Characterization of interface defects related to negative-bias temperature instability in ultrathin plasma-nitrided SiON/Si〈1 0 0〉 systems

Interface defects related to negative-bias temperature instability (NBTI) in an ultrathin plasma-nitrided SiON/Si〈1 0 0〉 system were characterized by using conductance-frequency measurements, electron-spin resonance measurements, and synchrotron radiation X-ray photoelectron spectroscopy. It was confirmed that NBTI is reduced by using D2-annealing instead of the usual H2-annealing. Interfacial Si dangling bonds (Pb1 and Pb0 centers) were detected in a sample subjected to negative-bias temperature stress (NBTS). Although we suggest that NBTS also generates non-Pb defects, it does not seem to generate nitrogen dangling bonds. These results show that NBTI of the plasma-nitrided SiON/Si system is predominantly due to Pb depassivation. Plasma nitridation was also found to increase the Pb1/Pb0 density ratio, modify the Pb1 defect structure, and increase the latent interface trap density by generating Si suboxides at the interface. These changes are likely to be the causes of NBTI in ultrathin plasma-nitrided SiON/Si systems.