An electron spin resonance study of the effects of thermal nitridation and reoxidation on P_b centers at (111) Si/SiO₂ interfaces

Electron spin resonance of P_b centers is used to probe the dielectric/silicon interface in NH₃-nitrided oxide (NO) and reoxidized nitrided oxide (RNO) dielectrics. The P_b spectra observed in the NO and RNO systems differ from Si/SiO₂ systems only in the value of g_⊥; the Δg_⊥ suggests that the average value of the local strain at the defect site decreases upon nitridation, and is little changed by subsequent reoxidation. The relaxation of the P _b center 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.