铟镓锌氧化物薄膜晶体管的制备和性能研究

发布时间：2018-06-06 02:39

  本文选题：IGZO-TFT + 磁控溅射　； 参考：《电子科技大学》2015年硕士论文

【摘要】：非晶铟镓锌氧化物(Indium Gallium Zinc Oxide,IGZO)具有迁移率高、均一性好等特点,并且在可见光区有较高的光透过率,有望实现全透明以及柔性显示,是新一代氧化物薄膜晶体管中应用最广泛,也是最主流的有源层材料。本论文采用直流磁控溅射方法制备了IGZO薄膜并以其为有源层制备了IGZO-TFT,具体的研究内容包括:(1)采用直流磁控溅射方法制备IGZO薄膜,研究了溅射功率、溅射时间对薄膜的可见光范围内光学透过率的影响。结果表明直流磁控溅射制备出的IGZO薄膜的可见光区光透过率基本保持在80%左右,在溅射功率为180 W,溅射时间为200 s下制备的薄膜光透过率高达89.73%。然后利用SEM、AFM观察并分析了不同溅射功率、不同溅射腔气压和不同氧分压下制备得到的IGZO薄膜表面形貌,SEM图像表明溅射功率在180-200 W范围内,2 mTorr溅射腔气压下,IGZO薄膜表面平整,缺陷较少;AFM图像表明随着氧分压的增大,薄膜表面越平整,粗糙度越小,并且在衬底上旋涂一层有机溶液后再沉积IGZO薄膜的粗糙度要比在衬底上直接沉积的小很多。最后通过XRD测试验证了直流磁控溅射的IGZO薄膜为非晶态。(2)利用旋涂法分别制备以PMMA、PVA为绝缘层,直流磁控溅射IGZO为有源层的底栅顶接触型IGZO-TFT器件。研究了氧分压、缓冲层、绝缘层厚度以及退火处理对IGZO-TFT器件性能的影响。对于以PMMA为绝缘层、IGZO为有源层的TFT器件,研究结果表明氧分压增加会导致载流子迁移率先增大后减小,氧分压为1.2%时,载流子迁移率最大,为0.84 cm2·V-1·s-1。采用低功率磁控溅射超薄IGZO缓冲层(5 nm)能降低电子陷阱和薄膜粗糙度,优化绝缘层和有源层的界面态,提升有源层的成膜质量。对于以PVA为绝缘层、IGZO为有源层的TFT器件,研究结果表明随着绝缘层厚度的增加,载流子迁移率和电流开关比均呈现增大的趋势,并且器件的性能要优于以PMMA作为绝缘层时的。绝缘层厚度为800nm时,TFT器件性能最好,载流子迁移率为11.4 cm2·V-1·s-1,电流开关比为9.6×102,阈值电压为9.7 V。研究还表明经过退火处理的器件性能要比未退火处理的器件性能好,退火温度在200℃时最佳,此时器件的载流子迁移率为24.8 cm2·V-1·s-1,电流开关比为3.5×103,阈值电压为7.3 V。
[Abstract]:Indium Gallium Zinc oxide (IGZO) has the characteristics of high mobility, good uniformity and high optical transmittance in the visible region. It is expected to achieve full transparency and flexible display. It is the most widely used in the new generation of oxide thin film transistors. Is also the most mainstream active layer material. In this thesis, IGZO thin films were prepared by DC magnetron sputtering and IGZO-TFT thin films were prepared by using them as active layers. The specific research contents include: (1) DC magnetron sputtering method was used to fabricate IGZO thin films, and the sputtering power was studied. The influence of sputtering time on the optical transmittance in the visible range of the film. The results show that the optical transmittance of the IGZO thin films prepared by DC magnetron sputtering is about 80% in the visible region, and the transmittance of the films prepared at the sputtering power of 180W and the sputtering time of 200s is as high as 89.73g. Then the surface morphologies of IGZO films prepared under different sputtering power, different sputtering chamber pressure and different oxygen partial pressure were observed and analyzed by SEMMA-AFM. The results showed that the surface of IGZO thin films was flat in the sputtering power range of 180-200W / 2 mTorr sputtering cavity pressure. The results show that with the increase of oxygen partial pressure, the surface of the IGZO films is flat and the roughness is smaller, and the roughness of the IGZO films deposited on the substrates is much smaller than that on the substrates after spin-coating with an organic solution. Finally, the XRD test shows that the IGZO films deposited by DC magnetron sputtering are amorphous. (2) the bottom gate top contact IGZO-TFT devices with PMMA-PVA as insulation layer and DC magnetron sputtering IGZO as active layer are fabricated by spin-coating method. The effects of oxygen partial voltage, buffer layer, insulation thickness and annealing treatment on the performance of IGZO-TFT are studied. For TFT devices with PMMA as the insulating layer and IGZO as the active layer, the results show that the increase of oxygen partial pressure will lead to the increase of carrier migration first and then decrease, and the maximum carrier mobility of 0.84 cm2 V-1 s-1 when oxygen partial voltage is 1.2. The ultra-thin IGZO buffer layer (5 nm) prepared by low power magnetron sputtering can reduce the electron trap and the roughness of the film, optimize the interface state between the insulating layer and the active layer, and improve the film forming quality of the active layer. For TFT devices with PVA as the insulator and active layer, the results show that the carrier mobility and the current-switching ratio increase with the increase of the thickness of the insulating layer, and the performance of the device is better than that of the TFT device with PMMA as the insulator. When the thickness of insulation layer is 800nm, the device has the best performance, the carrier mobility is 11.4 cm2 V-1 s-1, the current-switching ratio is 9.6 脳 102, and the threshold voltage is 9.7 V. The results also show that the annealed device has better performance than the unannealed device. The annealing temperature is 200 鈩，

本文编号：1984668