Study of texture effect on elastic properties of Au thin films by X-ray diffraction and in situ tensile testing D. Faurie * , P.-O. Renault, E. Le Bourhis, Ph. Goudeau Laboratoire de Me ´tallurgie Physique, Unite ´ Mixte de Recherche, 6630 Centre National de la Recherche Scientifique, Universite ´ de Poitiers, BP 30179, 86962 Futuroscope, France Received 28 February 2006; received in revised form 9 May 2006; accepted 17 May 2006 Available online 21 August 2006 Abstract The influence of texture on the elastic behavior of Au thin films has been quantified experimentally and theoretically. The elastic behaviors of non-textured and {1 1 1} fiber-textured gold thin films were studied by in situ tensile testing using four-circle goniometers on a synchrotron beam line (LURE facility, France). The mechanical coupling of the substrate–thin film composite structure has been described and analytical solutions for diffraction strain analysis have been developed including texture and grain interaction models. These are applied to extract and compare elastic properties of the two types of gold films, and to quantify the effect of texture on the direction-dependent Young’s modulus. Ó 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Keywords: Thin films; Tension test; X-ray diffraction (XRD); Texture; Elastic behavior 1. Introduction Mechanical properties of thin films have received consid- erable attention because of their length-scale dependence and the implications for the reliable operation of microelec- tronic and microelectromechanical systems [1–3]. Decreas- ing the sizes of structures implies a control of elaboration processes at very small scales. The small dimensions, inter- faces and singular structures are intrinsic to thin films. Thus, in the light of ongoing efforts to reduce characteristic feature sizes in such systems, it is imperative to study the mechanical properties of materials at small scales. Materials are often assumed to behave uniformly, exhib- iting equal strength in all directions, because most of them have a polycrystalline structure. However, the anisotropy of individual crystals is smoothed out only in the presence of a large number of grains having a random distribution of orientations. Actually, a macroscopic anisotropy usually remains due to the existence of preferred orientations. Its magnitude depends upon the statistical distribution of grain orientations, i.e. the ‘‘crystallographic texture’’, more simply called the texture. This governs the extremes that a single crystal of the material under consideration can exhi- bit during directional tests. Polycrystalline thin films fabricated by sputtering meth- ods generally show textures that may be very strong [4]. Particularly, {1 1 1} texture is often encountered in the case of face-centered cubic (fcc) materials such as gold. For elas- tically anisotropic materials, texture induces macroscopic elastic anisotropy whose amplitude depends both on the degree of texture and on the elastic anisotropy of the crys- tallites that compose the polycrystalline thin films (local anisotropy). In many cases, macroscopic elastic anisotropy is very high and cannot be neglected. In order to study elastic properties of thin films, synchro- tron X-ray diffraction combined with in situ tensile testing is a very powerful technique [5,6]. Diffraction is a non- destructive tool, which allows for a selective assessment of 1359-6454/$30.00 Ó 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.actamat.2006.05.036 * Corresponding author. Present address: Netherlands Institute for Metals Research, Department of Materials Science and Technology, Rotterdamseweg 137, 2628 AL Delft, Netherlands. Tel.: +31 15 278 22 34; fax: +31 15 278 67 30. E-mail address: D.Faurie@tnw.tudelft.nl (D. Faurie). www.actamat-journals.com Acta Materialia 54 (2006) 4503–4513