| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Thin Films | Thursday Sessions |
| Session TF-ThM |
| Session: | Advanced Protective Coatings/Stress Evolution, Nanostructure, and Physical Properties of Thin Films |
| Presenter: | Jonathan Colin, Institut Pprime, CNRS-Université de Poitiers, France |
| Authors: | G. Abadias, Institut Pprime, CNRS-Université de Poitiers, France J. Colin, Institut Pprime, CNRS-Université de Poitiers, France C. Furgeaud, Institut Pprime, CNRS-Université de Poitiers, France A. Michel, Institut Pprime, CNRS-Université de Poitiers, France |
| Correspondent: | Click to Email |
The understanding of morphological and microstructural development during thin film growth is of particular relevance to control islands shape, nucleation and growth of nanoparticles, phase transformation, texture or surface roughness. Due to oversaturated vapour fluxes employed in physical vapor deposition (PVD) techniques, dynamics usually prevails over thermodynamics in dictating growth and microstructural evolution in PVD films. Depending on the material type and process conditions, the film can develop different stress levels, evolving usually with film thickness. Recently, real-time wafer curvature measurements have contributed to increase our knowledge on the underlying mechanisms of stress development during growth, and to propose comprehensive physical models [1].
In this presentation, we will provide some examples of in situ and real-time diagnostics based on optical techniques (wafer curvature, surface differential reflectance spectroscopy) and electrical resistance measurements to probe with high sensitivity the early growth stages of a variety of metal films on Si during sputter-deposition. We will first review some typical compressive-tensile-compressive stress evolutions observed for high-mobility metals (e.g. Ag, Cu, Au) [2]. The influence of interface reactivity (using different buffer layers- SiOx, a-Si or a-Ge ) will be highlighted, and for the specific case of Cu, alloying with Ge (using co-sputtering) will be addressed.
In the second part of the talk, special focus will be placed on low-mobility metal systems (e.g., Mo, Ta, W) deposited on amorphous Silicon (a-Si), which exhibit a complex stress development with film thickness. In the case of Mo and Fe films, our in situ measurements reveal a structural transition at a film thickness of ~ 2-3 nm manifested by a concomitant tensile stress variation [3] and decrease in electrical resistance. Insights on the kinetics of the amorphous-to-crystalline phase transformation were gained from in situ synchrotron studies, coupling simultaneously X-ray diffraction, X-ray reflectivity and wafer curvature during sputter-deposition of a series of Mo1-xSix alloys.
[1] E. Chason, P.R. Guduru, J. Appl. Phys. 119 (2016) 191101.
[2] G. Abadias, L. Simonot, J.J. Colin, A. Michel, S. Camelio, D. Babonneau, Appl. Phys. Lett. 107 (2015).
[3] A. Fillon, G. Abadias, A. Michel, C. Jaouen, P. Villechaise, Phys. Rev. Lett. 104 (2010) 096101.