Abstract: Buried yttrium-silicide layer has been formed by ion implantation of Y into silicon (111) wafer and thermal annealing. Transmission electron microscopy shows that a continuous YSi₂ layer is buried on silicon substrate. The orientation relationship between YSi₂ and silicon is determined as 001YSi₂//111Si. Meanwhile, no sign of vacancy ordering was detected from examination of diffraction patterns of all as-implanted and annealed samples.