制备工艺以及退火处理对ZnO-TFT性能的影响

发布时间：2018-06-25 12:44

  本文选题：ZnO-TFT + 射频磁控溅射　； 参考：《深圳大学》2015年硕士论文

【摘要】：Zn O基薄膜晶体管(Thin Film Transistor,TFT)因其适合低温生长、具有较高迁移率和透明性等特点,很大可能取代传统的硅基TFT成为下一代显示背板技术的主流。利用射频磁控溅射法在室温下制备Zn O薄膜时,未经处理的薄膜载流子浓度较大、结晶质量差,当用作TFT器件的有源层时,会恶化器件的综合性能或者使器件呈现耗尽型模式。因此,本论文通过优化Zn O有源层的制备工艺和后期退火处理来调控有源层的输运特性,从而提高器件的综合性能。本论文采用底栅顶接触的TFT器件结构,在Si O2/p-Si衬底上利用磁控溅射法制备Zn O薄膜作为器件的有源层,以重掺杂p型硅衬底作为器件的栅极,利用掩膜板蒸镀法形成Al电极图案作为器件的源漏电极,从而制备出完整的TFT器件。Zn O-TFT器件进行空气退火后,器件的综合性能随退火温度的升高先变好后变差。器件在400℃空气退火后的综合性能最佳,场效应迁移率为2.7cm2/Vs,电流开关比达到5.0×105,阈值电压为4.6V,亚阈值摆幅为1.0V/Dec。分析表明,空气退火后,有源层中的吸附氧和Oi等受主类缺陷增加,有效降低了Zn O有源层中的载流子浓度,空气退火同时改善了有源层的结晶质量,减少了有源层和绝缘层界面处的表面缺陷态密度,结果栅压对沟道电流的调控能力变强,从而提高了器件的性能。增加退火温度到500℃,有源层中的氧相关受主类缺陷较多,它们对电子的散射和俘获作用变得很强,表面缺陷态密度增大,导致器件的综合性能下降。更高的退火温度会对器件的绝缘层造成损伤,最终导致器件失效。不通氧制备的Zn O-TFT由于载流子浓度太高,器件的输出曲线呈现出电阻效应。在溅射气氛中通入极少量的氧(O2:Ar=0.5:50sccm),有源层中氧相关受主类缺陷会增加,载流子浓度减小到一个相对合理的范围,器件的性能相对较好,场效应迁移率为0.05cm2/Vs、开关比为8.6×104、阈值电压为28V、亚阈值摆幅为11V/Dec。当通氧量增加时,氧相关受主类缺陷会过多,它们对电子的俘获和散射作用变得很强,栅压对沟道电流的调控能力变差,导致器件的综合性能下降。在提高Zn O-TFT综合性能方面,溅射气氛中通入氧气相比后期空气退火处理而言效果要差。通氧制备的Zn O-TFT经过N2退火后,一方面有源层中的氧相关受主缺陷减少,它们对电子的俘获和散射作用减弱,同时薄膜的结晶质量变好;另一方面Al电极与有源层的接触得到改善,提高了电子的传输能力,从而使得器件的综合性能提高。300℃退火后的器件综合性能最优,场效应迁移率为1.8cm2/Vs,开关比为1.43×106,阈值电压为24V,关态电流为5×10-11A,亚阈值摆幅为5.5V/Dec。但随退火温度的继续增加,载流子浓度进一步增大,器件的关态电流也会增大,开关比明显下降。500℃退火后器件由增强型转变为耗尽型。
[Abstract]:Due to its characteristics of high mobility and transparency, ZnO-based TFT (thin Film Transistor TFT) is likely to replace the traditional silicon based TFT as the mainstream of the next generation display backplane technology due to its high mobility and transparency. When Zn O thin films were prepared by RF magnetron sputtering at room temperature, the untreated thin films were characterized by high carrier concentration and poor crystallization quality. When used as active layers of TFT devices, the comprehensive properties of TFT devices would be deteriorated or the devices would exhibit depleted mode. Therefore, in this thesis, the transport characteristics of Zno active layer can be adjusted by optimizing the preparation process of Zno active layer and post-annealing treatment, so as to improve the comprehensive performance of the device. In this thesis, ZnO thin films are fabricated on Sio _ 2 / p-Si substrate by magnetron sputtering method, and heavily doped p-type silicon substrate is used as the gate of the device. The Al electrode pattern was formed by the mask plate evaporation method as the source and leakage electrode of the device, and the integrated properties of the TFT device, ZnO-TFT device, after air annealing, first improved and then deteriorated with the increase of annealing temperature. After annealing at 400 鈩，

本文编号：2065970