The improvement of thermal stability of nickel silicide by adding a thin Zr interlayer

This is the first report of a technique for inserting a thin Zr interlayer into a nickel film to improve the thermal stability of the silicide formed from this film. The sheet resistance of resulting Ni(Zr)Si film was lower than 2 Ω/□. X-ray diffraction and Raman spectral analysis showed that only the silicides low resistance phase (NiSi), rather than high resistance phase (NiSi2), was present in the sandwich structure. This proves that the incorporation of a thin Zr interlayer into NiSi delayed the occurrence of NiSi2 phase and widened the upper boundary of silicide formation window by about 100 °C. These experimental results could be explained by Gibbs free energy theory. Furthermore, Ni(Zr)Si/Si Schottky diodes were fabricated by rapid thermal annealing at 650, 700, 750 and 800 °C in order to study the I–V characteristics of the SBD diodes. The barrier height generally fixed at 0.63 eV, and the ideality factor was close to 1. These results show that Ni(Zr)Si film is a favorable local interconnection and contact silicide material.