CHARACTERISTICS OF TOP-GATE THIN-FILM TRANSISTORS FABRICATED ON NITROGEN-IMPLANTED POLYSILICON FILMS

The electrical characteristics of top-gate thin-film transistors (TFT' s) fabricated on the nitrogen-implanted polysilicon of the doses rangi ng from 2 x 10(12)-2 x 10(14) ions/cm(2) were investigated in this wor k, The experimental results showed that nitrogen implanted into polysi licon followed by an 850 degrees C 1 h annealing step had some passiva tion effect and this effect was much enhanced by a following H-2-plasm a treatment. The threshold voltages, subthreshold swings, ON-OFF curre nt ratios, and field effect mobilities of both n-channel and p-channel TFT's were all improved, Moreover, the hot-carrier reliability was al so improved, A donor effect of the nitrogen in polysilicon was also fo und which affected the overall passivation effect on the p-channel TFT 's.