Characterization of interface defects related to negative-bias temperature instability in ultrathin plasma-nitrided SiON/Si⟨100⟩ systems

Interface defects related to negative-bias temperature instability (NBTI) in an ultrathin plasma-nitrided SiON/Si<100> 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 D-2-annealing instead of the usual H-2-annealing. Interfacial Si dangling bonds (P-b1 and P-b0 centers) were detected in a sample subjected to negative-bias temperature stress (NBTS). Although we suggest that NBTS also generates non-P-b 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 P-b depassivation. Plasma nitridation was also found to increase the P-b1/P-b0 density ratio, modify the P-b1 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. (C) 2004 Elsevier Ltd. All rights reserved.