Fully-depleted SOI CMOSFETs with the fully-silicided source/drain structure

A fully-depleted (FD) silicon-on-insulator (SOI) CMOSFET, whose source/drain (S/D) layers are completely silicided in depth with cobalt, have been successfully fabricated for the first time on a 20-nm-thick SOI layer using our advanced cobalt salicide technology. The fully-silicided S/D-nMOSFET and pMOSFET exhibit the same level of series resistance and significantly reduced bipolar junction transistor (BJT) action, compared to the conventional partially-silicided structure. The small series resistance is due to the small contact resistivity of CoSi₂ to both n⁺- and p⁺-diffusion layers, which are estimated to be on the order of low-10^-8 Ω-cm² and high-10^-8 Ω-cm², respectively. The improved BJT property is speculated to stem from the cobalt atoms diffused in the vicinity of the n⁺/p junction, which can work as an effective lifetime killer. The fully-silicided S/D structures with CoSi₂ prove to be a valid structure for the FD SOI CMOS devices in the sub-0.13 μm technology node.