Effect of nitrogen profile on tunnel oxynitride degradation with charge injection polarity

The relationship between nitrogen profiles and polarity dependence of wearout and breakdown in oxynitride films was investigated. With positive bias stress, higher concentration of nitrogen atoms near an oxynitride/Si interface (similar to 2 at.%) and in the oxynitride bulk (similar to 0.3 at.%) reduce charge trap and interface state generation, and produce greater charge-to-breakdown (Q(bd)) In contrast, with negative bias stress, nitrogen atoms near an interface decrease the number of charge traps, but, cannot reduce interface state generation, and thus give smaller Q(bd). Furthermore, nitrogen atoms near an oxynitride surface (over 1.5 at.%) cause undesirable results for both bias stresses. Optimum nitrogen profile in an oxynitride film is discussed the viewpoint of reliability for both bias stresses.