Low temperature chemical vapor deposition of Co thin films from Co2(CO)8

Cobalt thin films were deposited on the Si(100) substrates with temperatures ranging from 60 °C to 250 °C using chemical vapor deposition with a metallorganic Co2(CO)8 precursor. After Ar sputtering of the surface of the films, X-ray photoelectron spectroscopy (XPS) showed negligible O peak for all samples investigated. Analysis of high-resolution XPS Co and C peaks showed that a Co-C bond exists at high deposition temperatures of 140 and 160 °C. But pure Co peaks with no Co carbide bonding were observed for films deposition at 70 and 80 °C. Two growth rate maxima were observed at substrate temperatures of 120 and 220 °C using the Rutherford backscattering spectrometry. The two maximum growth rates are due to the transition from surface reaction controlled growth (60 to 140 °C) to mass-transport controlled growth (150 to 220 °C). The decrease of growth rate after the maximum growth rate was believed to come from a change in the decomposition pathways and the sticking coefficient.