柔性衬底上α-IGZO TFT器件的制备与稳定性研究

发布时间：2018-06-27 10:01

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

【摘要】：柔性显示器件是未来显示技术领域的一个热门研究方向,而与此同时非晶铟镓锌氧化物薄膜晶体管(α-IGZO TFT)则因其相比传统的非晶硅薄膜晶体管具有迁移率高、均匀性好、可以大面积低温制备等优点被视为后者的潜在代替者,对于柔性衬底上的非晶铟镓锌氧化物薄膜晶体管的研究长期以来受到了各国研究者们的关注。我们利用射频磁控溅射、等离子体增强化学气相沉积法(PECVD)、热蒸发沉积等镀膜技术,完成了在柔性衬底聚酰亚胺(polyimide,PI)薄膜表面制备α-IGZO TFT器件的工作,针对存在的相关问题进行了工艺上的改良,并且探索了改善方案的工艺参数与TFT器件电学性能及稳定性之间的关系。采用叠层SiNx/SiO2薄膜作为绝缘层薄膜的方法制备了柔性衬底上α-IGZO TFT器件。由于SiNx材料具备更高的介电常数而SiO2材料与IGZO薄膜有着更好的界面接触,通过两者厚度的合理搭配找到最优的工艺参数(SiNx/SiO2 200nm/50nm),我们得到了比采用同等厚度的单层SiNx或者SiO2绝缘层器件更好的柔性α-IGZO TFT器件性能,并且取得更好的弯曲及偏压稳定性。针对柔性衬底容易在薄膜本征应力的影响下发生形变而在制备过程中造成不良影响的问题,通过对PECVD制备SiNx和SiO2薄膜的工艺进行摸索,找到高低频配比时间与薄膜应力关系,在叠层SiNx/SiO2水氧隔绝层的制备过程中通过工艺组合找到应力平衡的最优参数实现最终器件的整体应力平衡,并同时取得最佳的器件性能和稳定性。对柔性衬底上α-IGZO TFT器件的退火进行了研究,发现将进行过一次大气退火的器件在冷却后进行二次大气退火可以取得很大的改善效果,有更高的饱和迁移率(3.9 cm2/V·s)、更小的亚阈值摆幅(1.27 V/decade)和更好的稳定性,针对这种改善我们通过退火工艺比对找到了最优工艺参数,并且通过数据分析和相关测试结果确认了这种改善来自于二次退火对IGZO薄膜造成的影响。
[Abstract]:Flexible display devices are a hot research field in the field of display technology in the future, while amorphous indium gallium zinc oxide thin film transistors (伪 -IGZO TFT) have higher mobility and better uniformity than traditional amorphous silicon thin film transistors. The advantages such as large area low temperature fabrication are regarded as potential substitutes for the latter. The research of amorphous indium gallium zinc oxide thin film transistors on flexible substrates has been paid much attention by researchers all over the world for a long time. Using RF magnetron sputtering, plasma enhanced chemical vapor deposition (PECVD) and thermal evaporation deposition techniques, 伪 -IGZO TFT devices have been fabricated on the surface of polyimide (Pi) thin films on flexible substrates. In order to solve the related problems, the relationship between the process parameters of the improved scheme and the electrical properties and stability of TFT devices is explored. 伪 -IGZO TFT devices on flexible substrates were fabricated by using laminated SiNx / SiO2 thin films as insulating films. Because of the higher dielectric constant of the SiNx material and the better interface contact between the Sio _ 2 material and the IGZO film, By finding the optimal process parameters (Sinx / SiO2 200nm/50nm), we obtain better flexible 伪 -IGZO TFT devices with better bending and bias stability than single-layer SiNx or SiO2 insulator devices with the same thickness. In order to solve the problem that flexible substrates are easily deformed under the influence of intrinsic stress of thin films and have adverse effects in the preparation process, the relationship between the time of high and low frequency ratio and the stress of thin films is found by exploring the process of PECVD preparation of SiNx and Sio _ 2 films. The optimum parameters of stress balance are found through the process combination during the preparation of the layered SiNx / Sio _ 2 water-oxygen insulator layer. The overall stress balance of the final device is realized, and the optimal device performance and stability are obtained at the same time. The annealing of 伪 -IGZO TFT devices on flexible substrates is studied. We have higher saturation mobility (3.9cm ~ 2 / V s),) and better stability with a smaller subthreshold swing (1.27V / decade). For this improvement, we find the optimal process parameters through annealing process comparison. The effect of secondary annealing on IGZO thin films is confirmed by data analysis and related test results.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN321.5

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