Interface defects responsible for negative-bias temperature instability in plasma-nitrided SiON/Si(100) systems

Interface defects generated by negative-bias temperature stress (NBTS) in an ultrathin plasma-nitrided SiON/Si(100) system were characterized by using D-2 annealing, conductance-frequency measurements, and electron-spin resonance measurements. D-2 annealing was shown to lower negative-bias temperature instability (NBTI) than H-2 annealing. Interfacial Si dangling bonds (P-b1 and P-b0 centers), whose density is comparable to an increase in interface trap density, were detected in a NBTS-stressed sample. The NBTI of the plasma-nitrided SiON/Si system was thus shown to occur through P-b depassivation. Furthermore, the nitridation was shown to increase the P-b1/P-b0 density ratio and modify the P-b1 structure. Such a predominance and structural modification of Pb1 centers are presumed to increase NBTI by enhancing the P-b-H dissociation. Although we suggest that NBTS may also induce non-P-b defects, nitrogen dangling bonds do not seem to be included in them. (C) 2003 American Institute of Physics.