Buried single-crystal CoSi2 layers in SiGe alloys made by ion beam synthesis

The synthesis of buried CoSi2 layers in Si0.91Ge0.09 alloys by the implantation of high doses of 100 and 150 keV Co+ ions and subsequent rapid thermal annealing at T≥1000 °C is studied by x-ray diffraction, Rutherford backscattering spectroscopy, He ion channeling, Auger electron spectroscopy, and transmission electron microscopy. After annealing, a buried single-crystal CoSi2 layer containing ≊1 at. % Ge is formed in the SiGe alloy. Silicide formation causes an outdiffusion of Ge leading to an increase in the Ge concentration of the adjacent SiGe layers. The remaining Ge within the silicide layer is found to be present as Si-Ge islands with the composition of the virgin Si0.91Ge0.09 alloy.