Kilobyte-Scale, Selector-Free, Temperature-Hard AlScN Ferroelectric Diode Crossbar Arrays

TL;DR

This paper demonstrates the fabrication and characterization of large-scale, high-density, selector-free ferroelectric diode arrays using AlScN, showing high yield, uniform switching, and high-temperature operation suitable for advanced memory applications.

Contribution

It introduces a scalable, CMOS-compatible process for AlScN ferroelectric diode arrays with high density, yield, and temperature resilience, enabling new memory system architectures.

Findings

Achieved 2-kilobyte arrays with 95.2% yield.

Demonstrated stable operation up to 600°C.

Realized selector-free read and write operations.

Abstract

We report the fabrication and characterization of kilobyte-scale, selector-free, ferroelectric (FE) diode crossbar memory arrays based on aluminum scandium nitride (AlScN). Utilizing a fully CMOS back-end-of-line (BEOL) compatible process, we fabricated 2-kilobyte (128 $\times$ 128) arrays with device diameters down to 5 $\mu$m, achieving memory densities up to 2500 bits/mm$^2$. Large-scale electrical characterization across 1000 randomly selected devices reveals a yield rate of 95.2%, a tight switching voltage distribution with a coefficient of variation (CV) of 0.003, and consistent on/off ratios of around 10 with a CV of 0.27. We demonstrate selector-free read and program operations of the array, enabled by the high nonlinearity, rectification, and uniform switching behavior of the FE diodes. Furthermore, we verified consistent ferroelectric switching during array operation at temperatures up to 600 $^\circ$C. Our results highlight the potential of AlScN FE diode arrays for energy-efficient, high-density memory applications and lay the groundwork for future integration in compute-near-memory, high-temperature memory, and analog compute-in-memory systems.