Ambient Effects on Thin Film Interactions

Abstract

ABSTRACTThin film interactions often show strong dependence on the annealing ambients used. The outdiffusion of a large number of metals and semiconductors through an overcoating gold film and subsequent formation of surface oxides have been observed to be greatly enhanced using a steam or air ambient compared with those using vacuum or inert ambients. The ambient effects become more puzzled when the overcoating metal consists of gold and silver layers, depending on the sequence of these layers. These ambient effects are shown to be well correlated by a surface potential model which considers both the relation between the overcoating metal and the underlying diffusing species, and the effects of ambient on the surface properties of the overcoating metal at the interface. Further ambient effects have been predicted and confirmed, including reduced interactions by oxygen for many systems with different overcoating metals. Different interaction mechanisms have also been observed, including competing ambient effects, competing interactions, and preferential reactions, all affected by the ambients used. Understandings of the various ambient effects not only provide important insights into the interface interactions in general, but also have great impact on metallurgical contacts in device technologies. Future studies for the ambient effects are also discussed.