Properties of IGZO Film Deposited by Ar/O2 Inductively Coupled Plasma Assisted DC Magnetron Sputtering

In this study, the effects of inductively coupled plasma (ICP) power added to the DC magnetron sputtering of indium gallium zinc oxide (IGZO) using Ar/O-2 on the plasma characteristics and IGZO thin film characteristics were investigated. The addition of ICP power decreased the magnetron voltage and increased the magnetron current due to the increased plasma density near the magnetron surface. The addition of ICP also increased the deposition rate but also increased the surface roughness of the deposited IGZO thin films. When the electrical characteristics of deposited IGZO thin films were measured, the increase of ICP power to 300 W not only increased the carrier concentration from 1.87 x 10(19) to 2.59 x 10(19) cm(-3) but also increased carrier mobility from 14 to 16.7 cm(2)/Vs possibly due to the decreased defects (decreased defect scattering) in the film even with the increased impurity scattering caused by increased carrier concentration. The further increase of ICP power to 500 W slightly decreased the carrier mobility while slightly increasing the carrier concentration due to both the increased impurity scattering by the increased carrier concentration and the increased surface scattering caused by the increased surface roughness. The optical transmittance was not significantly varied with the ICP power and was higher than 80% at for the visible wavelength and the structure of IGZO deposited at room temperature remained amorphous even with the ICP power up to 500 W.