Monte-Carlo simulation of ionisation in self-induced ion plating (SIIP)

SIIP can be defined as the evaporation of a metallic target thanks to ion bombardment of a magnetron sputtering system. A numerical simulation model of the SIIP process has been already realized [A. Contino, V. Feldheim, P. Lybaert, B. Deweer, H. Cornil, October 2005, Modelling of continuous steel coating by self-induced ion plating (SIIP), Surface and Coatings Technology, Vol. 200, Issue 1–4, pp.898–903] in order to predict the thickness profile of the coating. The model was constituted of three coupled submodels: a magnetic model, a heat transfer model and an evaporation model. The comparison between the simulated results and the measurements showed that our results did not perfectly agree with the experimental values. This could be explained by the difficulty in doing the accurate measurements but also by simplifying assumptions introduced into the model. The purpose of the present work is to remove one of these assumptions: the use of a non-validated power law [Plasma Surface Engineering Corporation, Technology Note: Magnetron sputtering, Feb. 2003. ] to evaluate heat flux distribution (due to ion bombardment) on the target. To obtain an accurate ion bombardment heat flux distribution we compute the ions strike points distribution on the target surface using a Monte-Carlo method [T.E. Sheridan, M.J. Goeckner, and J. Goree, 1990. Model of energetic electron transport in magnetron discharges, J. Vac. Sci. Technol. A8(1) 30–37] and we assume that the heat flux is proportional to the number of ions colliding with the target. The computed heat distribution is compared with the power-law distribution used previously. The new distribution is more accurate and will be implemented in the future in the numerical simulation model previously developed to predict coating thickness.