An Optical Emission Spectroscopic Study of Deep Oscillation Magnetron Sputtering of Titanium*

Optical emission spectroscopy was investigated for sputtering plasma generated in deep oscillation magnetron sputtering (DOMS) of titanium in Ar gas in the present study. Temporal profiles of optical emissions of both gas particles and sputtered metal particles in DOMS plasma were observed at a distance in the range of 14 ? 74 mm downstream from the target surface. Almost the same temporal profiles of a given species were obtained for the emission lines which correspond to transitions to metastable and ground levels. On the other hand, the temporal profile was strongly dependent on the species, that is, the metal ion particles and the neutral particles. The peak intensity for the first discharge pulse at the distance of 14 mm was observed to be about 6 times higher for Ti⁺ than for neutral Ti. However, the Ti⁺ intensity for the first discharge pulse more rapidly decreases with increasing distance from the target compared with that of neutral Ti. In addition, the Ti⁺ intensity decreases almost at a distance of the edge of the magnetic trap from the target. Therefore, the present results suggest that the ions were confined in negative plasma potential formed by electron trapping in the strong magnetic field near the target.