Impact of channel engineering on unity gain frequency and noise-figure in 90nm NMOS transistor for RF applications

In this paper, we have studied and compared the RF performance metrics, unity gain frequency (f_t) and noise figure (NF), of the devices with channel engineering consisting of halo and super steep retrograde channel (SSRC) implants, and the devices with uniform channel doping concentration, using process, device, and mixed mode simulations. The simulation results show that at 90nm gate lengths, for a given off-state leakage constraint (I_OFF), devices with uniform channel doping concentration deliver higher f_t and lower NF than the devices which used halo and SSRC, due to better sub-threshold slope and transconductance. However, at 0.25 μm technology the same is not true. Therefore, in the 90 nm devices uniform channel doping profile is recommended to get better RF performance.