Electrical Properties of Ultrathin Indium Tin Oxide Films in Relation to Sputtering Voltage-Current

An ultrathin indium tin oxide (ITO) film (20 +/- 2 nm) was prepared by DC magnetron sputtering. In this study, the electrical properties were improved by optimizing the initial thin film growth process by determining the optimal cathode magnetic field strengths (CMFSs) (0.055, 0.085, and 0.145 T). The optimal deposition conditions for each CMFS to obtain the lowest sheet resistance (R-s) were determined. The conductivity of the ITO thin films grown at room temperature was highest at 0.145 T, intermediate at 0.055 T, and lowest at 0.085 T. However, the effect of post-annealing was different depending on the CMFS, even under identical post-annealing conditions. The electrical properties at 0.085 T improved after post-annealing. The surface morphology improved, and the contact angle increased with a low sputtering voltage (V-s). This is due to a reduction in the damage to the growing film. Improved thin film properties can be achieved by reducing high-energy particle (Ar-0, O-) bombardment and by increasing the number of sputtered atoms with the appropriate energy. Hence, V-s and the sputtering current (I-s), both of which influence the thin film properties, must be adjusted during sputtering.