Covalent Nature in La-Silicate Gate Dielectrics for Oxygen Vacancy Removal

This letter focuses on studying the characteristic behavior of oxygen in La-silicate dielectrics by comparison with
$\hbox{HfO}_{2}$
dielectrics.
${V}_{\rm FB}$
shift of La-silicate caused by oxygen annealing is found to be stable even after reduction annealing unlike with
$\hbox{HfO}_{2}$
. Moreover, reduced gate leakage current and improved effective mobility of nMOSFETs with La-silicate are observed by oxygen incorporation, suggesting the annihilation of oxygen vacancy. Since the oxygen in La-silicate covalently exists adjacent to the Si atom, stability of oxygen in La-silicate can be understood in terms of strong bonding of covalent nature.