Issue 42, 2024

Conductive filament distribution in nano-scale electrochemical metallization cells

Abstract

We report a combined experimental and theoretical study of the spatial distributions and sizes of conductive filaments in nano-scale electrochemical metallization (ECM) cells. Each cell comprises a silver nanocube as active electrode, a titanium dioxide (TiO2) or aluminum oxide (Al2O3) layer as dielectric, and a highly-doped silicon substrate as passive counter electrode. Following electroforming of the ECM cell and subsequent mechanical delamination of the silver nanocubes, current maps at previous particle locations reveal an intriguing metal distribution in the TiO2, with preferential accumulation close to the original locations of the nanocube edges. We assign this behavior to electric field enhancements close to the cube edge positions. In contrast, filaments in Al2O3 layers show a comparatively homogenous distribution, which may be assigned to its lower dielectric permittivity. By increasing the oxide thickness, the total area of conductive spots in the current maps increases monotonically for both materials. Kinetic Monte-Carlo simulations of ion migration dynamics in TiO2 confirm the experimental observations, describing both the preferred locations and oxide thickness-dependent metal loadings associated with filament formation. Overall, our findings are highly valuable for the design of future electrochemical metallization cells, especially in the sub-100 nm regime, where optimal filament control is of major importance for achieving lowest device-to-device variability.

Graphical abstract: Conductive filament distribution in nano-scale electrochemical metallization cells

Supplementary files

Article information

Article type
Communication
Submitted
10 Jul 2024
Accepted
07 Oct 2024
First published
14 Oct 2024
This article is Open Access
Creative Commons BY license

Nanoscale, 2024,16, 19675-19682

Conductive filament distribution in nano-scale electrochemical metallization cells

M. Speckbacher, M. Rinderle, O. Bienek, I. D. Sharp, A. Gagliardi and M. Tornow, Nanoscale, 2024, 16, 19675 DOI: 10.1039/D4NR02870H

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