TCAD-based investigation of 1/f noise in advanced 22 nm FDSOI MOSFETs

In this work, the mechanistic insights behind low-frequency noise (LFN) of the advanced ultrathin body and buried oxide fully depleted silicon-on-insulator based metal–oxide–semiconductor field effect transistor (MOSFET) are unveiled. The gate voltage-induced noise power spectral density (S_VG) is inversely proportional to frequency f (i.e., S_VG $∝1/fγ$⁠, $γ∼$ 1 is the frequency exponent) for nMOSFET and pMOSFET. Detailed numerical simulations are performed and well calibrated to reported S_VG vs f characteristics. Simulation results are consistent with the reported experimental observations. We demonstrate that LFN is caused by the charge carrier number fluctuation mechanism, which is originated by trapping and de-trapping of channel charge carriers via. bulk traps (from oxygen vacancies) in the hafnium dioxide (HfO₂) layer, but not through traps at the silicon dioxide (SiO₂)/channel interface. This work therefore explains the similar magnitude of S_VG in both nMOSFET and pMOSFET observed experimentally and further suggests that oxygen vacancies inside gate oxides are critical to suppress the low-frequency noise in emerging high-k based MOSFETs.