The introduction of alternative process gas regimes during the reactive sputter deposition of titania coatings

Onifade, Ayokola A. and Kelly, Peter (2007) The introduction of alternative process gas regimes during the reactive sputter deposition of titania coatings. In: Tenth International Conference on Plasma Surface Engineering, 10th September 2006 - 15th September 2006, Garmisch-Partenkirchen, Germany.

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Abstract

TiO2 films are widely used as high refractive index dielectric layers in multilayer optical devices and functional films. The optical properties of titania films, and their stability, are critically dependent on the film structure, which in turn, is dependent on the deposition conditions used. In this study, titania films were grown by reactive pulsed magnetron sputtering in a dual variable field strength planar magnetron system. The effect of deposition conditions, including the use of alternate process gas regimes incorporating nitrogen, on film properties was investigated. Studies showed that the hysteresis behaviour of the Ti/O2 system was progressively reduced as the proportion of nitrogen in the process gas was increased. RBS analysis determined, though, that even for process gas regimes with equal flow rates of nitrogen and oxygen, no nitrogen could be detected in the films. Improvements were also noted in the wear resistance of the coatings deposited under these conditions, without any detrimental effect on their optical properties. Thus, the alternative process gas regimes explored here offer the potential for enhanced process control and improved coating durability during the reactive sputter deposition of titania films.