( <tex-math notation="LaTeX">Pᵣ</tex-math> ) of approximately 23 <tex-math notation="LaTeX">μ</tex-math> C/cm <tex-math notation="LaTeX">²</tex-math> , low operation voltage (2.4 V), high endurance (10 <tex-math notation="LaTeX">¹³</tex-math> 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 low-power memory applications.