High-performance poly-Si TFT with ultra-thin channel film and gate oxide for low-power application

In this paper, an ultra-thin-body thin-film transistor (UTB-TFT) with a raised source/drain structure is demonstrated and compared with a conventional thin-film transistor. A significant suppression of leakage current and an improvement in subthreshold swing (SS) resulting from the reduced body thickness is observed. The minimum current can be decreased from 245 pA to 42 pA as the channel film thickness is scaled down from 60 nm to 10 nm. However, an ultra-thin-channel film constrains the average grain size and severely impacts the saturation current. Fortunately, by decreasing the gate oxide thickness from 20 nm to 10 nm, the saturation current of a UTB-TFT can be significantly increased from 13 μA to 25 μA. Experimental results suggest that UTB-TFTs with a sub-10 nm gate oxide display great promise for future low-power, high-performance three-dimensional integrated circuits.