Cost modeling of low-temperature large-area polysilicon thin film transistor liquid crystal display manufacturing

The potential to integrate the scan and data driver circuitry and thereby reduce the cost of active-matrix liquid-crystal displays (AM-LCDs) has been one of the major reasons for pursuing a low-temperature poly-Si thin-film transistor (TFT) technology. Improvements in low-temperature large-area processing technologies have made poly-Si TFT technology compatible with conventional amorphous-Si substrates. We examine the cost of manufacturing poly-Si TFT LCDs for 10-in. SVGA resolution color displays. We present a detailed cost analysis of manufacturing a low-temperature poly-Si TFT LCD with integrated drivers including the operating costs of manufacturing. The cost per display for manufacturing plants running amorphous-Si and poly-Si TFT processes at their minimum efficient scale are compared. A cumulative Poisson yield model is presented which takes into account the additional area and process steps requirements for a poly-Si TFT process with integrated drivers. The overall poly-Si AM-LCD manufacturing cost is lower despite having a higher front-end TFT array manufacturing cost due to the additional complexity of fabricating CMOS drivers as well as the lower TFT yield. Our results indicate that low- temperature poly-Si AM-LCDs with integrated drivers will be cost competitive with a-Si AM-LCDs.