CHARACTERISTICS OF THIN-FILM TRANSISTORS FABRICATED IN POLYSILICON FILMS DEPOSITED BY PLASMA ENHANCED CHEMICAL VAPOR-DEPOSITION

Thin-film transistors (TFTs) fabricated in polysilicon films deposited by plasma enhanced chemical vapor deposition (PECVD) were characterized. The transistors were fabricated using a low temperature process (i.e., less-than-or-equal-to 700-degrees-C). The characteristics of the devices were found to improve as the deposition temperature of the polysilicon film increased. The best characteristics (mu-FE of 15 cm2/Vs and V(TH) of 2.2 V) were measured in the devices fabricated in the film deposited at 700-degrees-C. The devices fabricated in the PECD polysilicon films were compared to those fabricated in polysilicon films deposited by thermal CVD in the same reactor in order to decouple the effect of the plasma. A coplanar electrode structure TFT with adequate characteristics (mu-FE of 8 cm2/Vs) was also demonstrated in the PECVD polysilicon films.