Kinetics of Adsorption of Methylcyclopentadienyl Manganese Tricarbonyl on Copper Surfaces and Implications for the Atomic Layer Deposition of Thin Solid Films

The kinetics of the thermal chemistry of methylcyclopentadienyl manganese tricarbonyl on copper surfaces was followed by infrared absorption spectroscopy analysis of the gas surrounding the substrate. Dissociative adsorption of the MeCpMn(CO)(3) precursor was seen at low temperatures, below 400 K, and was determined to occur via the initial loss of a single carbon monoxide ligand. Full decarbonylation was observed starting at a surface temperature of approximately 510 K, and full decomposition of the Mn precursor was seen to be complete by 540 K. All these transitions were determined to occur at temperatures at least 100 K lower. than those reported on silicon oxide surfaces. Comparison with reference spectra afforded the identification of the main hydrocarbon product as a mixture of methylcyclopentadiene isomers. Isothermal measurements of MeCpMn(CO)(3) partial pressure versus reaction time highlighted a deviation from first -order kinetics, an effect associated with changes in surface reactivity. A self-limiting regime typical of atomic layer deposition processes was identified between 475 and 525 K by the incomplete conversion of the precursor, which displayed similar reaction rate and reached the same asymptotic partial pressure at all temperatures within that temperature bracket. Higher surface temperatures promoted total precursor consumption, at a rate that increased with increasing surface temperature; an apparent activation energy of approximately 40 kJ/mol was estimated in that high-temperature regime. The resulting chemical-vapor deposited multilayers were identified by X-ray photoelectron spectroscopy to consist of MnO.