The formation of metallic silicides of Ti, Y, Fe, Mo and W using metal vapour vacuum arc implantation

Abstract

The formation of metallic silicides was studied using implantation into Si with ions of Ti, Y, Fe, Mo and W produced by a metal vapour vacuum arc ion source. The electrical properties were measured by four-probe and spread-resistance probe devices. The resistivities are from tens to hundreds of micro-ohm centimetres for the implantation of these ions. The resistivity of Ti-, Y- and Fe-implanted layers decreased obviously with increasing ion flux. In contrast, the lowest resistivity is found for Mo and W implantations at 50 μA cm -2 . The glossy surface changes into a rough surface and the resistivity increases, if the ion flux of Mo and W is larger than 75 μA cm -2 . The silicide phases were distinguished by X-ray diffraction and Rutherford backscattering spectrometry. The metallic silicides TiSi, TiSi 2 , YSi, YSi 2 , FeSi, FeSi 2 , MoSi 2 and WSi 2 were fully formed if the ion flux was as high as 50 μA cm -2 . The surface atomic ratio was about 40%–60% for Ti, Y and Fe, and 20%–25% for Mo and W, if implanted doses of (3–5) × 10 17 cm -2 were used. The distribution depth of the silicides was about 30–80 nm. The new process technique is suitable and can be employed for shallow junction technologies of very-large-scale integration.