Projet de thèse en Physique des accélérateurs
Sous la direction de Marie-Christine Lepy et de Emmanuel Nolot.
Thèses en préparation à Paris Saclay , dans le cadre de Particules, hadrons, énergie et noyaux: Instrumentation, Imagerie, Cosmos et Simulation , en partenariat avec Institut CEA LIST (laboratoire) et de Université Paris-Sud (établissement de préparation de la thèse) depuis le 05-10-2015 .
Probing chalcogenide films by advanced X-ray metrology for the semiconductor industry
Novel chalcogenides materials (based on S , Se, Te) are receiving increasing interest, not only for advanced memory applications (Conductive Bridge RAM , Phase Change RAM), photonics and photovoltaic, but also around innovative 2D transition metal dichalcogenides (Mo, W) ( Se, S)2 . The performances of thin chalcogenide films grown by chemical vapor deposition (CVD) or magnetron sputtering (PVD) are highly driven by the chemistry of films, surfaces and interfaces. Hence adequate metrology needs to be developed able to probe these materials and interfaces. The objective of this PhD is to develop the advanced metrology protocols required to support the development of the novel chalcogenide materials and their integration in complex technological stacks. The chemical composition will be investigated using Wavelength Dispersive X-Ray Fluorescence (WD-XRF) and the composition profiles will be probed by combination of X-Ray Reflectometry (XRR), Grazing Incidence X-Ray Fluorescence (GI-XRF) and Angle-resolved X-ray Photoemission Spectroscopy (ARXPS). These in-depth investigations run on state-of-the-art tools will be complemented by fluorescence (GiXRF) and absorption (EXAFS , NEXAFS ) experiments at the SOLEIL/Metrology synchrotron line, through strong collaboration with the National Henri Becquerel Laboratory located in Saclay. The combination of Lab and synchrotron based metrology will allow detailed understanding of the chemistry of thin chalcogenides films and interfaces. The metrology protocols will be applied to the characterization of innovative films grown by CVD (ternay alloys, 2D transition metal dichalcogenides, etc). In addition, they will support the development of binary and ternary chalcogenides using co-sputtering technique. A thorough study of the impact of the PVD process parameters on the properties of chalcogenide films will be conducted: the influence of working pressure, power, gas flow rates and process temperature on the stoichiometry of the film will be evaluated to better understand the mechanisms of material deposition. Reactions at the interfaces will then be investigated so as to evaluate their impact on the local and average composition.