An integrated circuit device, and a method of manufacturing the same, including nickel silicide on a silicon substrate fabricated with an iridium interlayer. In one embodiment the method comprises depositing an iridium (Ir) interface layer between the Ni and Si layers prior to the silicidation reaction. The thermal stability is much improved by adding the thin iridium layer. This is shown by the low junction leakage current of the ultra-shallow junction, and by the low sheet resistance of the silicide, even after annealing at 850° C.