Ultrathin homogeneous Ni(Al) germanosilicide layer formation on strained SiGe with Al/Ni multi-layers

Graphical abstract Homogeneous Ni(Al) germanosilicide layers are formed on strained SiGe.Ni5(SiGe)3 phase is identified.Al concentration and annealing temperature influence the formed germanosilicides.The optimized process also applies to Si0.55Ge0.45 with higher Ge content. We present a systematic investigation of the formation of Ni germanosilicide layers on strained SiGe/Si(100) substrates. Homogeneous Ni germanosilicide layers with smooth surface, sharp interface and low sheet resistance are obtained by annealing thin Al/Ni multi-layers on SiGe. The morphology, composition and sheet resistance of the germanosilicide layers are investigated as a function of Al percentage and annealing temperature. Best results of Ni germanosilicide layers are achieved at 400¿C with 20% Al on fully strained SiGe layers with Ge contents of 36at.% and 45at.%. The uniform layers show a Ni5(Si1-xGex)3 phase. The compressive strain in the remaining SiGe layer is conserved after germanosilicidation, providing uniform contacts for high hole mobility SiGe layers for device application.