| 研究生: |
鍾明達 Chung, Ming-Ta |
|---|---|
| 論文名稱: |
非對稱與對稱型非晶矽薄膜電晶體元件之照光特性研究 Investigation on Light Illumination of Asymmetric and Symmetrical type a-Si TFT |
| 指導教授: |
張守進
Chang, Shoou-Jinn |
| 學位類別: |
碩士 Master |
| 系所名稱: |
電機資訊學院 - 電機工程學系碩士在職專班 Department of Electrical Engineering (on the job class) |
| 論文出版年: | 2010 |
| 畢業學年度: | 98 |
| 語文別: | 中文 |
| 論文頁數: | 101 |
| 中文關鍵詞: | 非晶矽 、薄膜電晶體 |
| 外文關鍵詞: | a-Si, TFT |
| 相關次數: | 點閱:85 下載:10 |
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在a-Si:H TFT元件中,主要有兩大漏電流途徑:其一為由半導體層中a-Si中之缺陷所引起之漏電流,另一為半導體層a-Si因光照射所產生之漏電流。
由a-Si中之缺陷所引發之漏電流,從製程方面之改善方式,一般採用氫化製程以及其他製程參數調整,達到成長低缺陷密度的a-Si:H薄膜,來降低其漏電流。因a-Si受光照射所產生之漏電流,從設計面之改善方式,以 ”Botton gate” 製程為例,一般採用 ”Island-In” (利用Gate 金屬層來屏蔽來自於背光之照射光對a-Si影響之設計,) 方式來降低光漏流對畫面顯示之影響,但此設計方式,於a-Si:H TFT的源極/汲極與半導體層之邊緣,因為無N+層阻擋電洞,而產生新的漏流途徑。
於實際應用中,在TFT之像素設計多為逆交錯型結構下(Bottom Gate形式),由於閘極金屬層厚度影響(~3000 Å),無法完全阻隔來自於面板下方背光模組所產生之光照射現象對半導體層之影響,即使TFT元件設計為”Island-In”架構,由實驗數據中,仍可觀察出其照光前後之差異性。
本論文主要探討在TFT之像素設計為逆交錯型結構下,搭配後通道蝕刻製程(BCE,Back-Channel Etch),對稱型TFT元件與非對稱型TFT元件之照光特性探討。在不同的通道長度與通道寬度下,其包含遷移率、臨界電壓,Ion、Ioff之變化。
There are two main ways of leakage current on the a-Si:H TFT device: one is from the defect of a-Si, the other is caused by light effect of a-Si.
The leakage current caused by the defect of a-Si, in most cases of improvement mothod of process, they adopt hydrogenation process and others process parameter tuning to gain the lower defect density film of a-Si:H to reduce the leakage current.
The leakage current caused by the light effect of a-Si, in most cases of improvement mothod of design, they adopt “Island-in”(use metal layer as mask to shield a-Si:H from the light of back-light) method to lower the display impact of leakage current caused by light effect, but in the case of this design, it will develop the new leakage route due to there is without N+ layer to trap electric hole in the edge of source/drain and semiconductor layer.
For the realistic application, the TFT pixel design is inverted staggered structure(Bottom Gate form), it couldn’t fully stop the impact of the light emission from the back-light unit to the semiconductor layer. Although the design of TFT device is “Island-in” structure, from the experiment data, we could still observe the difference between w/ light emission and w/o light emission.
The paper mainly discuss light feature of symmetric and asymmetric TFT device with back-channel etch process(BCE) on the TFT pixel design of inverted staggered structure. On the different channel length and width, the change of electron mobility, threshold voltage, Ion, and Ioff.
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