Manganese half-sandwich complexes as metal-organic chemical vapor deposition precursors for manganese-based thin films

The synthesis of compounds [Mn(η5-C5H4SiMe3)(CO)3] (1), [Mn(η5-C5H3-1-SiMe3-3-Me)(CO)3] (2), [Mn(η5-C5H4tBu)(CO)3] (3), [Mn(η5-C5Me5)(CO)3] (4) and [Mn(η5-C5H7)(CO)3] (5) and their potential use as metal-organic chemical vapor deposition (MOCVD) precursors for the deposition of manganese-based layers is reported. The thermal behavior of 1-5 was studied by thermogravimetry showing that these compounds evaporate in the temperature range of 363-498 K depending on the cyclopentadienyl substituents and the type of pentadienyl used. Vapor pressure measurements indicate that all compounds possess vapor pressures between 60 and 630 Pa at 353 K. Compounds 1-5 could be successfully applied in manganese-based film deposition without activation steps prior to the MOCVD experiments. The as-deposited thin layers were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and X-ray powder diffraction. Under comparatively mild conditions, whereas 5 possesses the lowest deposition temperature (553 K), dense and conformal layers with growth rates up to 7.0 nm min− 1 (5) could be deposited. Metal carbonyls 1 and 2 featuring a SiMe3 group produced Si-containing manganese-based films. The as-deposited layers from 1, 2, 4 and 5 contain carbon impurities (5-8.9 mol-%), while the films from 3 are carbon-free. The layers from 1 and 2 consist of mainly manganese silicate and manganese oxide, whereas those obtained from 3 to 5 are composed of manganese oxides.