铪铝氧化物复合绝缘介质薄膜及高迁移率锌铟锡氧化物薄膜晶体管的研究

发布时间：2018-02-04 13:42

本文关键词： 薄膜晶体管溶液法高k氧化物锌铟锡氧化物高迁移率　出处：《上海大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,基于透明氧化物半导体的薄膜晶体管(Thin Film Transistor,TFT)因其高透光率,高迁移率并在未来平板显示领域中有着潜在应用的特点而受到人们的广泛关注。目前,大部分TFT均是采用真空方法制备的,并且获得了良好的性能。但采用真空法制备TFT器件会有很多缺点。以磁控溅射制备TFT为例,其存在着制备工艺成本高和靶材利用率低等缺点,不利于大规模的使用。溶液法作为TFT制备的另一种方法,它不需要真空环境,它具有工艺简单,成本低和可以精确控制薄膜成分等优点,可以大规模生产。因此,采用溶液法制备TFT的研究正在逐年增多。本论文研究采用溶液法制备Hf O2,Al2O3和HAO作绝缘层和ZITO作有源层氧化物材料,并在此基础上制备出低压驱动的底栅顶接触结构的TFT器件,并研究其性能。本论文的主要工作如下:1.在制备绝缘层材料时,首先采用溶液法旋涂工艺制备了Hf O2和Al2O3介质薄膜,研究了不同温度退火后薄膜的结构和光电学性能,结果表明Hf O2薄膜具有漏电流高,击穿电场低和介电常数高的特点,而Al2O3薄膜正好相反,具有漏电流低,击穿电场高和介电常数低的特点。然后结合Hf O2和Al2O3制备出了HAO薄膜。研究发现,Hf/Al=2:1的HAO膜在500 o C退火后的相对介电常数为12.1,并且在2 MV/cm的电场强度下的漏电流密度为1.69×10-7 A/cm2。2.在采用溶液法制备ZITO有源层时,研究了不同退火温度对其的影响,并通过XPS,AFM等对其进行了表征。为了制备出底栅顶接触结构的TFT器件,研究了ZITO膜在PAN和草酸中的刻蚀速率。结果表明经过350 o C退火处理后的ZITO膜在温度为35 o C的PAN中的刻蚀速率几乎可以忽略不计。3.在溶液法成功制备绝缘层和有源层的基础上,制备出了低压驱动的底栅顶接触结构的TFT器件。并对ZITO-Hf O2 TFT,ZITO-Al2O3 TFT和ZITO-HAO TFT进行了分析讨论,重点研究了ZITO-HAO TFT。研究发现,经过500°C退火处理的ZITO-HAO器件具有开关比高(7.2×106),阈值电压低(-0.6 V),亚阈值摆幅小(87 m V/decade)和饱和迁移率高(13.5 cm2/Vs)的特点.偏压稳定性测试表明HAO和ZITO的同时使用使得TFT器件具有很好的稳定性。
[Abstract]:In recent years, thin Film transistors based on transparent oxide semiconductors (TFT) have been developed for their high transmittance. High mobility and potential applications in the field of flat panel display in the future have attracted widespread attention. At present, most of the TFT is prepared by vacuum method. And good performance has been obtained. However, there are many shortcomings in fabricating TFT devices by vacuum method. Taking magnetron sputtering as an example, there are many disadvantages such as high cost of preparation process and low utilization ratio of target materials. As another method of TFT preparation, solution method does not need vacuum environment. It has the advantages of simple process, low cost and accurate control of film composition. Therefore, the preparation of TFT by solution method is increasing year by year. Al2O3 and HAO are used as insulating layer and ZITO as active layer oxide material. On this basis, a low-voltage driven TFT device with bottom gate top contact structure is fabricated. The main work of this thesis is as follows: 1. In the preparation of insulating layer materials, HF _ 2 and Al2O3 dielectric thin films were prepared by solution spin-coating process. The structure and optoelectronic properties of the films annealed at different temperatures were studied. The results show that HFO _ 2 thin films have the characteristics of high leakage current, low breakdown electric field and high dielectric constant, whereas the Al2O3 films are just the opposite. It has the characteristics of low leakage current, high breakdown electric field and low dielectric constant. Then, HAO thin films were prepared by combining HFO _ 2 and Al2O3. The relative dielectric constant of Hf/Al=2:1 HAO films annealed at 500o C is 12.1. The leakage current density is 1.69 脳 10 ~ (-7) A / cm ~ (-2) at the electric field intensity of 2 MV/cm. The active layer of ZITO is prepared by solution method. The effects of different annealing temperatures on the structure were investigated and characterized by XPS-AFM. In order to fabricate the TFT devices with bottom gate top contact structure. The etching rate of ZITO film in PAN and oxalic acid was studied. The results show that the temperature of ZITO film annealed at 35o C is 35 o. The etching rate in C PAN is almost negligible. 3. On the basis of the successful preparation of insulating layer and active layer by solution method. TFT devices with bottom gate top contact structure driven by low voltage are fabricated, and ZITO-Hf O 2 TFT is obtained. ZITO-Al2O3 TFT and ZITO-HAO TFT were analyzed and discussed, especially ZITO-HAO TFT. The ZITO-HAO device annealed at 500 掳C has a high switching ratio of 7.2 脳 10 ~ 6N and a low threshold voltage of -0.6 V). Sub-threshold swing (87 m V / L decadea) and high saturation mobility (13.5 cm 2 / V s). The bias stability test shows that the use of both HAO and ZITO makes TFT devices have good stability.
【学位授予单位】：上海大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN321.5

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