ION-BEAM SYNTHESIS OF YTTRIUM SILICIDES IN (111)SI

Formation of yttrium silicides in 170 keV, 4 X 10(17)/cm(2) Y+-implanted (111) Si has been investigated by transmission electron microscopy, X-ray diffraction and Auger electron spectroscopy. A continuous buried YSi2 layer, about 35 nm in thickness, was found to form beneath a 30 nm thick polycrystalline layer. Preferential growth of YSi2 with [001] YSi2 parallel to [111]Si was found to be the dominant mode of YSi2 growth. A high density of twins and stacking faults was observed to distribute in the layer beneath the silicide layer. In samples annealed at 800 degrees C for 1 min, a continuous silicide layer, about 100 nm in thickness, was found to form at the surface of the samples. The YSi2 was found to agglomerate in samples annealed at 1000-1100 degrees C for 1 min. A high density of defects remained beneath the original silicide/Si interface. The silicide maintained the epitaxial relationships with respect to the substrate. No sign of vacancy ordering was detected from examination of diffraction patterns of all as-implanted and annealed samples.