Effects of silicides and device structure on the characteristics and circuit performance of poly-silicon thin film transistors for active-matrix liquid-crystal displays

The leading technology in flat panel displays is active matrix addressed displays, with either amorphous or polycrystalline silicon thin film transistors as the pixel switching element. For cost and performance reasons, integration of display driver circuitry onto the display substrate is desirable.; This thesis focuses on devices for driver circuitry necessary for AMLCD operation. Circuits to control the data transferred to the pixels are discussed, and their timing constraints determined. The ability of amorphous and polysilicon Thin Film Transistors (TFTs) to meet the needs of the circuits is considered. The characteristics of the devices are examined to determine their utility in driver circuit design.; One of the major limitations of thin film transistors is their series resistance, which decreases the output current and slows the circuit response. In this work, self-aligned silicidation has been developed for thin film transistors to reduce the extrinsic resistance. The principles of silicidation are reviewed, and applied towards the development of cobalt and nickel silicide processes on thin polycrystalline and amorphous silicon and silicon-germanium films. The effect of the film on the electrical properties of silicide is studied.; Cobalt and nickel silicides are used on the source and drain of polysilicon TFTs, and their effects on the device characteristics are analyzed. Their impact is greatest on ultra-thin film polysilicon devices, where the high series resistance limits the current to about 1{dollar}mu{dollar}A. With silicides, the output current is increased one-hundredfold. The improvement in AMLCD driver circuit performance by the incorporation of silicides is shown by circuit simulation.; The objective of this dissertation is to develop a silicidation process for polysilicon thin film transistors and determine the effects of this process on device performance, and project the improvements to AMLCD driver circuitry this process may provide.