The First Non-Pyrophoric Precursor for the Low Temperature Deposition of Metallic Aluminium

Abstract The development of microelectronics prompts a search for precursors that can deposit conductive features. There is scarce research focusing on Al as it is normally deposited using pyrophoric and highly air- and moisture-sensitive AlH3 etherates or aminates. By careful consideration, ligands can impart increased stability while maintaining the ability to deposit the target materials. To this end, we have engineered an aluminium complex that can undergo reductant-free conversion to Al(0) at 100°C. Our strategy utilized multi-step synthetic design featuring β‑ketoiminate (acnac) bidentate ligands, [Al(R-acnac)2Cl] (R = Me, Et, iPr, Ph and Mes, 1-5) that were used as starting materials to obtain aluminium hydride complexes: the polymeric amidoalane Li[AlH2(iPr‑Hacnac)AlH3]n (6) and the imidoalane cluster [AlH2AlH2(N‑Mes)3(AlH2 ּ Li(Et2O)2)2] (8). When heated under vacuum at 100°C, 8 decomposes into aluminium metal, confirmed by XRD, TEM, XPS. This represents the first instance of a route to metallic aluminium involving non-pyrophoric precursors at low temperature.