标题: | 非晶态氮掺杂氧化铟镓锌薄膜电晶体特性之研究 Investigation on Amorphous Nitrogenated Indium Gallium Zinc Oxide Thin Film Transistors Application |
作者: | 廖于德 Liao, Yu-Tei 施敏 刘柏村 Sze, Min Liu, Po-Tsun 电子工程学系 电子研究所 |
关键字: | 薄膜电晶体;氮掺杂;氧化铟镓锌;TFT;IGZO:N;nitrogenated |
公开日期: | 2014 |
摘要: | 非晶态氧化半导体(Amorphous Oxide Semiconductors: AOSs) 具有高载子迁移率而且可低温沉积、可挠曲、透明性以及均匀度佳等特点已受到广泛的重视。目前被研究的氧化半导体有ITO、IZO、TiO2、ZnO、In2O3、Ga2O3、IGO、a-IGZO等。其中以透明非晶态氧化铟镓锌(Amorphous InGaZnO: a-IGZO)薄膜当作主动层(Active layer)的薄膜电晶体(Thin Film Transistors: TFTs),具有载子迁移率与可靠度比传统氢化非晶矽薄膜电晶体(a-Si:H TFT)高、均匀性优于低温复晶矽薄膜电晶体(Low Temperature Polycrystalline Silicon TFT: LTPS TFT),而且可低温制程。因此非晶态氧化铟镓锌薄膜(IGZO)电晶体具有取代氢化非晶矽薄膜电晶体与低温复晶矽薄膜电晶体来制作主动矩阵有机发光显示器(Active Matrix Organic Light Emitting Display: AMOLED)的潜力。但是氧化铟镓锌(IGZO)薄膜存在着一些本质上的缺点。例如对环境中的水、氧很敏感进而影响元件的稳定性。并且,氧化铟镓锌薄膜电晶体长时间操作的可靠度也是需要探讨。文献得知,非晶矽薄膜掺入氮后,本身对环境变得较不敏感。因此本研究中我们使用直流溅镀(DC Sputtering)沉积氧化铟镓锌薄膜薄膜,并于薄膜沉积过程中混入氮气制成非晶态含氮氧化铟镓锌(a-IGZO:N)薄膜,之后分别进行进行电特性与材料特性的分析与探讨。 由实验结果显示随着通入氮气量增加,元件的电特性及可靠度都随之下降。分析实验数据我们推论电特性下降可能原因为主动层(a-IGZO:N)和介电层(SiO2)间的通道品质不稳定。藉由低频杂讯分析仪(Low-Frequency Noise measurement)的分析结果证实通道缺陷密度随通氮量增加而上升。之后我们选择于薄膜沉积前先以氧化亚氮(N2O)电浆处理介电层表面,实验结果显示电特性获得显着改善。并进一步发现于薄膜沉积过程中通入适量的氮气,可以增加薄膜的导电性,提高载子迁移率并且有效的提升元件在长时间操作下的可靠度。研究中,我们发现先以电浆处理介电层而后于氧化铟镓锌薄膜沉积制程通入适量氮气形成非晶态含氮氧化铟镓锌薄膜电晶体,成功将载子迁移率提升至19.21 cm2/V s,因此极有潜力成为下个世代的主流显示技术。 Amorphous oxide semiconductors (AOSs) are attracted much attention due to high mobility, low temperature deposition, flexible, transmission, and uniformity. It has been investigated of AOSs, such as ITO, IZO, TiO2, ZnO, In2O3, Ga2O3, IGO, a-IGZO, etc. Especially, the thin film transistors (TFTs) with a-IGZO thin film as active layer perform higher mobility and better reliability than conventional hydrogenated amorphous silicon TFT (a-Si:H TFT). Therefore, the a-IGZO TFTs have the potential to replace a-Si: H TFT and LTPS TFT forming Active Matrix Organic Light Emitting Display (AMOLED). However, a-IGZO there are some inherent defect, such as sensitive to water and oxygen in ambient environment thereby affect the device stability. The device reliability under GBS also has to be considered. In this work, we presents the electrical characteristics of the nitrogenated amorphous InGaZnO thin film transistor (a-IGZO:N TFT) for the first part. The a-IGZO:N film acting as a channel layer of a thin film transistor (TFT) device was prepared by DC reactive sputter with a nitrogen and argon gas mixture at room temperature. Experimental results show that TFT electric parameters and reliability degrade with increasing nitrogen flow rate due to in situ N doping method during a-IGZO:N film preparation may form an unstable interface between dielectric and channel layer and average interfacial trap density (Nt) increases with increasing nitrogen flow rate confirmed by Low-Frequency measurement analysis. For the second part, N2O plasma treatment is executed on the SiO2 dielectric surface to improve the instability behavior of the a-IGZO:N TFTs. The superior device characteristics of IGZO:N-based TFTs can be achieved. Moreover, the role of nitrogen doping has been investigated. With a proper amount of in situ nitrogen doping, nitrogen doped TFT can reduce the oxygen vacancy and total trap densities then demonstrate superior electric characteristics, improved reliability, and smaller falling-rate (FR). These results showed the application potentials of a-IGZO:N TFT device on flat panel display technology. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT070150176 http://hdl.handle.net/11536/76176 |
显示于类别: | Thesis |