Excellent charge-trapping properties of ultrathin reoxidized nitrided oxides prepared by rapid thermal processing

7.7-nm-thick oxide nitrided at 950 degrees C and 1150 degrees C for 60 s were reoxidized by rapid thermal processing in dry oxygen at 900-1150 degrees C for 15-200 s. The nitridation-condition and reoxidation-condition dependences of charge to breakdown (Q/sub BD/), flat-band voltage shift ( Delta V/sub FB/), and increase of midgap interface state density Delta D/sub itm/ under high-field stress were studied. Rapid reoxidation achieves striking improvement of dielectric integrity: the Q/sub BD/ is improved by about 16 times and both the Delta V/sub FB/ and Delta D/sub itm/ are reduced by more than two orders of magnitude compared with those of thermal oxides. A correlation between the improvement and a reduction of hydrogen concentration by reoxidation is found.<
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