Planarized copper gate hydrogenated amorphous-silicon thin-film transistors for AM-LCDs

We report the first fabrication of inverted-staggered back-channel-etch hydrogenated amorphous-silicon (a-Si:H) thin-film transistors (TFTs) with a planarized Cu gate electrode. The Cu gate-planarized (GP) a-Si:H TFTs, incorporating benzocyclobutene and a-SiN/sub x/:H as a double-layer gate insulator, had a field-effect mobility of 0.75 cm/sup 2//V-s, a threshold voltage of 4.92 V, and a subthreshold swing (S) of 0.48 V/dec. These results demonstrate that the GP-TFTs can have an electrical performance comparable with the conventional TFTs without gate planarization. Thus, the gate planarization technology is suitable for application in large-area and high-resolution active-matrix liquid-crystal displays.