由於氧化物半導體擁有許多有助於未來顯示器發展的優點，故近年來吸引了相當多的注目。然而氧化物半導體要實際應用於顯示器工業仍有許多可靠度與穩定性問題待需解決，例如於閘極電應力、照光、以及環境氣氛下元件產生的不穩定性。
本研究探討於閘極偏壓電應力下元件的可靠度。非晶態氧化銦鎵鋅(amorphous InGaZnO, a-IGZO)薄膜電晶體(Thin-Film Transistor, TFT)於閘極正偏壓電應力下，由於通道電子會透過熱場發射(Thermionic-field emission)機制而被捕獲至閘極絕緣層或閘極絕緣層/IGZO介面，造成元件起始電壓的變大。然而，不同於以往文獻報導之銦鎵鋅氧薄膜電晶體於閘極負偏壓電應力操作下相當穩定之情況，元件於閘極負偏壓電應力下，表現出異常的導通電流劣化以及電流擁擠現象。研究發現，當未覆蓋保護層之銦鎵鋅氧薄膜電晶體暴露於環境氣氛下時，環境中之水氣會造成銦鎵鋅氧薄膜背表面之水解，當元件施加閘極負偏壓電應力時，氫離子會由ZnO-H鍵解離出來而造成電性上的不穩定性。本研究也透過ISE-電腦輔助設計模擬、霍氏轉換紅外光譜儀以及水氣氛壓調變量測來闡明此異常元件劣化的物理機制。
為了阻擋環境氣氛對a-IGZO TFTs主動層之影響，故必須引入適當的保護層以隔絕環境中的氣氛與主動層接觸。過往文獻指出，由於氧化鋁緻密的結構使其成為良好的保護層，但氧化鋁的沉積速率過於緩慢。為了提高產率，我們使用矽鋁氮氧材料來取代氧化鋁作為銦鎵鋅氧薄膜電晶體的保護層。由實驗結果發現矽鋁氮氧擁有與氧化鋁相當的阻擋環境氣氛之效果，且沉積速率約為氧化鋁的125倍，可以大幅提高產率。因此，為了阻擋環境氣氛對a-IGZO薄膜電晶體造成的電性不穩定與劣化，我們採用矽鋁氮氧材料作為保護層。由於矽鋁氮氧保護層阻擋了外界的氣氛，因此大幅提升元件於閘極偏壓電應力下的穩定性。

Thin film transistors (TFTs) based on amorphous InGaZn oxide (a-IGZO) have been studied extensively for potential application in next-generation flat-panel displays. Although a-IGZO TFTs exhibit superior optical and electrical properties, their long-term stability and reliability under bias, illumination stresses and/or the surrounding ambience is a critical issue that has attracted considerable attention.
In this study, we investigate the impact of the stability of indium–gallium–zinc oxide thin film transistors under gate-bias stress. The instability of threshold voltage shift under positive gate-bias stress was attributed to electron trapping in the gate dielectric and/or at the channel/dielectric interface through thermionic-field emission process. In addition, we also investigate the electrical degradation behaviors and mechanisms under negative gate bias stress. An anomalous on-current degradation and current crowding phenomenon can be observed after NGBS.
When the negative gate bias is applied on the TFT, hydrogen ions will dissociate from ZnO-H bonds and the dissociated hydrogen ions will cause electrical instability under NGBS. The capacitance-voltage measurement, ISE-Technology Computer Aided Design (ISE-TCAD) simulation tool, Fourier Transform Infrared Spectroscopy, and moisture partial pressure modulation measurement is are utilized to confirm the degradation mechanism.
Oxygen and moisture was identified as a critical factor inducing the threshold voltage instability. Accordingly, adopting a passivation layer to protect the active layer of the a-IGZO TFTs is essential. This study reports the use high sputter rate SiAlNO layer (approximately 125 times higher than Al2O3) to passivate the a-IGZO channel of a bottom-gate TFT. Experimental results demonstrate that a SiAlNO passivation layer can effectively improve the stability of a-IGZO TFTs tested under both PGBS and NBIS conditions.

誌謝 ii
中文摘要 iii
Abstract v
目錄 vii
圖片目錄 ix
表格目錄 xiii
第一章.序論 1
1-1研究背景 1
1-2主動層材料性質與優劣比較 2
第二章.元件特性與電性量測 9
2-1元件結構 9
2-2 元件基本特性 10
2-2-1 輸出特性曲線 10
2-2-2 電容-電壓轉換特性 10
2-3參數萃取 12
2-3-1電流與載子遷移率 13
2-3-2臨界電壓(Threshold Voltage : VTH) 14
2-3-3次臨界擺幅 (Subthreshold swing, S.S.) 14
2-4儀器介紹 16
2-4-1電性量測設備 16
2-4-2製程設備 16
2-4-3材料分析設備 17

第三章.研究動機與目的 25
3-1 金屬氧化物電晶體的不穩定性 25
3-1-1閘極電應力下的不穩定現象 25
3-1-2環境氣氛的不穩定現象 26
3-1-3照光產生不穩定現象 27
3-2實驗目的 27
第四章. a-IGZO TFT於閘極電應力之不穩定性 31
4-1簡介 31
4-2實驗架構 32
4-3結果與討論 32
4-3-1閘極正偏壓電應力之載子捕獲效應 32
4-3-2負偏壓閘極電應力之表面水解效應 36
第五章.矽鋁-based材料保護層應用於a-IGZO TFT 53
5.1 簡介 53
5-2 實驗架構 54
5-3-1 SiAlNO保護層退火前後差異 56
5-3-2 SiAlNO保護層增強元件穩定度 58
第六章.結論 70
Reference 72

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