Geometric Design of Confined Conducting Filaments in Resistive Random Access Memory by Al2O3 Nanodome-Shaped Arrays (NDSAs) via Glancing-Angle Deposition Technology Toward Neuromorphic Computing

Resistive random access memory (RRAM) is vital to neuromorphic computing applications. However, filamentary RRAM cells are affected by transitions from abrupt switching to analog switching. In this study, we develop Al2O3 nanodome-shaped arrays (NDSAs) by glancing-angle deposition technology (GLAD) to geometrically confine the conducting filaments (CFs), for which conducting atomic force microscopy (C-AFM) was performed to analyze positions and dimensions of filaments. For the Pt/HfO2/75% Al2O3 NDSAs/TiN device, the dimension of the CFs can be restricted to 10-12 nm, whereas for the Pt/HfO2/TiN device, the CFs were formed with a dimension of similar to 50 nm. The device first yielded multiple weak CFs that subsequently transformed to stronger and larger CFs when the coverage of Al2O3 NDSAs was reduced to 55% while Pt/HfO2/75% Al2O3NDSAs/TiN device exhibited synaptic features with more linear potentiation and depression, demonstrating the analog switching. The controllable coverages of Al2O3 NDSAs render the geometric design more promising as a memristor for future applications in neuromorphic computing.

Automated summary

This study investigates the use of Al2O3 nanodome-shaped arrays (NDSAs) to geometrically confine conducting filaments (CFs) in resistive random access memory (RRAM) cells for neuromorphic computing applications. It demonstrates that the controllable coverages of Al2O3 NDSAs show promising potential for future memristor applications in neuromorphic computing.