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

The physics and effects of nitrogen incorporation into HfO2 films were studied in detail. The authors found that only a trace amount (∼5%) of nitrogen can be introduced into the HfO2 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 (VO) and replacement of VO 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 HfO2∕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.