A non-pyrophoric precursor for the low temperature deposition of metallic aluminium.

Faria, Erica N; Douglas, Samuel P; Mrig, Shreya; Santoni, Leonardo; Clancy, Adam J; Wilson, Daniel W N; Knapp, Caroline E · Nat Commun · 2025

basic_science · Level V

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Abstract

The development of microelectronics prompts a search for precursors that can deposit conductive features. There is scarce research on Al as it is normally deposited using pyrophoric AlH<sub>3</sub> etherates/aminates. Ligands can impart increased stability while maintaining the ability to deposit target materials. Accordingly, we have engineered an aluminium complex that can undergo conversion to Al(0) at 100 °C. Our multi-step synthetic design features β-ketoiminate compounds, [Al(R-ketoiminate)<sub>2</sub>Cl] (R = Me, Et, <sup>i</sup>Pr, Ph and Mes, 1-5) as starting materials to obtain aluminium hydride complexes: the polymeric amidoalane Li[AlH<sub>2</sub>(<sup>i</sup>Pr-Hacnac)AlH<sub>3</sub>]<sub>n</sub> (6) and the imidoalane cluster [AlH<sub>2</sub>AlH<sub>2</sub>(N-Mes)<sub>3</sub>(AlH<sub>2</sub> ּ Li(Et<sub>2</sub>O)<sub>2</sub>)<sub>2</sub>] (8). Decomposition of 8 into aluminium metal is observed when heated under vacuum at 100 °C and is confirmed by XRD, TEM, XPS. Deposition of a highly conductive film of Al is achieved from 8 after three weeks under nitrogen at room temperature. This represents a route to metallic aluminium involving non-pyrophoric precursors at low temperatures.