Study Of Indium Gallium Zinc Oxide Thin Film Transistors Using Magnetron Sputtering

In this paper, we fabricated thin film transister (TFT) with Indium Gallium Zinc Oxide (IGZO) as active layer and SiO2as gate insulator。We studied the impact of heat treatment andfilm thickness on the optical characteristics of IGZO film. We also inves-tigated the influence of oxigen partial pressure and heat treatment on the electrical cha-racteristics of IGZO-TFTs.(1)We deposited IGZO film using radio-frequency magnetron sputtering (RFMS), then analysed the optical transmisttance of IGZO film under different conditions. The result shows that the transmisstance slightly increased with increasing film thickness (40,80, and120nm), and that both annealing and substrate heating can increase the transmisstance.(2)We studied on the influence of different oxygen partial pressure (0%,3.3%, and6.7%) on the surface morphlogy of IGZO films using AFM tests, and found that the films are the smoothest under oxygen partial pressure of3.3%. Then we fabricated IG-ZO-TFTsunder different oxygen partial pressure (0%,3.3%, and6.7%). We found un-der oxygen partial of3.3%, the electrical characteristics of TFT is best, withlowest threshold voltage (-12.64V). highest carrier mobility (0.43cm2/Vs), and highest on/off ratio(～1.85x102).(3)We studied the influence of substrate heating and annealing onIGZO film mor-phology. AFM test shows that the surface of the films with200℃substrate heating are better than those annealed at200℃, and both of themare better than those of untreated. The subsequent IGZO-TFTs electrical tests show that compared with those of unan-nealed devices, the electric characteristics of IGZO-TFTs are improved by annealing, with mobility of0.74cm2/Vs, threshold voltage of-13.45, on/off ratio of1.78x102. Moreover, the electric characteristics of IGZO-TFTs are further improved, with mobility of0.94cm2/Vs, threshold voltage of-13.43, on/off ratio of2.19x102.