COMPARISON OF MECHANICAL-PROPERTIES OF TIN THIN-FILMS USING NANOINDENTATION AND BULGE TEST

Two experimental techniques including the bulge test and depth sensing nanoindentation measurements were used to describe mechanical propert ies of titanium nitride (TiNx) thin films in terms of their growth mor phology. Thin layers of titanium nitride (t = 400-700 nm) were deposit ed in a RF magnetron sputtering system on the Si(100) wafers containin g a layer of low stress (LPCVD) silicon nitride. Variation of the Youn g's modulus, hardness, and residual stresses of the TiNx films versus deposition parameters such as the substrate bias voltage and nitrogen partial pressure was investigated. It was found that, in particular, t he tensile residual stress of the films first increases with the subst rate bias to a maximum, then drops to zero and converts to the compres sive stress, that grows again with the negative bias. At the same time , both modulus and hardness monotonously rise with the substrate bias without any abrupt changes. The nanoindentation data extracted from dy namically loading-unloading of TiN films converged to the bulge test m easurements for compact coatings, but diverged from the bulge test dat a for porous coatings. The morphology of the films were observed using scanning electron microscopy and the relationships from dynamically l oading-unloading of TiN films converged to the bulge test measurements for compact coatings, but diverged from the between microstructural e volution of columns and mechanical properties of coatings are discusse d in terms of deposition parameters. (C) 1998 Elsevier Science S.A. Al l rights reserved.