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Aluminum Dihydride Complexes and their Unexpected Application in Atomic Layer Deposition of Titanium Carbonitride Films

preprint
submitted on 02.05.2018 and posted on 03.05.2018 by Kyle J. Blakeney, Philip D. Martin, Charles H. Winter

Aluminum dihydride complexes containing amido-amine ligands were synthesized and evaluated as potential reducing precursors for thermal atomic layer deposition (ALD). Highly volatile monomeric complexes AlH2(tBuNCH2CH2NMe2) and AlH2(tBuNCH2CH2NC4H8) are more thermally stable than common Al hydride thin film precursors such as AlH3(NMe3). ALD film growth experiments using TiCl4 and AlH2(tBuNCH2CH2NMe2) produced titanium carbonitride films with a high growth rate of 1.6-2.0 Å/cycle and resistivities around 600 μΩ·cm within a very wide ALD window of 220-400 °C. Importantly, film growth proceeded via self-limited surface reactions, which is the hallmark of an ALD process. Root mean square surface roughness was only 1.3 % of the film thickness at 300 °C by atomic force microscopy. The films were polycrystalline with low intensity, broad reflections corresponding to the cubic TiN/TiC phase according to grazing incidence X-ray diffraction. Film composition by X-ray photoelectron spectroscopy was approximately TiC0.8N0.5 at 300 °C with small amounts of Al (6 at%), Cl (4 at%) and O (4 at%) impurities. Remarkably, self-limited growth and low Al content was observed in films deposited well above the solid-state thermal decomposition point of AlH2(tBuNCH2CH2NMe2), which is ca. 185 °C. Similar growth rates, resistivities, and film compositions were observed in ALD film growth trials using AlH2(tBuNCH2CH2NC4H8).

Funding

BASF Corporation, U.S. National Science Foundation

History

Email Address of Submitting Author

blakeney@chem.wayne.edu

Email Address(es) for Other Author(s)

chw@chem.wayne.edu

Institution

Wayne State University

Country

United States

ORCID For Submitting Author

0000-0002-0375-0056

Declaration of Conflict of Interest

No conflict of interest

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