Metal silicides synthesized by high current metal-ion implantation

High current metal-ion implantation by a metal vapor vacuum are ion source was conducted to synthesize some metal silicides, which are important candi dates as materials in microelectronics. It was found that C54-TiSi2, ZrSi2, NiSi2, CoSi2, beta-FeSi2, NbSi2, and TaSi2 layers on Si wafers with good e lectric properties could be obtained directly after implantation at relativ ely low formation temperature and that the formation of alpha-FeSi2, NbSi2 TaSi2, tetragonal WSi2, and tetragonal MoSi2 required additional postanneal ing to improve their crystallinity as well as their electric properties. In terestingly, NiSi2 layers of superior crystallinity and thus electric prope rty were obtained for the first time by Ni ion implantation with a selected current density of 35 mu A/cm(2), which heated the Si wafers to a specific temperature of 380 degrees C. Under such formation conditions, the lattice mismatch between the growing NiSi2 and the Si substrate was calculated to be zero. The resistivity of the NiSi2 layers obtained was much lower than t hat of the Ni disilicide synthesized by a solid-state reaction that require d a formation temperature of over 750 degrees C. The formation mechanism of the metal silicides studied and their associated electrical properties are also discussed. (C) 1999 American Vacuum Society. [S0734-211X(99)06905-X].