Buried Silicide Synthesis and Strain in Cobalt-Implanted Silicon

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Abstract
Silicon (001) substrates were implanted with 350 keV co at room temperature and 450°C with fluence of from 1x1017 Co/cm2 to 6x10 Co/cm2. All samples were annealed at 1000°C in order to form the CoSi2 phase. Concentration profiles were determined with Rutherford backscattering spectrometry (RBS), and the associated strain profiles were analyzed with double-crystal X-ray rocking curve measurements. Ion channeling was also used to characterize.the suicide formation and crystal quality. An implantation of 6x1017 Co/cm2 at 450°C forms a single-crystal CoSi2 layer while lower fluences do not. A continuous, buried CoSi2 single-crystal layer is formed for the 3x1017 Co/cm2 sample implanted at 450°C and annealed at 1000°C. The continous CoSi2 layer is thicker than the critical layer thickness for a fully coherent film, and therefore the layer partially relaxes. A relaxation of 50% of the fully coherent value is observed for this buried suicide system.