| Summary: | 博士 === 國立清華大學 === 電子工程研究所 === 102 === Currently, LTPS TFTs are the most important display technology of mobile devices. Owing to the superior device characteristics, active-matrix driven LTPS TFT displays offer high brightness, high efficiency, wide viewing angle and high contrast ratio. Fast response time for moving images, ultra-thin module, low-power consumption, and low fabrication cost further fulfill the needs of portable electronics.
However, LTPS TFT technology still faces many challenges in realizing the ideal display in mobile applications such as high resolution, integrated circuitry and flexible display.
In this dissertation, reliability challenges of LTPS TFT technology for state-of-art mobile applications are investigated. For the high resolution liquid crystal displays, the average off-state leakage current of LTPS TFTs can be effectively suppressed by grain protrusion assisted localized FN operation. Under the increasing backlight system, asymmetric shielding gates as well as surround gate structure are proven to alleviate the drain turn-on effect caused by these floating bottom gates. For SOP applications, fully LTPS panel process compatible MNOS OTP cell with three-order read current difference, fast program efficiency, good data retention characteristics and high disturb immunity is demonstrated. For the high resolution AMOLED displays, efficient blanket boosting scheme is successfully applied to a 2.4-inch 2T1C AMOLED panel with illumination non-uniformity improving from 8.1% to 4.9%. This highly efficient trimming method can achieve uniform drive current without any additional compensation circuitry or external memory and fully compatible to current LTPS backplane for AMOLED display.
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