A systematic study of the initial electrical and radiation hardness properties of reoxidized nitrided oxides by rapid thermal processing

The initial electrical and radiation hardness properties of MOS capacitors with reoxidized nitrided oxides (RNO) structures are systematically investigated by changing the pressure, temperature, and times of nitridation and reoxidation in rapid thermal processes. It was found that the initial flat-band voltage (V_fb) and midgap interface trap density (D_itm) are strongly dependent on the growth conditions and show concave or convex “turnaround” dependency on some process parameters. This may be explained by the hydrogen evaporation and oxygen passivation mechanisms. The radiation induced flat-band voltage shift (ΔV_fb) and midgap interface trap density shift (ΔD_itm) are also growth-condition dependent and show different “turnaround” dependencies on some process parameters from those observed in initial properties. This may be explained by the variations of the amount of hydrogen-related species such as Si-NH, Si-H, or Si-OH, and nitrogen-related species, such as Si-N, in the oxide bulk and at the Si/SiO₂ interface. Finally, the sample with a reoxidation pressure of 250 torr, a reoxidation temperature of 1050°C, and a reoxidation time of 100 s is suggested to be the most radiation-hard together with good initial properties for RNO devices