Abstract
A thin interlayer of Ge (1.5, 3.0, 6.0 nm) or Ir (1.5, 3.0 nm) and the Ni thin film (30 nm) are deposited by the electron beam evaporation system on (001)Si substrates at room temperature. The formation and thermal stability of Ni silicides are characterized by in-situ curvature measurement, X-ray diffraction (XRD), Auger electron spectroscopy (AES), four-point probe method, high-resolution transmission electron microscopy (HRTEM), and transmission electron microscopy (TEM) with energy dispersive X-ray spectrometry (EDS).The maximum difference of force per width (F/W) in the film, during the reaction process of the nickel silicides, is reduced by the presence of the interlayer. With increasing thickness of the Ge interlayer, the process window for NiSi phase is increased and the NiSi2 nucleation is retarded. However, the process window for NiSi phase is shortened by the thin interlayer of Ir. With a 3 nm thick Ge interlayer, the thermal stability of NiSi is widened and the temperature for NiSi2 nucleation is delayed by 133℃and 95℃, respectively.In the case of Ni (30 nm)/Ir/ Si (001), we didn’t observe the Ni2Si phase. At high temperature annealing, the NiSi films which are unstable and agglomerative cause an increase in the values of sheet resistance.In the case of Ni (30 nm)/Ge/ Si (001), the Ni2Si phase is formed at lower temperature with Ge solubility in the phase. With increasing annealing temperature, the NiSi films is formed and Ge atoms probably stay at the defect sites or grain boundary of NiSi. The increase in thermal stability of NiSi can be explained by the fact that energy is required to expel Ge from newly nucleated NiSi2 phase.