A two-step annealing process for Ni silicide formation in an ultra-thin body RF SOI MOSFET

A two-step annealing process for Ni silicide formation in an ultra-thin body (UTB) RF SOI MOSFET is proposed to prevent a dramatic increase of the gate leakage current from the in-diffusion of Ni into the channel. The first step of the annealing process was performed at a low temperature for di-nickel silicide (Ni2Si) formation, resulting in no in-diffusion of Ni into the channel. Next, the second step of the annealing process was performed at 500 °C for the formation of mono-nickel silicide (NiSi). Finally, the optimized Ni silicide SD with low resistance (5 Ω/□) and a low leakage current was achieved on the UTB. Using the proposed two-step silicide process, UTB RF MOSFET with a gate length of 50 nm a 20-nm UTB was successfully fabricated and showed the good RF properties with a cut-off frequency of 138 GHz.