Experimental determination of mobility scattering mechanisms in Si/HfO/sub 2//TiN and SiGe:C/HfO/sub 2//TiN surface channel n- and p-MOSFETs

We demonstrate by an extensive experimental study of HfO/sub 2//TiN and SiO/sub 2//TiN gate stacked-transistors compared with the SiO/sub 2//poly-Si reference, that the hole mobility is mainly degraded by the surface roughness (SR) linked to the presence of TiN. We thus propose high mobility SiGe or SiGe:C surface channel pMOSFETs with HfO/sub 2//TiN gate stacks using an adequate valence band engineering near the dielectric/channel interface (up to 100% hole mobility enhancement at E/sub eff/ = 1 MV/cm). On the other hand, the electron mobility with HfO/sub 2//TiN gate stacks is reduced by remote Coulomb scattering (RCS).