Polycrystalline silicon thin-film transistors (poly-Si TFTs) with self-aligned fluorine-doped SiO2 (FSG) spacer were investigated in this study. The presence of FSG spacers can effectively reduce the lateral electrical field near the drain side of a poly-Si TFT device, and strongly passivate Si dangling bonds at the grain boundaries. The significant enhancement in electrical performance suppresses serious kink effect and improves electrical reliability of poly-Si TFTs effectively. In addition, the proposed poly-TFT structure is uncomplicated and compatible with existing TFT manufacturing processes. (c) 2005 The Electrochemical Society.