Intrinsic Origin of Electron Mobility Reduction in High-k MOSFETs - From Remote Phonon to Bottom Interface Dipole Scattering

We show that the mobility degradation at low fields is predominantly due to a dipole layer intrinsically formed at the HfO
2
/SiO
2
interface. This dipole layer is also responsible for the anomalous V
FB
(V
TH
) shift in high-k MOSFETs. Contribution of remote phonon scattering to the mobility degradation is very little, as revealed by comparing the mobility behaviors for MOSFETs with different crystal symmetry of HfO
2
dielectrics.