Improvement of CoSi2 thermal stability by cavity formation

We propose a method to improve the thermal stability of thin ${\mathrm{CoSi}}_{\mathrm{2}}$ layers on polycrystalline silicon substrates. Nitrogen atoms have been implanted at 55 keV to a dose of ${\text{5×10}}^{15}/{\mathrm{cm}}^{\mathrm{2}}$ through a 70 nm silicide layer in order to locate the implanted peak near the silicide/silicon interface. The large band of cavities created at the interface has extended the thermal stability window by 125 °C with respect to the standard process. The improvement has been related to the silicide grain-boundary pinning due to the increase of the interface free energy contribution.