Electrical and physical properties of ultrathin reoxidized nitrided oxides prepared by rapid thermal processing

A systematic study of the correlations between electrical and physical properties of nanometer-range reoxidized nitrided oxide films is reported. Rapid thermal processing was applied to the full fabrication process 7.7-nm-thick oxides nitrided at various conditions were reoxidized at 900-1150°C for 15-600 s. Nitridation- and reoxidation-condition dependences of charge-trapping properties, i.e. the flat-band voltage shift and the increase of midgap interface state density induced by a high-field stress, were studied. The hydrogen concentration in the film and the nitrogen concentration near the Si-SiO ₂ interface were measured by secondary ion mass-spectroscopy and Auger electron spectroscopy respectively. It was shown that striking improvement of the charge-trapping properties by rapid reoxidation is achieved by the reducing of hydrogen concentration while keeping the nitrogen concentration near the interface unchanged