Interplay Between Grain Boundary Grooving, Stress, and Dealloying in the Agglomeration of NiSi1 − x Ge x Films

Germanosilicides, especially those formed on compressive substrates, are less stable than silicides against agglomeration. By studying the solid-state reaction of Ni thin film on strained Si 0.8 Ge 0.2 (001), we show that nickel germanosilicide is different from nickel silicide and nickel germanide in several respects: the grains are smaller and faceted, the groove angle is sharper, and dealloying takes place. The germanium out-diffusion creates a stress in the film which favors grooving and agglomeration.