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We present detailed device results from polysilicon TFT's fabricated at a maximum processing temperature of /spl les/100/spl deg/C on flexible plastic polyethylene terephthalate (PET) substrates. These substrates are low cost, flexible, rugged, and optically transparent which makes them suitable for transmissive AMLCD applications. Our TFT process uses 4 mask levels to define a self-aligned aluminum top-gate structure. Adding pixel capacitors requires two more mask levels. We use a /spl lambda/=308 nm XeCl excimer laser to both crystallize the as-deposited PECVD a-Si:H and to heavily dope the source-drain regions. An in situ IR laser probe allows monitoring and controlling of the Si melt depth. By varying the laser processing parameters of energy fluence and number of pulses at each location, we have succeeded in fabricating TFT's with I/sub on/I/sub off/ ratios of >10/sup 6/ and electron mobilities >5 cm/sup 2//V-s without substrate damage.