Influence of deposition pressure, substrate temperature and substrate outgassing on sorption properties of Zr–Co–Ce getter films

Abstract

Ultrahigh-vacuum conditions for microelectromechanical systems (MEMS) packaging can be achieved and sustained using a nonevaporable getter (NEG) film technology. Better understanding of the processes involved in film deposition, activation, and poisoning could help optimization and engineering of the film properties. In the present work, highly porous ZrCoCe films were deposited on (100) silicon substrates by direct current magnetron sputtering. Film morphology and performance dependence on deposition pressure, substrate temperature and substrate outgassing were investigated. The studies reveal that the pressure of the Ar sputtering gas affects significantly the film structure. High working pressures produce open columnar structures, whereas low pressures produce dense layers. It is demonstrated that the variation of the substrate temperature results in a significant modification of the film morphology. The highest sorption speed obtained for substrate temperature of 150 °C, is clearly correlated with the high specific surface area and porosity of the ZrCoCe film. It has also been confirmed that sorption properties can be improved by substrate outgassing prior to deposition.