Effects of Working Pressure on the Physical Properties of a-InGaZnO x Films Formed Using Inductively Coupled Plasma-Enhanced Reactive Sputtering Deposition

The effects of working pressure on the physical properties of amorphous InGaZnO x (a-IGZO) films fabricated using inductively coupled plasma-enhanced reactive sputtering deposition were studied, while also assessing the plasma employed during film deposition. With decreasing working pressure, the ion saturation current corresponding to the plasma density increased along with the film deposition rate, because of the greater number of ions incident on the IGZO target. The physical properties of the resulting a-IGZO films were examined to determine the effect of ion energy while varying the working pressure. With decreasing working pressure, the film densities estimated from X-ray reflection data were found to increase. In addition, the concentrations of excess oxygen and hydrogen species incorporated into the a-IGZO films, which can potentially lead to structural and electrical instability, decreased. These results indicate the feasibility of enhancing the electrical properties of a-IGZO films.