Modelling of reactive sputtering processes involving two separated metallic targets

A theoretical model is presented in order to predict general behaviours and properties of the reactive sputtering process implementing two separated metallic targets in a reactive atmosphere. Taking into account gas kinetic theory, geometrical characteristics of the device and from simple physical and chemical assumptions, the proposed theoretical development is capable of describing evolutions of some process parameters such as reactive gas partial pressure. Some relationships between reactive gas flow rate, gas pressure and sputtering rate coming from each target have been established. Theoretical results determined with this model have been compared with experimental measurements obtained for the titanium-chromium-oxygen system. It is pointed out the proposed model is quite convenient to predict whole behaviours of the multitarget reactive sputtering process. The 'characteristic function' has also been calculated leading on some original and interesting theoretical results: a new way to remove totally or to modulate the size and the position of the instability phenomena of the reactive method. (C) 1999 Elsevier Science S.A. All rights reserved.