[en] Two differently structured WSi₂ phases were formed by direct W ion implantation, for the first time, into silicon wafers using a metal vapour vacuum arc ion source. Implantation of W ions was conducted with an extract voltage of 40 kV, various beam densities from 50 to 115 μA cm^-2 and a fixed dose of 5 x 10¹⁷ cm^-2. It was found that the formation of WSi₂ with either a hexagonal or a tetragonal structure depended on the ion current density. The temperature rise caused by beam heating and the beam-striking time related to the dose were calculated, and they were responsible for the formation and evolution related to the differently structured WSi₂ phases. (author)