Ultrathin Ni Silicides With Low Contact Resistance on Strained and Unstrained Silicon

摘要

Ultrathin Ni silicides were formed on silicon-on-insulator (SOI) and biaxially tensile strained SOI (SSOI) substrates. The Ni layer thickness crucially determines the silicide phase formation: With a 3-nm Ni layer, high-quality epitaxial $hbox{NiSi}_{2}$ layers were grown at temperatures $>hbox{450} ^{circ}hbox{C}$, while NiSi was formed with a 5-nm-thick Ni layer. A very thin Pt interlayer, to incorporate Pt into NiSi, improves the thermal stability and the interface roughness and lowers the contact resistivity. The contact resistivity of epitaxial $hbox{NiSi}_{2}$ is about one order of magnitude lower than that of a NiSi layer on both As- and B-doped SOI and SSOI.