Ion beam synthesis of yttrium silicides in (111)Si

Abstract

Formation of yttrium silicides in 170 keV, 4 × 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 YSi 2 layer, about 35 nm in thickness, was found to form beneath a 30 nm thick polycrystalline layer. Preferential growth of YSi 2 with [001] YSi 2 ∥[111]Si was found to be the dominant mode of YSi 2 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°C for 1 min, a continuous silicide layer, about 100 nm in thickness, was found to form at the surface of the samples. The YSi 2 was found to agglomerate in samples annealed at 1000–1100°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 α-implanted and annealed samples.