Agglomeration behavior of Ag films suppressed by alloying with some elements

Agglomeration behavior of co-sputtered Ag–Au, Ag–Cu and Ag–Al thin films was investigated. The results showed that Ag–Au films agglomerated during annealing in a similar way to pure Ag films, but a degree of suppression of this effect was observed in Ag–Cu and Ag–Al films. In particular, no void formation was observed in Ag–Al films for annealing temperatures up to 600 °C. Different mechanisms are proposed to explain agglomeration suppression and the prevention of Ag atom migration, including the precipitation Cu atoms in Ag–Cu films, and the formation of very thin Al-oxide layers at the film surface and at the interface with the substrate. The resistivity of Ag–Au film increased by annealing due to the agglomeration, but that of Ag–Cu and Ag–Al films did not. However, the resistivity of as-deposited Ag–Al film was too high to be reduced enough by annealing.