Impact of Dummy Gate Removal and a Silicon Cap on the Low-Frequency Noise Performance of Germanium nFinFETs

The impact of different process options on the low-frequency noise (LFN) performance and reliability of Ge nFinFETs is investigated. The results show that the LFN is mainly determined by carrier number fluctuations, and the density of traps in the high-kappa dielectric can be reduced by an extended dry clean. In some small-size devices, the Lorentzian-type noise comes from GR centers in the oxide layer or dislocations in the Ge fins. Due to the Coulomb scattering by charged oxide traps, Ge nFinFETs with higher input-referred voltage noise at flat band voltage (S-vgfb) usually have a lower mobility. Since the charged traps in the oxide layer are one of the main responsible factors for the shift of the threshold voltage, the transistors with bigger S-vgfb show higher PBTI degradation, and S-vgfb can be considered as an early indicator for the reliability of Ge nFinFETs.