直流二極濺鍍銦鎵鋅氧化物薄膜電晶體技術開發研究

Abstract

本研究論文成功地發展出一套新式具有高載子移動率 (High mobility) 的銦鎵鋅氧化 (Indium-Gallium-Zinc-Oxide) 薄膜電晶體 (Indium-Gallium-Zinc-Oxide Thin Film Transistors)，可應用於主動式顯示面板 (Active Matrix Liquid Crystal Display) 技術及搭配有機發光二極體面板 (Organic Light Emitter Diode Panel) 作為驅動電路，以增大顯示電晶體元件的效能與顯示畫素開口率，並減緩光漏電 (Photo leakage current) 對元件造成這影響。亦可推廣應用至驅動電路，達成系統面板整合技術 (System On Panel) 的遠景。在研究中，我們利用工業技術研究院顯示中心之直流二極濺鍍機台 (DC Sputter)，使用300 × 540 mm銦鎵鋅氧化物 (Indium-Gallium-Zinc-Oxide) 的靶材 (Target)，改變不同的直流濺鍍功率與基板移動速率，於玻璃基板上形成最具均勻性之薄膜，並在濺鍍過程中，控制通入氧氣的流量，來形成具備半導體特性之銦鎵鋅氧化物薄膜，而於半導體層製程完成後藉由後續的退火處理，我們成功建立一個得以在室溫環境之下，均勻沈積銦鎵鋅氧化物薄膜的沈積條件且具有最佳薄膜電晶體電性表現的半導體層 (Semiconductor layer)。在本論文中，我們也利用各種材料分析技術與儀器，如原子力顯微鏡 (AFM)、X光薄膜繞射儀 (XRD)、掃瞄式電子顯微鏡 (SEM)、四點探針 (Four-Point Probe) 等...來針對銦鎵鋅氧化薄膜之結晶性 (Crystallization)、晶格尺寸 (Grain size) 和薄膜片電阻 (sheet resistance) 等特性進行分析與研究，並將銦鎵鋅氧化物薄膜製作成電晶體元件，進行電晶體元件“電性特性的分析”與“直流劣化特性分析”。最後，因不具通道保護層的電晶體元件會與環境中的水氧產生反應，故我們使用PECVD於200 °C下沈積SiNx與SiOx於銦鎵鋅氧化薄膜電晶體上，探討當電晶體元件加上保護層時其對元件電性的影響。

In this thesis, we have successfully developed a thin film transistors (TFT) using a novel material amorphous Indium-Gallium-Zinc-Oxide (a-IGZO) as semiconductor layer, with high carrier mobility. The use of IGZO-based material can increases the field-effect mobility of TFT devices, the aperture of AMLCD panel and releases the issue of photo-excited leakage current. In this work the a-IGZO film was deposited on a glass substrate by sputtering Indium-Gallium-Zinc-Oxide target in DC glow discharge plasma of an argon/oxygen mixture. We changed the power of DC sputter and substrate move rate to adjust the uniformity of the a-IGZO film. Also, the conductivity and carrier concentration were controlled by adjusting the flux of the mixture oxygen during film deposition and thermal annealing temperatures. An optimal IGZO film deposition condition was finally established at room temperature for the IGZO TFTs. The benefit of using the DC sputter system possesses the feasibility and varieties to easily adjusting the optimal rate of a-IGZO for TFTs. Several material analysis techniques, such as AFM, XRD, SEM, Four-Point Probe, and etc. were utilized to discussing the crystallization, grain size, and sheet resistance of a-IGZO films. Electrical characteristics and conduction mechanisms of a-IGZO TFT devices were also investigated by I-V characteristic analysis and DC bias stress stability. Finally, the ambient effect was discussed. The water molecule absorption dominates the a-IGZO ambient interaction in ambience. The SiNx or SiOx passivation layer was deposited by PECVD at 200 °C. Furthermore, their performance such as environmental stability is investigated.