Marker experiments for diffusion in the silicide during oxidation of PdSi, Pd2Si, CoSi2, and NiSi2 films on 〈Si〉

Abstract

Inert markers (evaporated tungsten and ion implanted Xenon) were used to investigate the mass transport through a silicide layer on a 〈Si〉 substrate during thermal oxidation at 700–900 °C. The SiO2 growth from PdSi, Pd2Si, CoSi2, and NiSi2 films on 〈Si〉 is a process limited by the diffusion of the oxidant from the ambient gas to the silicide/oxide interface. Possible diffusion processes through the silicide that supply Si to the growing SiO2 layer, but keep the silicide stoichiometry intact, are discussed. Backscattering spectrometry is used to monitor the marker position in the silicide layer. We find that the diffusing species during oxidation correlate with the moving species during silicide formation.