Study of influence of nitrogen concentration in nitrided oxide on interface trap generation

In this study, a novel technique, i.e. the direct-current current-voltage (DCIV) method is used to quantitatively examine the influence of nitrogen concentration in nitrided oxide on interface trap generation caused by DC and dynamic Fowler-Nordheim (FN) injections. For both DC and dynamic FN stresses, a power-law stress-time dependence of interface trap generation is always observed, and the increase of nitrogen concentration leads to a significant suppression of interface trap generation. For the dynamic stress, interface trap generation increases with frequency, but the interface trap generation at each frequency is reduced with a higher nitrogen concentration. A comparison of interface trap generation between DC and dynamic stresses and explanation for the difference are presented. The nitridation effect on the interface trap generation can be explained by the models based on either the rigid Si-N bonds at the interface or the nitrided oxide impediment to the damaging positive species such as H⁺ or holes.