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

Abstract

We show that the mobility degradation at low fields is predominantly due to a dipole layer intrinsically formed at the HfO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> /SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> interface. This dipole layer is also responsible for the anomalous V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FB</inf> (V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</inf> ) 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 <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> dielectrics.