臺灣大學: 電子工程學研究所劉致為徐國修Hsu, Kuo-HsiuKuo-HsiuHsu2013-04-102018-07-102013-04-102018-07-102011http://ntur.lib.ntu.edu.tw//handle/246246/256817近年來，利用非晶相銦鎵鋅氧化物(α-IGZO)做為薄膜電晶體(TFT)通道材料於Active Matrix Organic Light Emitting Diode (AMOLED)已經成為研究的趨勢。相較於傳統的非晶矽薄膜電晶體(α-Si TFTs)，α-IGZO有高的開/關比(on/off ratio) > 108和電子遷移率(Carrier Mobility) > 10 cm2/V-s。在製程上，可以在室溫中利用RF-sputter沉積通道材料α-IGZO並且可以有效的控制薄膜的均勻性。因此， α-IGZO 是下一代薄膜電晶體很好的通代材料。 在α-IGZO薄膜特性上，會隨著不同的成長環境以及退火處理有所差別。我們可以利用波長為325nm 的氦鎘雷射運用在 PL量測(Photoluminescence measurement)來分析α-IGZO薄膜能帶中的缺陷分布。從研究結果得知，α-IGZO薄膜 (厚度為100nm)的PL特性，接近450nm(~2.78eV)波段定義為能帶邊緣間的放射 (Band to Impurity) 。另外，伴隨著在850nm(~1.45eV)波段的地方則是缺陷到缺陷DAP (Donor to Acceptor Pairs)。低溫量測時，波段在575nm(~2.15eV)則會更明顯。利用不同退火溫度或不同退火氣體的條件下對α-IGZO薄膜的影響，並且運用PL量測來判斷DOS的變化。 對於元件穩定度測試，探討由於偏壓應力施加導致元件失真的原因以及物理機制。我們將對元件做一系列的量測分析，例如：電性分析、偏壓應力分析等等。然而，元件的可靠度測試以及物理特性分析就變得特別重要，對於N型α-IGZO TFTs而言，我們將會對於元件NBTI以及PBTI做基本的測試，並探討元件電性衰減的物理機制。對於下列量測方式與結果的分析對於元件的穩定度非常重要。然而，在先前已發表的文獻中已提出幾項原因以及模型理論，例如：電荷被氧化層捕捉、能帶間產生新的缺陷分布等等，解釋偏壓應力產生的臨界電壓偏移、汲極電流、電子遷移率次臨界斜率的衰退。在我們的研究上，將對於α-IGZO薄膜電晶體正偏壓和負偏壓的穩定度測試做詳細的量測以及分析。對於施加偏壓應力後的元件做變溫的量測技術，可以利用M-N法則(M-N Rule)的理論計算萃取出能帶中的缺陷分布以及數目。然而，利此方法所計算出來的缺陷分布，代入2-D的模擬分析此元件的特性以及物理意義。In the past years, there has been increasing interest in using amorphous indium gallium zinc oxide(a-IGZO) to the channel material of the thin-film transistors (TFTs) for Active Matrix Organic Light Emitting Diode (AMOLED). As compared to hydrogenated amorphous silicon (a-Si) TFTs, the a-IGZO TFTs have high on/off current ratio and high carrier mobility. In process, it is possible to deposit the channel material (a-IGZO) by RF sputter at the room temperature and control the uniformity. Therefore, a-IGZO is a major channel material candidate for the next generation TFTs. The structure and optical properties of a-IGZO thin films depend on the preparation methods, growth condition, and subsequent annealing treatment. The optical properties of the films were investigated by the use of photoluminescence (PL). PL spectra were measured by He–Cd laser with an excitation wavelength of 325 nm at room temperature. The strong shallow donor level to valence band emission was clearly observed at a wavelength of 450 nm (~2.78eV) accompanied with a weak broad deep emission peaking which is donor to acceptor pair emission (DAP) at around 850 nm (~1.45eV) for 100nm thick samples deposited by sputtering. At the low temperature measurement, the peak at 575nm (~2.15 eV) is the shallow trap level to valence band transition. It was found that the excitation related emission of a-IGZO thin films depends on annealing gas. The shallow donor level to valence band emission increases with the increase of annealing temperature and annealing time. To optimize the process conditions, PL is the most important analytical techniques to reveal the structure and sub-gap state. The reliability issues have become the most rising topic. However, the reliability problem of a-IGZO TFTs is even more complicated as compared to single crystalline MOSFETs and rarely investigated. The complete understanding of device degradation mechanisms is attractive and noteworthy. For n-channel a-IGZO TFTs, the negative and positive bias temperature instability for a-IGZO TFTs will be performed. For the practical application, the dynamic bias temperature stress will also be studied. The stress-induced sub-gap states will be extracted directly from the temperature-dependent field effect measurement (M-N rule). The 2-D simulation of a-IGZO TFTs based on proposed density of states (DOSs) model will be used to explain the physical mechanism.2614027 bytesapplication/pdfen-US非晶相銦鎵鋅氧化物薄膜電晶體光激發螢光頻譜M-N 法則偏壓穩定度a-IGZOTFTPLM-N ruleBTIthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/256817/1/ntu-100-R98943068-1.pdf