Effect of a Ge interlayer on the high-temperature behavior of NiSi films

The effect of a thin Ge interlayer on the formation of Ni silicides on (100)Si substrates has been investigated. X-ray diffraction shows a remarkable increase of the nucleation temperature of NiSi2 in the presence of the Ge interlayer. Four-probe measurements show that the sheet resistance of silicide formed in Ni∕Ge∕Si system remains stable up to 850 °C, while the sheet resistance of silicide formed in Ni∕Si system presents a significant increase at 750 °C. Scanning electron microscopy indicates that island formation is not observed in the NiSi film grown on Ge∕Si substrate annealing at 800 °C. The classical nucleation theory is employed to explain the increased temperature of the nucleation of NiSi2 in the Ni∕Ge-Si system.