共溅射Al-Zn-Sn-O薄膜晶体管性能的研究

发布时间：2018-03-26 20:17

本文选题：氧化物薄膜晶体管　切入点：共溅射　出处：《吉林大学》2015年硕士论文

【摘要】：随着未来显示逐渐向高分辨率、大面积以及柔性化方向的发展，对背板技术性能要求更高。以铟镓锌氧化物薄膜晶体管为代表的氧化物薄膜晶体管以其场效应迁移率高、透过率高、大面积均匀性好等优点，得到人们广泛关注。此外，以IGZO薄膜晶体管作为背板技术制备的显示面板还具有功耗低的优点。然而，IGZO中含有稀有元素In、Ga，不利于降低成本，因此研究不含稀有元素、且性能能与IGZO薄膜晶体管相比拟的氧化物薄膜晶体管具有重要的意义。本文从稀有元素替代角度出发，根据IGZO薄膜中载流子传输机理，采用Al、Sn分别替代IGZO薄膜中的Ga、In元素。并采用与现代工业生产相兼容的磁控溅射工艺，通过三靶磁控共溅射Al2O3、ZnO和SnO2靶材的方式，制备了Al-Zn-Sn-O（AZTO）薄膜及其薄膜晶体管，并对AZTO薄膜及其薄膜晶体管的性能进行了研究，具体工作内容如下： 1、通过调节溅射过程中Al2O3的沉积功率，制备了在不同Al2O3沉积功率下AZTO薄膜。结果显示，在不同Al2O3沉积功率下，所制备的AZTO薄膜都是非晶的，并且均具有较高的透过率，单层薄膜在人眼最敏感波长（550nm）处的透过率均在85%以上。 2、我们进一步制备了在不同Al2O3沉积功率下AZTO薄膜晶体管，研究了不同Al2O3含量对器件性能的影响。结果表明，随着Al2O3沉积功率的增加，器件的迁移率逐渐降低，阈值电压逐渐增大，但器件的转移特性得到了有效的改善，并且开关比显著提高。分析得出，Al在AZTO薄膜中充当着抑制载流子的作用，就像IGZO中的Ga一样。当Al2O3溅射功率为20W时，获得了较好的器件性能。通过冷场发射扫描电子显微镜(JSM-7500F)测得，当Al2O3溅射功率为20W时，未退火AZTO薄膜中Zn、Sn、Al、O的原子含量分别为17%、3%、2%、78%。 3、我们制备了不同有源层厚度的器件，研究了有源层厚度对器件性能的影响。结果表明，有源层厚度对器件性能的影响很大，当厚度太薄时，载流子数量太少，迁移率过低；而当厚度过厚时，一方面会增大载流子注入电阻，另一方面厚度过厚将会引起载流子数量过多，发生散射，结果都会使得迁移率有所下降。当有源层厚度为45nm时，我们获得了最优的器件性能。 4、对上述获得的最佳器件，我们进一步研究了正向偏压下器件的稳定性。结果发现，在正向偏压应力下，器件的阈值电压发生了正向漂移。这是由于被栅电压吸引到沟道层与绝缘层界面处的自由载流子被界面处的负电荷陷阱俘获，，或者是注入到绝缘层体内，被体内的陷阱捕获。所以载流子数量降低，阈值电压发生正向漂移。
[Abstract]:With the development of high resolution, large area and flexibility in the future display, the technical performance of back plate is more demanding. The field effect mobility of oxide thin film transistors represented by indium gallium zinc oxide thin film transistors is higher than that of indium gallium zinc oxide thin film transistors. The advantages of high transmittance and good uniformity in large area have attracted wide attention. In addition, the display panel fabricated with IGZO thin film transistor as backplane technology also has the advantage of low power consumption. Therefore, it is of great significance to study oxide thin film transistors which contain no rare elements and whose properties are comparable to those of IGZO thin film transistors. In this paper, based on the carrier transport mechanism of IGZO thin films, the Gain elements in IGZO thin films are replaced by Alnion Sn, and the magnetron sputtering process compatible with modern industrial production is adopted. Al-Zn-Sn-OZTOA) thin films and their thin film transistors were prepared by three-target magnetron co-sputtering of Al _ 2O _ 3ZnO and SnO2 targets. The properties of AZTO thin films and their thin film transistors were studied. The main work is as follows:. 1. By adjusting the deposition power of Al2O3 during sputtering, AZTO thin films were prepared under different Al2O3 deposition power. The results show that the AZTO films prepared under different Al2O3 deposition power are amorphous and have high transmittance. The transmittance of monolayer films is over 85% at the most sensitive wavelength of 550 nm. 2. We have prepared AZTO thin film transistors with different Al2O3 deposition power, and studied the effect of different Al2O3 content on the device performance. The results show that the mobility of the devices decreases with the increase of Al2O3 deposition power. The threshold voltage increases gradually, but the transfer characteristics of the device are improved effectively and the switching ratio is significantly improved. It is found that Al acts as a carrier suppressor in AZTO films, just like Ga in IGZO. When the sputtering power of Al2O3 is 20 W, Good device properties have been obtained by using a cold field emission scanning electron microscope (JSM-7500F). When the sputtering power of Al2O3 is 20W, the atomic content of ZnSn-Sn-Al _ 2O in unannealed AZTO thin films is 17 / 3 / 7500F, respectively. 3. The influence of the thickness of the active layer on the performance of the device is studied. The results show that the thickness of the active layer has a great effect on the performance of the device. When the thickness is too thin, the number of carriers is too small and the mobility is too low. When the thickness is too thick, on the one hand, the carrier injection resistance will increase, and on the other hand, the thickness of the carrier will lead to excessive carrier number and scattering, resulting in a decrease in mobility. When the thickness of the active layer is 45nm, We have obtained the optimal device performance. 4. For the optimum device obtained above, we further study the stability of the device under forward bias. The threshold voltage of the device is positively shifted because the free carrier attracted by the gate voltage to the interface between the channel layer and the insulating layer is captured by the negative charge trap at the interface or injected into the insulating layer. The number of carriers is reduced and the threshold voltage is positively drifted.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN321.5

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