Mobility measurement and degradation mechanisms of MOSFETs made with ultrathin high-k dielectrics

Accurate measurements and degradation mechanisms of the channel mobility for MOSFETs with HfO₂ as the gate dielectric have been systematically studied in this paper. The error in mobility extraction caused by a high density of interface traps for a MOSFET with high-k gate dielectric has been analyzed, and a new method to correct this error has been proposed. Other sources of error in mobility extraction, including channel resistance, gate leakage current, and contact resistance for a MOSFET with ultrathin high-k dielectric have also been investigated and reported in this paper. Based on the accurately measured channel mobility, we have analyzed the degradation mechanisms of channel mobility for a MOSFET with HfO₂ as the gate dielectric. The mobility degradation due to Coulomb scattering arising from interface trapped charges, and that due to remote soft optical phonon scattering are discussed.