Chemical vapor deposition of ruthenium oxide thin films from Ru(tmhd) 3 using direct liquid injection

Abstract

Direct liquid injection (DLI) of Ru(tmhd) 3 (tmhd=2,2,6,6-tetramethylheptane-3,5-dione) in n-butylacetate solvent was used to deposit ruthenium oxide and ruthenium thin films in the temperature range of 250–450 °C. Arrhenius plot showed that the mass transfer of the reactant determined the deposition rate at high temperature and it was determined by the surface reaction at lower temperature. Depending on the operating conditions, oxide phase, metal phase or mixed phase was obtained. At low O 2 flow rate and high injection rate of the precursor solution, the formation of ruthenium was preferred. For example, at the condition of the injection rate of 0.07 ml/min and O 2 flow rate of 300 sccm, ruthenium metal phase was deposited over 350 °C. At lower injection rate, ruthenium oxide films with low resistivity of approximately 45–60 μΩ cm were formed which showed dense and smooth surface morphology. At high deposition temperature, the resistivity of the film was increased due to the carbon incorporation.