A Hafnium interlayer method to improve the thermal stability of NiSi film

The effect of a thin Hafnium interlayer on the thermal stability of NiSi film has been investigated. Both X-ray diffraction and Raman spectra show that no high resistivity NiSi2 appears in the Hf-additioned films which were post-annealed at temperatures ranging from 600 °C to 800 °C. Auger electron spectroscopy and Rutherford back scattering show that the Hf interlayer has moved to the top of the film after rapid thermal annealing, working as the diffusion barrier for upper Ni atoms. The three-dimensional surface morphology by atom force microscopy shows that the agglomeration of NiSi is effectively suppressed, which is attributed to the barrier effect of the Hf interlayer. The fabricated Ni(Hf)Si/Si Schottky diodes still displays good current–voltage characteristics even after annealed at temperatures varied from 650 °C to 800 °C, which further show that the Hf interlayer can improve the thermal stability of NiSi.