Efficient process control and monitoring for HIPIMS applied to deposition of ITO films

High power impulse magnetron sputtering (HIPIMS) is ideal for deposition of high-quality films from plasmas with high content of ionized sputtered species. For the fabrication of indium tin oxide (ITO) films, a ceramic target is typically used. However, ceramic targets are expensive, provide low deposition rates, and are a source of energetic negative oxygen ions, which cause damage and degradation of film properties. Since HIPIMS makes use of high voltage pulses, problems due to energetic negative ions is a concern. A reactive process using metallic targets will reduce the amount and energy of negative oxygen ions. For a reactive HIPIMS process on lab scale, numerous advantages like better coverage of complex-shaped surfaces, higher deposition rate compared to non-reactive mode, room temperature deposition, decreased lateral resistivity, and decreased surface roughness are reported. Nevertheless, upscaling the process to industrial scale still needs a reliable control of the oxygen flow over large-area rotatable targets. In this work, a room-temperature reactive HIPIMS process for deposition of ITO from a 0.6-m-long rotatable target was investigated. A suitable optical emission control was developed. A comparison between films deposited from ceramic and metallic targets was performed in terms of deposition rate and electrical properties.