針對系統面板應用之低溫多晶矽薄膜電晶體之設計與特性分析

Design and Analysis of LTPS TFTs for SOP Applications

李淂裕(Te-Yu Lee)

指導教授 ： 金雅琴 ； 林崇榮

國立清華大學/電機資訊學院/電子工程研究所/博士(2013年)

https://doi.org/10.6843/NTHU.2013.00057

摘要

低溫多晶矽薄膜電晶體可謂當今最重要的移動裝置顯示技術；由於優越的元件特性，主動矩陣低溫多晶矽薄膜電晶體顯示器提供高亮度、高效率、廣視角和高對比度；加上支援動態影像所需的快速響應、超薄模組、低功耗與低製造成本的優勢，更進一步滿足可攜式電子產品的需求。
然而，應用在行動設備上，低溫多晶矽薄膜電晶體技術仍然面臨著許多挑戰才能臻至理想，例如高解析度面板，系統面板與具可撓式之面板技術。
在本篇論文中，透過對低溫多晶矽薄膜電晶體的研究，更可以確定其在移動裝置應用之優勢。在高解析度液晶顯示器應用上，低溫多晶矽薄膜電晶體漏電流可經由多晶矽晶粒結構突起引發的區域性正電荷注入獲得壓抑。在高強度背光源的面板應用上，採用非對稱遮蔽閘與環狀遮蔽閘的低溫多晶矽薄膜電晶體除了有效降低光漏電流，更能降低浮動遮蔽閘引起的汲極導通。在系統面板的應用上，成功地使用傳統低溫多晶矽薄膜電晶體製程實現了超過三個數量級的讀取電流差且具有快速寫入與高抗讀取干擾特性的金屬-氮化物-氧化物-矽（MNOS）一次編程唯讀記憶體（OTP）及可靠的資料儲存能力。在高解析度有機發光二極體面板的應用上，發展出有效率的嵌入式畫素電流提升技術並且成功地改善2.4吋2T1C有機發光二極體面板的亮度不均性，其亮度不均的改善可由8.1%降至4.9%。此技術除了有效地改善亮度不均性亦可避免複雜的畫素補償電路和外加記憶體，製程上更具備與現有低溫多晶矽薄膜電晶體製程完全相容的低成本優勢。

關鍵字

低溫多晶矽薄膜電晶體 ； 金屬-氮化物-氧化物-矽 ； 一次編程唯讀記憶體 ； 有機發光二極體 ； 系統面板

並列摘要

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.

並列關鍵字

LTPS TFT ； MNOS ； OTP ； OLED ； SOP

參考文獻

[2] T. P. Brody, "When — If ever — Will the CRT be replaced by a flat display panel?," Microelectronics Journal, vol. 11, pp. 5-9, 5// 1980.

[3] M. Catelani, L. Ciani, L. Signorini, and G. Barile, "TFT-LCD for avionics applications: development, characterization and reliability analysis," in Instrumentation and Measurement Technology Conference (I2MTC), 2010 IEEE, 2010, pp. 647-651.

[4] Y. Ishii, "The World of Liquid-Crystal Display TVs - Past, Present, and Future," Display Technology, Journal of, vol. 3, pp. 351-360, 2007.

[5] D. E. Mentley, "State of flat-panel display technology and future trends," Proceedings of the IEEE, vol. 90, pp. 453-459, 2002.

[6] Y.-M. Tsai, D.-Z. Peng, C.-W. Lin, C.-H. Tseng, S.-C. Chang, P.-Y. Lu, et al., "40.2: Invited Paper: LTPS and AMOLED Technologies for Mobile Displays," in SID Symposium Digest of Technical Papers, 2006, pp. 1451-1454.