Threshold Voltage Swing Caused by Intense Phonon-Electron Interaction in High-k Dielectrics

The dynamic charge trapping/releasing behavior of oxygen vacancies (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</inf>) in the high-k dielectric layer of advanced multi-gate devices is investigated through a combination of first-principles calculations, non-radiative multi-phonon (NMP) model and TCAD simulations. Under the effect of phonon-electron interactions, the extremely large electron captures cross-sections (ECCS) for V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</inf> defects illustrates easy trapping/releasing of electrons, resulting in uncontrollable charge quantity in the dielectric layer and significant leakage current. Consequently, significant V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> swing of the operated device can be expected due to the electron capture and emission, thus degrading the reliability. These findings elucidate the fundamental mechanisms behind reliability degradation in scaled devices and establish a defect optimization foundation to optimize fabrication processes in future technology nodes.