High-rate deposition of high-quality Sn-doped In2O3 films by reactive magnetron sputtering using alloy targets

Abstract

Sn-doped In2O3 (ITO) films were deposited on heated (200°C) fused silica glass substrates by reactive DC sputtering with mid-frequency pulsing (50kHz) and a plasma control unit combined with a feedback system of the optical emission intensity for the atomic O* line at 777nm. A planar In–Sn alloy target was connected to the switching unit, which was operated in the unipolar pulse mode. The power density on the target was maintained at 4.4Wcm−2 during deposition. The feedback system precisely controlled the oxidation of the target surface in “the transition region.” The ITO film with lowest resistivity (3.1×10−4Ω cm) was obtained with a deposition rate of 310nmmin−1 and transmittance in the visible region of approximately 80%. The deposition rate was about 6 times higher than that of ITO films deposited by conventional sputtering using an oxide target.