Novel Vacuum Encapsulation Applied for Improving Short-Channel Immunity on Poly-Si Thin Film Transistors

Abstract

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 only with a simple process. The T-Gate structure is formed only by a selective undercut-etching technology of the Mo/Al bilayers. 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 effect and to improve the breakdown characteristics. It is attributed to the undoped offset region and vacuum gap to reduce the maximum electric field at drain junction.