Effects and mechanisms of nitrogen incorporation into hafnium oxide by plasma immersion implantation

Abstract

The physics and effects of nitrogen incorporation into $\mathrm{Hf}{\mathrm{O}}_2$ films were studied in detail. The authors found that only a trace amount $(\sim 5\%)$ of nitrogen can be introduced into the $\mathrm{Hf}{\mathrm{O}}_2$ films using plasma immersion ion-implantation technique, regardless of implantation dose. They proposed that the nitrogen incorporation is due to the filling of O vacancies $\left(V_{\mathrm{O}}\right)$ and replacement of $V_{\mathrm{O}}$ O neighbors in the bulk with nitrogen atoms. At the interface, the nitrogen atoms exist in the form of Hf–N and Si–N bonding, which significantly improve the interface properties of the $\mathrm{Hf}{\mathrm{O}}_2∕\mathrm{Si}$ structure. Temperature-dependent capacitance-voltage characteristics measurements indicate that both interface and oxide trap densities were greatly reduced with the incorporation of trace amount of nitrogen atoms.