The effect of argon plasma treatment on the structural and electrical properties of Ni silicides has been investigated. Electron-beam-evaporated Ni films on Si substrates are Ar plasma-treated by an inductively coupled plasma (ICP) reactor. For silicidation reactions, all the samples with and without the Ar plasma treatment are rapid-thermal annealed (RTA) at temperatures of 500–750°C in a nitrogen ambient. It is shown that the Ar plasma-treated samples produce better electrical and structural properties across the whole temperature range as compared with the untreated samples. It is further shown that the Ar plasma-treated samples contain nitrogen, which plays an important role in improving the morphological stability and the electrical properties of the silicide films.