Preparation of high quality ITO films on a plastic substrate using RF magnetron sputtering

Indium tin oxide (ITO) thin films were prepared on a plastic substrate (PMMA) by RF magnetron sputtering. A novel deposition system where the plasma deposition region and the resistive heating region are separated in space to minimize the thermal damage to the polymer substrate was utilized. The effects of intentional heating and oxygen addition on microstructure and electrical transport properties of ITO films were investigated. Conductivity of ITO films was found to be strongly dependent on their crystallinity. High conductive (sheet resistance ∼ 19 Ω/sq) and transparent (above 85%) ITO thin films (150 nm) could be obtained with a moderate heating of substrate (about 70 °C) and without introduction of oxygen gas during the deposition. It was observed that amorphous layer with thickness of ∼ 80 nm was formed at the interface on the polymer substrate and polycrystalline ITO was deposited above this thickness. Dependence of the electrical resistivity of ITO films on their thickness was also discussed.