System design for high rate deposition of indium oxide solar coatings

Indium oxide solar coatings have been extensively investigated and the conditions for their small scale production well characterized. For widespread use of these solar coatings they must be produced at high rate over large areas. Reactive magnetron sputtering is a suitable process and problems in extending this process to larger areas and higher rates are discussed. This is illustrated by results from a 0.5 m wide coater. In a typical commercial coater the process is unstable and so process control by plasma emission monitoring (PEM) is required to give a stable deposition process. To get good film uniformity the gas must be distributed by a gas manifold and there is some interplay between the gas manifold and the PEM control. Experimental results are given to adjust the manifold design for optimum control. On a small scale coater with inherent stability we have achieved a deposition rate of 8 nm/s for indium oxide (with a resistivity of 4 x 10-6 ohm.m). In a larger unstable coater with PEM control we have produced deposition rates of 6 nm/s with a slightly degraded resistivity of 6 x 10-6 ohm.m