Elaboration and characterisation of yttria psz coatings deposited by RF sputtering on silicon

Abstract

Yttria stabilised Zirconia coatings on polycrystalline silicon wafers have been performed using physical vapor deposition with negative bias applied to the substrate. The thicknesses determined by ellipsometry were between 45 and 70 nm and the deposition rate was about 0.25 nm per min. Secondary ion mass spectroscopy analyses revealed no interdiffusion of metallic elements between the zirconia coating and silicon substrate. Grazing incidence X-ray diffraction indicates that the coatings are crystallized, but it can not permit to identify all the crystalline phases. The disparity between the experimental and the k-ratios (Pouchou and Pichoir simulation of electron probe microanalysis analyses) showed the usefulness of others techniques to determine coating and interface compositions. Cross sectional transmission electron microscopy observations demonstrate an amorphous layer between the zirconia coating and the substrate with a thickness of 30–120 nm. If it is considered to be an amorphous silicon layer, the PAP simulation based on the ellipsometric thicknesses and an yttria stabilised zirconia density of 4 g/cm³ fits correctly the experimental values.