Structural properties of Y2O3 thin films grown on Si(1 0 0) and Si(1 1 1) substrates

Y2O3 thin films were deposited by radio frequency (rf) magnetron sputtering on Si substrates. The influence of the deposition parameters – substrate temperatures and post-annealing treatment – on the structural properties is studied by X-ray diffraction (XRD) technique, ellipsometric measurements, transmission electron microscopy (TEM) and atomic force microscopy (AFM) observations. The Y2O3 layers with (1 1 1) oriented growth perpendicular to the film surface have been obtained on the Si(1 1 1) as well as on the Si(1 0 0) substrates. TEM observations reveal an existence of voids in the polycrystalline Y2O3 layers probably originating from the interaction of the metalllic Y layer with the SiO2 native layer. The layers consist of randomly oriented grains in the film plane with a maximum size of 30 nm. The existence of the voids has also been proved by ellipsometric evaluations. The expected improvement of the structural properties such as better crystallinity and surface smoothness has not been registered upon post-deposition annealing treatment. The information about the microstructure of the Y2O3 films will be used to assess the suitability of this material for high-κ gate dielectric applications.