Synthesis, Characterization, and Thermal Properties of Liquid Iron Amidinates and Their Potential as Chemical Vapor Deposition Precursors for Producing Iron-Containing Films

Chemical vapor deposition (CVD) has become a favorable method for preparation of iron-containing films. However, as a key role in the CVD process, the available liquid iron precursor is scarce. To this aim, this study synthesized two liquid iron complexes using sec-butyl-containing amidines as ligands, and the synthesized complexes’ structures were characterized through ¹H NMR spectroscopy and elemental analysis. Thermogravimetric analysis (TGA) was employed to study the thermal properties (including volatility, thermal stability, and vapor pressure) of the designed complexes, and the results demonstrated that both complexes have excellent volatility, sufficient thermal stability and vapor pressure. The reactivity of the complexes was observed through solution reactions between them and conventional co-reagents, and both complexes exhibited high reactivity. Moreover, the applicability of the synthesized complexes as CVD precursors were evaluated through film deposition experiment, and a continuous, uniform, high purity, and smooth α-Fe₂O₃ film was obtained. These results demonstrated that the synthesized complexes are promising precursors for the CVD of iron-containing films.