Clarification of Additional Mobility Components associated with TaC and TiN Metal Gates in scaled HfSiON MOSFETs down to sub-1.0nm EOT

To clarify mobility (mu) limiting factors in aggressively scaled metal gate (MG)/high-k insulator (HK) MOSFETs, additional mu components associated with TaC and TiN MGs and their physical origins are investigated. With a TaC/HfSiON stack, _{mu@Eeff=1M V/cm} of 215 cm²/Vs, 87% of Poly Si/SiO² universal, at EOT of 0.91nm is achieved. Two different types of additional scattering are, for the first time, identified; the one is remote Coulomb scattering (RCS) by the charges near the HK-IL interface, induced by diffused metals, and the other becomes obvious near sub-1.0 nm-EOT region, plausibly originating from defects near the MG-HK interface.