The thermodynamic and structural stability of ruthenium-manganese diffusion barriers on SiO2 is assessed. A ∼2 nm film composed of partially oxidized manganese (MnOx where x < 1) was deposited on a 3 nm thick Ru film and the Mn-MnOx/Ru/SiO2 structure was subsequently thermally annealed. X-ray photoelectron spectroscopy and secondary ion mass spectroscopy studies suggest the release and upward diffusion of Si from the dielectric substrate as a result of manganese-silicate formation at the Ru/SiO2 interface. The migration of Si up through the Ru film results in further manganese-silicate formation upon its interaction with the Mn-MnOx deposited layer. © 2013 AIP Publishing LLC.