低温金属氧化物薄膜晶体管的研制

Due to the high mobility and high opening rate, metal oxide TFT has become a hot spot of research at home and abroad and has made great progress, However, the key problem that can not be industrialized is the mobility of low temperature TFT can not meet the requirements of modern display such as 3D, and stability can not meet the practical needs. This project intends to prepare low temperature TFT by magnetron sputtering. Based on the factors such as electronegativity, ionic radius, mobility and stability, a new active material (such as IZTO, etc.), which is used to improve the mobility of low temperature TFT, is optimized for ns orbital metal cation oxides. The optimization of TFT preparation process, the preparation of high quality of the active layer and the insulation layer, reduce the defect density, can improve the mobility of low temperature TFT, improve the stability of the device. The insulation layer surface treatment (such as oxygen plasma treatment), reduce the defect density of the interface between the insulating layer and the active layer, the TFT leakage current and threshold voltage drift reduction, improve the stability of low temperature TFT, but also can reduce the defect density of the active layer, improve the mobility of low temperature TFT. The electrode can be optimized to improve ohmic contact and improve the stability of the device. The intermittent diffusion of the device can be used to reduce the interdiffusion of the device and improve the quality of the device. Explore the new TFT structure and preparation process, improve the performance of TFT.

金属氧化物TFT由于迁移率大、开口率高，已成国内外研究的热点并已取得了长足进步，但仍不能产业化的关键问题是低温TFT的迁移率还满足不了3D等现代显示器的要求，且稳定性也达不到实用化的需求。本项目拟用磁控溅射制备低温TFT；通过电负性、离子半径、迁移率和稳定性等因素优选ns 轨道金属阳离子氧化物新型有源层材料（如IZTO等），提高低温TFT的迁移率；优化TFT制备工艺，制备高质量的有源层和绝缘层，降低缺陷密度，可提高低温TFT的迁移率，改善器件的稳定性；通过绝缘层表面处理（如等离子体氧处理等），减少绝缘层与有源层界面的缺陷密度，使TFT泄漏电流和阈值电压漂移减少，提高低温制备TFT的稳定性，也可以减少有源层的缺陷密度，提高低温制备TFT的迁移率；优选电极，改善欧姆接触，提高器件稳定性；用间断间歇退火办法可减少器件多层间的互扩散，提高器件的质量；探索新型TFT结构和制备工艺，提高TFT的性能。

TFT是TFT-LCD和AMOLED等平板显示器的关键部件，目前主要是用a-Si TFT，由于其迁移率和开口率低等缺点，已不能满足大尺寸、高分辨率、超高清、高速的现代显示的需求。IGZO金属氧化物TFT具有迁移率和开口率高等优点成为替代a-Si TFT的理想器件，目前已进入显示器生产阶段。但是，这些金属氧化物TFT的制备温度高和迁移率低等仍不能满足3D等现代显示的需求。针对这些问题，我们用磁控溅射制备了五个氧化物材料体系TFT（IZTO:N、IZTO:(Li,N)和IZTO:W等体系TFT，ZTO:N等体系TFT，IZO:Li等体系TFT，IZAO:(Li,N)等体系TFT以及双活性层结构IZO:(Li,N)/IZO:(Al,N)等体系TFT），通过改变沉积条件、退火条件和绝缘层表面表面处理等获得主要研究结果如下：.1.制备出了IZAO:(Li,N)TFT。在退火温度为265℃下，器件的迁移率为45.6cm2/Vs，亚阈值摆幅为0.37V/decade，阈值电压为0.1V，开关比为3×108，关态电流为6×10-12A。.2.制备出了IZTO:N TFT。在退火温度为275℃下，器件的迁移率为37.6cm2/Vs，亚阈值摆幅为0.38V/dec.，阈值电压为1.4V，开关比为1×109，在1000s下PBS和NBS分别为+13.6V和-3.4V。.3.制备出了IZO:Li TFT。在300℃退火温度下，器件的迁移率为55.3cm2/Vs，亚阈值摆幅为0.74V/dec.，开关比约为1×108。.4.制备出了IZTO:(Li,N)TFT。在退火温度为300℃下，器件的迁移率为39.5cm2/Vs，阈值电压为3.2V，亚阈值摆幅为0.6V/dec，开关比为3.5×109。.5.制备出了IZTO:W TFT。在退火温度为300℃下，器件的迁移率为41cm2/Vs，阈值电压为2.4V，开关比为6.8×108，亚阈值摆幅为0.5V/dec.。.6.制备出了双有源层的IZO:(Li,N)/IZO:(Al,N)TFT。在温退火300℃下，器件的迁移率为49.8cm2/Vs，开关比为1.7×109，亚阈值摆幅为0.61V/decade。