Characterization on the current-voltage curves of ultrathin silicon dioxides incorporated with fluorine and/or nitrogen

Abstract

The current-voltage (I -V ) characteristics of ultrathin silicon dioxides incorporated with fluorine (F) and/or nitrogen (N) are investigated in this paper. A generalized trap-assisted tunnelling model is used to simulate the leakage current at electric fields of 4-10 MV cm −1 . This model can directly derive trap energy level ( t ) and trap concentration (N t ) values from simple I -V curves. From the simulation results, trap energy levels of fluorine and nitrogen are characterized to be 1.62-1.83 and 2.0-2.25 eV, respectively, while the trap concentrations range between 10 15 and 10 18 cm −3 for F or N impurities depending on the experimental conditions. With the introduction of nitrogen into SiOF films, t and N t values change significantly due to the formation of complex compounds of Si, O, F and N in silicon dioxides. Some possible explanations are given to clarify this mixing effect.