Modeling of nitrogen profile effects on direct tunneling probability in ultrathin nitrided oxides

The dependence of the gate tunneling current (Jg) on nitrogen profile (N profile) within an ultrathin silicon oxynitride film is reported. It was found that gate tunneling current is dependent on N profile, even with equal oxide thickness and nitrogen dosage. Gate tunneling current increased with steeper N profile, and it had higher sensitivity for p-type metal-oxide-semiconductor field-effect transistor (MOSFET) than n-type MOSFET. A direct tunneling model based on Wentzel-Kramers-Brillouin approximation has been proposed. The model described the influence of N profiles on gate tunneling current through local change of dielectric constant, band bending, and effective mass. Also, it reasonably explained the different Jg sensitivity in n-∕p-MOSFETs, a phenomenon that has not been addressed in earlier publications.