High current Ni-ion implantation to synthesize NiSi 2 layers on Si with very low resistivity

Abstract

Metal Vapor Vacuum Arc (MEVVA) ion implantation was employed to synthesize NiSi 2 layers on Si(1 0 0) wafers and was conducted at a voltage of 45 kV with various current densities to a fixed dose of 2 × 10 17 ions/cm 2, required by the chemical stoichiometry. From a thermal expansion calculation, there would be no size mismatch between NiSi 2 and Si lattices at 380°C. A current density of 35 μA/cm 2 was required, according to an estimation, to heat the wafers to 380°C. Implanting with this selected current density, a unique NiSi 2 layer was indeed obtained with a resistivity as low as 14 ± 2 μΩ cm. Furthermore, a temperature dependence of the resistivity was observed and the NiSi 2 layers formed at temperatures deviated from the zero-mismatch temperature featured greater resistivities than that of the layer synthesized at 380°C. The experimental results are reported in detail together with a discussion of the observed temperature dependence.