Homogeneous NiSi1−xGex layer formation on strained SiGe with ultrathin Ni layers

• Homogeneous germanosilicide layers are formed on strained SiGe.
• Ni layer thickness and annealing temperature influence the germanosilicide layer’s phase and morphology.
• Strain in remaining SiGe can be conserved with the optimized process.

Homogeneous nickel germanosilicide layers with low sheet resistance have been achieved on highly strained SiGe layers. The layer homogeneity improves with decreasing Ni thickness. Ultrathin Ni layers of 3 nm thermally treated at 400 °C yield to homogeneous germanosilicide layers with a preferential {0 1 0} growth plane and sharp interfaces to the SiGe layer. This is assumed to be energetically driven by lower surface and interface energies due to the increased surface/volume ratio with decreasing layer thickness. The strain in the remaining SiGe layers can be conserved at lower temperatures. However, at higher temperatures, germanosilicidation enhances the strain relaxation.

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