Ultrathin indium tin oxide (ITO) films 20 nm thickness were manufactured by DC magnetron sputtering for touch sensor applications. Deposition was performed at room temperature on PET substrates, with a substrate-to-target distance of 50 mm, and a power and working pressure of 100 W and 0.28 Pa, respectively. This study focused on improving the electrical properties of ultrathin ITO films, which are typically poor. So, we controlled the initial growth process of the ITO films by optimizing the cathode magnetic field strength (CMFS) (550 G, 850 G, and 1450 G). The electrical properties of the thin films were optimal at the higher CMFS (1450 G) and the surface morphology and wetting properties also improved with strengthening CMFS. This is thought to be the result of a reduction in the damage incurred on the growing film as the plasma impedance and the high-energy particle (ArO, O−) bombardment were reduced. Improved thin film properties can therefore be achieved by reducing high energetic particle (ArO, O−) bombardment and increasing the number of sputter atoms with appropriate energy. In other words, the cathode-voltage (VC) and cathode-current (IC) during sputtering should be carefully adjusted.

Keywords: Ultrathin ITO film, Touch panel, Cathode magnetic field strength, PET, Initial growth mechanism, DC magnetron sputtering.