基于a-IGZO薄膜材料的柔性半导体器件

发布时间：2018-07-12 19:14

  本文选题：铟镓锌氧化物 + 薄膜晶体管　； 参考：《山东大学》2015年硕士论文

【摘要】：当今电子信息行业的发展迅速,而电子元器件产业是基础,因此发展也异常的快。而薄膜晶体管(TFT)因为在显示器方面的关键作用,它的研发历来都是实验室和企业的研究重点。然而随着社会的发展,传统的半导体器件无法适应新的要求,例如形状可延展、可弯曲、透明等,在此情况下柔性半导体器件越来越受到人们的重视。柔性半导体器件方面,衬底选择是关键,本论文经过综合文献调研,从几种最常见也是被应用最多的柔性衬底材料之中,选择聚酰亚胺(PI)胶带作为柔性衬底,并且粘附在表面有一层300 nm二氧化硅的硅片(SiO2/Si)衬底上,后面简称硅片衬底。从TFT的结构设计出发,综合考虑了器件的性能与测试的稳定性,本论文选择了底栅顶接触结构。至于TFT最为关键的有源层,本论文选择了非晶铟镓锌氧化物(a-IGZO),主要原因是因为其具备高迁移率、高稳定性、透光率高、低温下易制备等特点。考虑了样品需要折叠弯曲的性能,绝缘层选择旋涂有机PI溶液制成薄膜来代替传统器件中易于断裂的SiO2、Si3N4等材料。制备柔性a-IGZO TFT的过程中,通过改变栅极金属材料,还有在绝缘层PI与有源层a-IGZO之间增加缓冲层,逐渐制作出了有一定特性的TFT器件。然后通过对器件进行不同温度退火并测试ID-VD与ID-VG曲线,选取了最佳的退火温度为200℃。确定退火温度后,在同一溅射环境下通过调整了IGZO薄膜的厚度来改变器件的性能,发现90 W、3min、纯Ar(流量为20 sccm)情况下,器件性能测试出最佳性能。为了提高器件的优异的特性,再次通过改进缓冲层得到了最优异的器件,使其迁移率达到3.49 cm2/Vs,亚阈值摆幅为3.45 V/decade,电流开关比为3.5E+6 A。PI胶带本身胶粘性比较高,后面经过制作工艺过程中高真空使其非常难以剥离,因此本论文选择在硅片衬底上旋涂一层聚甲基丙烯酸甲酯(PMMA)溶液,然后粘附胶带。由于PMMA中不可避免混有杂质,所以在后面的加温过程中会引起PI胶带的起伏而导致器件变差,但可以成功剥离,剥离后迁移率为0.30cm2/Vs,亚阈值摆幅为4.65 V/decade,电流开关比为4.6 E+5 A。新的器件选择在硅片上旋涂PMMA溶液形成薄膜,旋涂PI溶液形成薄膜作为柔性衬底,然后在表面制作TFT器件。完成后泡入丙酮溶液使PMMA溶解,以PI为衬底的器件漂浮在丙酮溶液里。经过尝试并且成功制作几个微米量级的超薄柔性器件,使其可以粘附在任何柔性材料上工作,漂浮前后性能基本不变,表明这种方式制作柔性器件是成功的。
[Abstract]:Nowadays, the electronic information industry is developing rapidly, and the electronic components industry is the foundation, so the development is very fast. The thin film transistor (TFT) has always been the focus of laboratory and enterprise research because of its key role in display. However, with the development of society, traditional semiconductor devices can not adapt to new requirements, such as extensible shape, bending, transparency and so on. In this case, flexible semiconductor devices have attracted more and more attention. Substrate selection is the key to flexible semiconductor devices. In this paper, polyimide (Pi) tape is selected as flexible substrate from several most common and widely used flexible substrate materials. And there is a 300 nm silicon dioxide wafer (Sio _ 2 / Si) on the surface, which is referred to as the silicon wafer substrate. Starting from the structure design of TFT and considering the performance and stability of the device, the bottom gate top contact structure is selected in this paper. As for the most important active layer of TFT, amorphous indium gallium zinc oxide (a-IGZO) is chosen because of its high mobility, high stability, high transmittance and easy preparation at low temperature. Considering the properties of the samples which need to be folded and bent, the insulator chooses the spin coated organic Pi solution to make thin films to replace the materials such as Sio _ 2 and Si _ 3N _ 4, which are easy to fracture in traditional devices. In the process of preparing flexible a-IGZO TFT, by changing gate metal material and adding buffer layer between Pi and a-IGZO, a TFT device with certain characteristics has been fabricated. Then, by annealing the device at different temperatures and measuring the ID-VD and ID-VG curves, the optimum annealing temperature is 200 鈩，

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