基于态密度模型的铟镓锌氧化物薄膜晶体管的仿真研究

发布时间：2018-09-01 08:35

【摘要】：TFT作为平板显示的核心器件,是影响显示效果的关键。利用a-IGZO材料作为有源层的TFT器件与传统的硅基TFT相比具有制作温度低、均一性好、透光性强、以及可制作于柔性衬底等诸多优势,目前是国内外学者广泛研究的热点问题。本文从IGZO材料特性入手建立IGZO-TFT器件模型,对双有源层器件进行参数优化,并分析有源层间的界面问题,旨在为双有源层IGZO-TFT的后续设计和制作提供参考。首先,我们利用MS软件分别对ZnO、有氧空位的ZnO、原子交替型和列交替型两种结构的IGZO材料进行了模拟仿真,通过对比各种材料的能带结构、态密度,得出了IGZO材料中各类原子对能带结构和态密度的影响。我们发现IGZO的导带底主要由金属原子的s轨道电子贡献,其中贡献最大的是In原子的5s2轨道,而Ga原子具有抑制氧空位的能力。同时由于In的5s2轨道具有球形对称的特点,IGZO材料对结构重构不具有敏感性。其次,我们基于态密度模型利用TCAD软件对IGZO-TFT进行了仿真,同时与实验所得数据进行对比,验证了模型的正确性。然后我们对器件进行了优化,我们发现有源层厚度为20nm、沟道长度为30μm、绝缘层厚度为60nm的IGZO-TFT器件具有较好的器件性能。最后给出了实际的工艺结构图。最后,我们基于以上模型对双有源层IGZO-TFT进行了模拟仿真,研究了有源层厚度变化,及有源层间界面位置对器件性能的影响。在理想情况下,我们得到了阈值电压Vth=-0.89V、亚阈值摆幅SS=0.27、开关电流比Ion/Ioff=6.98×1014的高性能器件。同时我们发现界面位置在主要导电区边缘时,器件性能最佳。
[Abstract]:As the core device of flat panel display, TFT is the key to the effect of display. Compared with traditional silicon based TFT, TFT devices using a-IGZO as active layer have many advantages, such as low temperature, good uniformity, strong transmittance, and can be fabricated on flexible substrates, etc. At present, it is a hot issue widely studied by scholars at home and abroad. Based on the characteristics of IGZO materials, this paper establishes a IGZO-TFT device model, optimizes the parameters of dual-active layer devices, and analyzes the interface between active layers. The purpose of this paper is to provide a reference for the subsequent design and fabrication of dual-active layer IGZO-TFT. First of all, we use the MS software to simulate the ZnO, atom alternating structure and column alternating type IGZO material of ZnO, aerobic vacancy, and compare the energy band structure and the density of states of each kind of material by comparing the energy band structure and the density of states of each kind of material. The effects of various atoms on the band structure and density of states in IGZO materials are obtained. We find that the bottom of the conduction band of IGZO is mainly contributed by the S-orbital electrons of metal atoms, and the most important contribution is the 5s2 orbital of the In atom, while the Ga atom has the ability to inhibit the oxygen vacancy. At the same time, because of the spherical symmetry of In's 5s2 orbit, IGZO material is not sensitive to structural reconstruction. Secondly, we use the TCAD software to simulate the IGZO-TFT based on the density of states model, and compare with the experimental data to verify the correctness of the model. Then we optimize the device. We find that the IGZO-TFT device with active layer thickness of 20 nm, channel length of 30 渭 m and insulation layer thickness of 60nm has good performance. Finally, the actual process structure diagram is given. Finally, we simulate the dual-active layer IGZO-TFT based on the above model, and study the influence of the thickness of the active layer and the interfacial position of the active layer on the performance of the device. Under ideal conditions, we have obtained a high performance device with threshold voltage Vth=-0.89V, sub-threshold swing SS=0.27, switch current ratio Ion/Ioff=6.98 脳 1014. At the same time, we find that the device has the best performance when the interface is located at the edge of the main conductive region.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN321.5

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