A comparison between thermal annealing and ion mixing of multilayered Ni-W films on Si. II

Abstract

The reactions between bilayered Ni/W films and Si〈100〉 substrates induced by thermal annealing and ion mixing were investigated and compared. Samples were prepared by electron-beam sequential deposition of Ni and W onto the Si〈100〉 substrates and following by either furnace annealing (∼200-900 °C) or ion mixing (∼2×1015-4×101686Kr + ions/cm2). The reactions were analyzed by Rutherford backscattering and x-ray diffraction (Read camera). Thermal annealing of both W/Ni/Si〈100〉 and Ni/W/Si〈100〉 samples led to the formation of Ni silicide next to the Si substrate and W silicide on the sample surface (layer reversal between Ni and W in the Ni/W/Si〈100〉 case). Ion mixing of W/Ni/Si〈100〉 samples led to the formation of Ni silicide with a thin layer of Ni-W-Si mixture located at the sample surface. For Ni/W/Si〈100〉 samples a ternary amorphous mixture of Ni-W-Si was obtained with ion mixing. These reactions were rationalized in terms of the mobilities of various atoms and the intermixings between layers.