Low temperature poly-Si active matrix LCDs

Summary form only given, as follows. At the present time the majority of active matrix liquid crystal displays are fabricated with a-Si:H bred thin film transistors (TFTs) or diodes (TFDs) as the pixel switching element. Poly-Si TFT technologies offer the advantage of a high carrier mobility (μ>100 cm² V^-1 S^-1) compared with a-Si:H (μ<1 cm² V^-1 S^-1), which means it becomes feasible to integrate poly-Si row and column drive circuits onto the same glass plate as the active matrix array, This is particularly desirable in small displays for reasons of compactness and cost. The most advanced poly-Si technology is a high temperature process on quartz substrates which is currently being used to make small high resolution displays with integrated drivers, such as high resolution LCD projectors and viewfinders. It is believed that the realisation of a low temperature poly-Si technology will greatly extend the range of poly-Si based AMLCDs. This is because low temperature poly-Si TFTs can be used to fabricate displays with integrated row and column drive circuits on large glass substrates, thus bridging the gap between high temperature poly-Si on quartz and a-Si:H processes on glass. This talk will first review the advantages and discuss the present status of poly-Si AMLCDs. Finally, some of the major issues associated with the fabrication of low temperature poly-Si TFTs will be addressed, including: (i) deposition and crystallisation of the poly Si film, (ii) controlling leakage current in the TFTs and (iii) TFT stability