Improving electrical performance of the scaled low-temperature poly-si thin film transistors using vacuum encapsulation technique

A novel T-shaped-gated (T-Gate) polycrystalline silicon thin-film transistor (poly-Si TFT) with in-situ vacuum gaps has been proposed and fabricated with a simple process. The T-Gate structure is formed only by a selective undercut-etching technology of the Mo/Al bi-layers. Then, vacuum gaps are in-situ embedded in this T-Gate structure subsequent to capping the SiH ₄ -based passivation oxide under the vacuum process chamber. The proposed T-Gate poly-Si TFT has demonstrated to suppress the short-channel effects by simulated and measured characterization. It is attributed to the undoped offset region and vacuum gap to reduce the maximum electric field at drain junction.