Surface Studies of Aluminum Mitride Thik Films

Abstract

ABSTRACTThe nature and the composition of the surface and near surface region of A1N films plays a significant role in determining their chemical and thermal stability. A1N thin films were deposited by reactive RF magnetron sputtering of Al in argon and nitrogen atmosphere. Transmission and scanning electron microscopy indicated that these films have a dense columnar microstructure with columns oriented along the c-axis of the A1N crystallites. X-ray photo-electron spectroscopy (XPS) revealed a graded oxygen-rich surface layer about 5–10 nm thick which is formed when the film is exposed to the atmosphere. This oxide is limited to the surface and does not grow even when the film is annealed at 600°C for 10 hours in dry oxygen. It is expected that this passivating oxygen rich surface layer will, to a large extent, determine the oxidation resistance of the fresh underlying AIN. A surface chemistry model is proposed for this protection behavior.