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

Abstract

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 363–498K depending on the cyclopentadienyl substituents and the type of pentadienyl used. Vapor pressure measurements indicate that all compounds possess vapor pressures between 60 and 630Pa at 353K. 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 (553K), dense and conformal layers with growth rates up to 7.0nmmin−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 (5–8.9mol-%), 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.