Chemical Vapor Deposition of Manganese Metallic Films on Silicon Oxide Substrates

Abstract

The growth of manganese-based films on silicon oxide substrates via the thermal decomposition of two Mn metalorganic complexes, bis(N,N′-diisopropylpentylamidinato)Mn(II) and methylcyclopentadienylmanganese(I) tricarbonyl, was characterized and contrasted by using an instrument equipped with a reactor coupled to a X-ray photoelectron spectroscopy (XPS) analytical chamber. The acetamidinate precursor proved highly reactive, affording the deposition of Mn at reasonable rates, higher at higher temperatures, but also leading to the incorporation of approximately 15% of nitrogen and additional carbon in the grown Mn(0) films. The methylcyclopentadienyl compound, by contrast, proved quite unreactive, even if an electron-impact gas-phase preactivation step recently developed in our laboratory was used. Slow deposition rates were seen with this precursor, appearing to be slower at higher temperature because of an unfavorable kinetic competition with Mn diffusion into the bulk. In both cases, a nonstoichiometric mixture of MnOx + SiOx and Mn silicate is formed first, possibly followed by the formation of a thin subsurface Mn silicide layer. The combined Mn silicate/Mn silicide structure acts as an effective diffusion barrier, after which Mn(0) metallic films can be grown on top. The implications of this behavior to the design of Mn chemical vapor deposition processes are briefly discussed.