Electron spin resonance ofPbcenters is used to probe the dielectric/silicon interface in NH3‐nitrided oxide (NO) and reoxidized nitrided oxide (RNO) dielectrics. ThePbspectra observed in the NO and RNO systems differ from Si/SiO2systems only in the value ofg⊥; the &Dgr;g⊥suggests that the average value of the local strainatthedefectsitedecreases upon nitridation, and is little changed by subsequent reoxidation. The relaxation of thePbcenter structure appears to coincide with a reduction of compressive stress in the dielectric and an increase of tensile stress in the silicon substrate. These results suggest that differences in atomic scale strain due to nitrogen incorporation may be involved in the reduced radiation‐ and hot carrier‐induced interface state generation that NO and RNO dielectrics exhibit.