A novel self-aligned field induced drain polycrystalline silicon thin film transistor fabricated by using a selective side etch process

Abstract

A novel T-shaped-gated (T-Gate) polycrystalline silicon thin-film transistor (poly-Si TFT) with 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 bi-layers. Then, vacuum gaps are in-situ embedded in this T-Gate structure subsequent to capping the SiH4-based passivation oxide under the vacuum process chamber. Experimental results reveal that the proposed T-Gate poly-Si TFTs have excellent electrical performance, which has maximum on-off current ratio of 4.6 x 10(7), and off-state leakage current at V-GS = -10 V and V-DS = 5V of about 100 times less than that of the conventional one. These improvements are attributed to the additional undoped offset region and the vacuum gap, which reduce the maximum electric field at drain junction while the sub-gate maintains the on-current. Therefore, such a T-Gate poly-Si TFT is very suitable for the applications and manufacturing in active matrix liquid crystal displays (AMLCDs) and active matrix organic light emitting diodes (AMOLEDs).