Mixed-signal and noise properties of nMOSFETs with HfSiON/TaN Gate Stacks

Digital- and analog properties of nMOSFETs with HfSiON/TaN gate stacks are discussed. I/sub on//I/sub off/, analog gain A/sub v/, and 1/f noise as function of the Hf-content in the gate dielectric were determined. It is observed that digital specs can be met if correct metal workfunctions are used. It is further found that 1/f noise is independent of the Hf-content in the gate stack. This result suggests that the dielectric/metal gate interface should receive major attention for reducing 1/f noise in nMOSFETs with high-k/metal gate stacks. This is in particular true in view of the observed low A/sub v/ values and the knowledge that pocket engineering - not applied in this experiment - will further degrade both noise and analog gain.