Mechanical Properties of Au Films on Silicon Substrates

This paper presents the results of recent studies of the effects of film thickness on the mechanical properties of electron-beam (e-beam) deposited Au films on silicon substrates. Following a brief description of film microstructure and surface topography, film mechanical properties (Young's modulus and hardness) are determined using nanoindentation techniques. The effects of stiff silicon substrates on the Young's modulus are analyzed within the framework established by King [6 King , R.B. Elastic analysis of some punch problems for a layered medium . Inst. J. Solids Structures 1987 , 23 ( 142 ), 1657 – 1664 .[Crossref], [Web of Science ®] , [Google Scholar] 8 Saha , R. ; Nix , W.D. Effects of the substrate on the determination of thin film mechanical properties by nanoindentation . Acta Materila 2002 , 50 ( 1 ), 23 – 28 .[Crossref], [Web of Science ®] , [Google Scholar]]. The effects of indentation size on film hardness are also explained within the context of strain gradient plasticity theories and substrate effects. The plasticity length scale parameters are shown to scale with film thickness. The amount of material pile up is also shown to increase with decreasing film thickness, for a given ratio of indentation depth to film thickness. The implications of the work are discussed for applications of Au films on silicon substrates.