Stress evolution of Ni /Pd /Si reaction system under isochronal annealing

Abstract

The stress evolutions of Ni /Pd /Si samples under isochronal annealing condition were studied. We have used a laser scanning method for substrate curvature measurements to measure the total force per unit width ( F/W) of the film produced during isochronal annealing. With the introduction of a thin Pd interlayer into the Ni /Si reaction system, the curve of F/W versus temperature shows two additional abrupt changes, one is associated with the formation of the Pd 2Si phase and the other is associated with the initial stage of the Ni 2Si formation. With increasing thickness of the Pd interlayer (up to 5 nm), the temperatures for the complete formation of Ni 2Si and NiSi were increased, while the threshold temperature for the formation of NiSi 2 was not significantly changed. The thin Pd 2Si layer formed at low temperature acts as a diffusion barrier to retard the formation of Ni 2Si and subsequently delay the formation of NiSi. The maximum difference of the total force per width in the film, during the whole isochronal annealing process, was significantly reduced with increasing Pd layer thickness.