Target utilization of planar magnetron sputtering using a rotating tilted unbalanced yoke magnet

Abstract

The dependence of the magnetic flux density, erosion uniformity, and target utilization on the yoke magnet tilt angle was investigated in a planar magnetron sputtering system, using a rotating, tilted, unbalanced, asymmetrical magnet. In these experiments, circular and elliptical outer yokes were used as the rotating yoke magnet. The magnetic flux density distributions were measured two-dimensionally on the target surface and compared with the erosion uniformity. As the yoke magnet tilt angle increased, the magnetic flux density distribution expanded and became more uniform, and the eroded areas expanded toward the outside of the target surface. With a circular outer yoke, as the yoke magnet tilt angle increased from 0° to 8°, utilization of a 5-inch target linearly increased from 60 to 80%. On the other hand, with an elliptical outer yoke, the utilization of the target was approximately 70%, regardless of the yoke magnet tilt angle. This is because, as the tilt angle is increased, the inner area of the target eroded more deeply, while the outer area eroded less deeply. The deposition rate when using the elliptical outer yoke was 1.2 times faster than that of when using the circular outer yoke at the same magnet tilt angle. By decreasing the magnetic flux density on the inner area of the target with an elliptical outer yoke magnet, a higher deposition rate may be obtained than is observed with a circular magnet, and target utilization of over 70% can be achieved.