Paper TF+AS+EM+NS+SS-ThM9
Magnetron Deposition of IGZO Thin Films Utilizing dc, Pulsed dc and Bipolar Power Supply

Thursday, October 31, 2013, 10:40 am, Room 104 A

Transparent semiconducting amorphous indium gallium zinc oxide (IGZO) films have attracted great attention due to their excellent electrical properties and possible utilization in thin film transistors or in photovoltaic applications. It is known that the properties of IGZO films prepared by magnetron sputtering are highly sensitive to process parameters, especially to oxygen partial pressure. In this study we have focused on the comparison of various types of power supplies with precise control of process parameters in order to optimize electrical and optical properties of the IGZO thin films. We employed dc and pulsed dc power supplies for single magnetron sputtering and bipolar and mid frequency sine wave power supplies for dual magnetron sputtering. All power supplies were equipped with advanced process stabilization solutions, ultra-fast arc management characterized by very low stored energy, and a digital control platform enabling highly flexible software algorithms design. Magnetrons were equipped either with ceramic InGaZnO targets or with metallic InGaZn targets. A novel fast process control system was used in order to precisely control deposition conditions during reactive magnetron sputtering of IGZO films from metallic targets. It is shown that the electrical resistivity can be effectively controlled in the wide range from 10^-3 to 10⁵ Ω.cm and the field effect mobility can reach values up to 40 cm²/V.s at a film thickness of 270 nm. In parallel to the difference between individual power supplies (sputtering techniques), the effect of the discharge power and the oxygen partial pressure on deposition rate, optical and electrical properties and film structure will be discussed in detail.