Reactor-scale models for rf diode sputtering of metal thin films

• Published in: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films Surfaces, and Films, 1999-07, Vol.17 (4), p.1926-1933
• Main Authors: Desa, S., Ghosal, S., Kosut, R. L., Ebert, J. L., Abrahamson, T. E., Kozak, A., Zou, D. W., Zhou, X., Groves, J. F., Wadley, H. N. G.
• Format: Article
• Language: English
• ISSN: 0734-2101; 1520-8559
• DOI: 10.1116/1.581705

This article describes the development of an integrated physical model for the rf diode sputtering of metal thin films. The model consists of: (1) a computational fluid dynamic finite element model for the velocity and pressure distribution of the working gas Ar flow in the chamber, (2) a steady-state plasma model for the flux and energy of Ar ions striking the target and the substrate, (3) a molecular dynamics sputtering model for the energy distribution, angle distribution, and yield of the sputtered atoms (Cu) from the target, and (4) a direct simulation Monte Carlo (DSMC) model for the transport of Cu atoms through the low-pressure argon gas to the deposition substrate. The individual models for gas flow, plasma discharge, Cu sputtering, and DSMC-based Cu atom transport are then integrated to create a detailed, steady-state, input–output model capable of predicting thin-film deposition rate and uniformity as a function of the process input variables: power, pressure, gas temperature, and electrode spacing. Deposition rate and uniformity in turn define the characteristics of thin films exploited in applications, for example, the saturation magnetic field for a giant magnetoresistive multilayer. This article also describes the development of an approximate input–output model whose CPU time is several orders-of-magnitude faster than that of the detailed model. Both models were refined and validated against experimental data obtained from rf diode sputtering experiments.