Interface growth mechanism in Ion Beam Sputtering deposited Mo/Si multi-layers

• Published in: Philosophical magazine (Abingdon, England) Vol. 86; no. 19; pp. 2865 - 2880
• Main Authors: Largeron, Christophe, Quesnel, Etienne, Thibault, Jany
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 14.09.2006
• Subjects: Physical Sciences
• ISSN: 1478-6435; 1478-6433
• DOI: 10.1080/14786430600640502

Despite the technological importance of Metal/Si multilayer structure in Microelectronics, the interface reactions occurring during their preparation are not fully understood, yet. In this work, the interface intermixing in Mo/Si multilayer coatings has been studied with respect to their preparation conditions. Various samples prepared at room temperature with different Mo deposition rates (0.06-0.43 Å/s) and a constant Si one have been investigated by detailed TEM observations. Contrary to the Si-on-Mo interface where no evidence of chemical intermixing could be found, the Mo-on-Si interface presents a noticeable interface zone whose thickness was found to noticeably decrease (from 4.1 to 3.2 nm) when increasing the Mo deposition rate. Such intermixing phenomena correspond to diffusion mechanisms having coefficients ranging from 0.25 to 1.2.10-15 cm²/s at room temperature. By assuming a diffusion mechanism mainly driven by Mo-Si atomic exchanges to minimize the surface energy, the diffusion dependence with Mo deposition rate has been successfully simulated using a cellular automaton. A refined simulation including Mo cluster formation is also proposed to explain the scenario leading to the full crystallisation of Mo layers.