Molecular Insights into Oxime-Containing Group 4 Transition Metal Precursors for Atomic Layer Deposition

In this article, we synthesized six organometallic precursors possessing oxime ligands, <i>tert</i>-butyl methyl ketone oxime (tmoxH), as potential precursors for atomic layer deposition (ALD). Homoleptic complexes, Ti(tmox)₄ (<b>1</b>), [Zr(tmox)₄]₂ (<b>2</b>), and [Hf(tmox)₄]₂ (<b>3</b>), and cyclopentadienyl (Cp)-functionalized heteroleptic complexes, CpTi(tmox)₃ (<b>4</b>), CpZr(tmox)₃ (<b>5</b>), and CpHf(tmox)₃ (<b>6</b>) were characterized through nuclear magnetic resonance (NMR), Fourier-transform IR spectroscopy (FT-IR), and single-crystal X-ray diffraction (SC-XRD). Thermogravimetric analysis was conducted to evaluate the thermostability of the newly synthesized complexes for ALD applications as metal precursors. Furthermore, ALD studies revealed that CpZr(tmox)₃ is a potential precursor that can modulate defect density and phase structure of thin films by controlling the deposition temperature. We also compared the ALD behaviors between amidoxime complexes and oxime complexes and observed the functional group effects on surface adsorption.