Characterization of indium tin oxide and al-doped Zinc oxide thin films deposited by confocal RF magnetron sputter deposition

Thin film properties (resistivity, sheet resistance, optical transmissivity, stability testing under RH85/85C conditions and film stress) were measured for indium tin oxide (ITO) and Al-doped Zinc Oxide (ZnO) (2 wt.% Al doped target) films deposited using a confocal RF magnetron sputtering system. A comparison was made between sample biasing and high temperature conditions with respect to these properties. The sample bias was applied by RF power (0 - 60 W) to the sample. For the high temperature runs, the samples were heated to temperatures of as high as 250 C. ITO was deposited with argon as the process gas; Al-ZnO was deposited with a small amount of hydrogen (from 0 to 1%) added to argon. We find that comparable qualities of films can be obtained by either sample biasing or high temperature processes for ITO and Al-ZnO in terms of sheet resistance and transmission. However, sample biasing resulted in significantly higher compressive stress. The sheet resistance of Al-ZnO was affected by addition of hydrogen. The optimal concentration of hydrogen was 0.33% for sample biasing and 0.5% for high temperature runs under the deposition conditions considered.