Role of Nitrogen Atoms in Reduction of Electron Charge Traps in Hf-Based High- $\kappa$ Dielectrics

Effects of nitrogen incorporation on suppression of electron charge traps in Hf-based high- $\kappa$ gate dielectrics have been studied by first-principles calculations, focusing on interactions between N atoms and electrons trapped at oxygen vacancies $(V_{\rm O}{\hskip0.2pt}\hbox{'s})$. Our total energy calculations revealed that the formation energy of a doubly occupied state of $V_{\rm O}$ is significantly increased in $\hbox{HfO}_{x} \hbox{N}_{y}$ compared to that in $\hbox{HfO}_{2}$ . This clearly indicates that the electron charge traps at $V_{\rm O}{ \hskip0.2pt}\hbox{'s}$ are considerably suppressed by N incorporation.