N-induced cavity nucleation at the CoSi2/Si interface has been investigated for different doses and its influence on improving the thermal stability of the silicide layer up to 1075 °C has been detailed. The N-implant energy and doses have been chosen in such a way that the projected range (Rp) was near the interface and the underlying polycrystalline silicon substrate was completely amorphized. After a thermal treatment of 975 °C, it has been found that the cavity density depends on the dose, but the cavity size is dose independent. The cavity density should be enough to saturate the silicide grain boundaries but not so high to neglect ripening and coalescence. A density of 2.5×1010 cavities/cm2 has been measured at a nitrogen dose of 7×1015/cm2 corresponding to a partial saturation of the silicide grain boundaries and to the higher stability gain (150 °C). © 2002 American Institute of Physics.