Yong-Hwan Park

16.2: World-Best Performance LTPS TFTs with Robust Bending Properties on AMOLED Displays

This study reported a low temperature polycrystalline silicon LTPS thin film transistor TFT fabrication process on plastic substrates for flexible display applications. Polycrystalline silicon poly-Si films were formed by excimer laser annealing ELA method. It was found by ELA thermal simulation that there was around 70 □ on plastic surface during ELA crystallization process. The excimer laser irradiated film was analyzed by using various spectroscopic methods such as X-ray diffraction, scanning electron microscopy, and atomic force microscopy. Dehydrogenation and activation processes were performed by a conventional LTPS method without causing any plastic substrate distortion. The fabricated poly-Si TFT on a flexible backplane shows a very good performance with field effect mobility of 95.3 cm2/Vs, on/off ratio current ratio > 108, and threshold voltage of −1.6 V. Bending tests after a delamination process were also performed with TFT backplane samples.