Thermal stability of Ni(Zr)Si silicide and Ni(Zr)Si/Si Schottky diode

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 (RTA) 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.