雙閘極氧化物半導體薄膜電晶體之研究

Studies of Oxide-Semiconductor-Based Double-Gate Thin Film Transistors

周玟坊(Wen-Fang Chou)

指導教授 ： 吳忠幟

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.03037

摘要

近年來，具有電子軌域(n-1) d^10 ns^0,(n≥4)之透明氧化半導體備受關注。氧化物薄膜電晶體可以在室溫製程，在非晶態下也能具有很高的載子遷移率。此外，因為通常具有寬能隙之故，所以在可見光區的波段是為透明，可提升平面顯示器之開口率或適用於透明電子元件。因上述所提到之優點，氧化物半導體具有高度取代氫化非晶矽和低溫多晶矽之潛力。
氧化物薄膜電晶體對背通道效應十分敏感，我們利用非晶態氧化銦鎵鋅的雙閘極薄膜電晶體(a-IGZO double-gate TFT)，以研究背通道效應。在本論文中，我們以探討a-IGZO 雙閘極薄膜電晶體的電性為主。首先，我們可利用閘極施加的偏壓和臨界電壓成線性的關係，可藉由改變閘極偏壓以調變臨界電壓。而上下閘極的偏壓同時施加時，從轉換特性圖可看到次臨界電壓斜率變大且載子遷移率也變高。
藉由偵測雙閘極薄膜電晶體的汲極電流改變，可作為觸控面板的感測器，若在觸控面板有足夠多的元件，就不僅可以分辨出其位置，還可以分辨出形狀，元件越多，解析度越高。透明的雙閘極薄膜電晶體在邏輯電路的實現上，也具有相當潛力。

關鍵字

氧化物薄膜電晶體 ； 非晶態氧化銦鎵鋅 ； 雙閘極薄膜電晶體 ； 背通道效應 ； 臨界電壓

並列摘要

Transparent oxide semiconductors with specific electronic configuration of (n-1) d^10 ns^0,(n≥4) have gained wide attention in recent years. Oxide thin-film transistors (TFTs) not only could be fabricated at room temperature, but also demonstrated to show high mobility in the amorphous phase. Moreover, they are transparent in visible region, which can improve the pixel aperture ratio in flat-panel displays or be used for transparent electronics. Because of these benefits mentioned above, oxide TFTs have high potential to replace hydrogenated amorphous silicon (a-Si:H) and low-temperature poly Si (LTPS) TFTs.
Oxide TFT is sensitive to the back channel effect. Therefore, we fabricated a-IGZO double-gate TFTs to study such effects. In this thesis, we studied the electrical characteristics of a-IGZO double-gate TFTs. First, we investigated the dependence of bottom-gate transfer characteristics on top-gate voltage. Threshold voltage of bottom-gate TFT could be linearly controlled by adjusting top-gate voltage without deteriorating other characteristics. Then, we showed that higher mobility and smaller subthreshold swing could be obtained when applying top-gate and bottom-gate voltage simultaneously.
Application of double-gate TFTs as touch sensors is feasible by detecting drain current variation when touching. It can detect the position and even the shape, if there are enough devices. Transparent double-gate TFTs are also promising on implementing logic circuits.

並列關鍵字

oxide TFTs ； a-IGZO ； double-gate TFT ； back channel effect ； threshold voltage

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