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

Abstract

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 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.