Formation and characterization of ultra-thin Ni silicides on strained and unstrained silicon

Ultra thin Ni-silicides were formed on silicon-on-insulator (SOI) and biaxially tensile strained Si-on-insulator (SSOI) substrates. Epitaxial NiSi2 layers were formed with a 3 nm Ni layer at T>400°C, while a polycrystalline NiSi layer was with a 5nm thick Ni layer. The NiSi2 layer quality advances with increasing temperature. A very thin Pt interlayer, to incorporate Pt into NiSi, forming Ni1-xPtxSi, improves the thermal stability, the interface roughness and lowers the contact resistivity. The Schottky barrier heights (SBH) of these silicides were measured on n-Si(100). Ni1-xPtxSi shows the highest SBH. The SBH of NiSi2 layers decreases by improving the layer interface. Surprisingly, the contact resistivity of epitaxial NiSi2 is about one order of magnitude lower than that of NiSi on both, As and B doped SOI and SSOI, The lowest value of 7×10⁻⁸ Ω cm² was measured on B doped SSOI.