Influence of the external solenoid coil arrangement and excitation mode on plasma characteristics and target utilization in a dc-planar magnetron sputtering system

The influence of external solenoid coil arrangement and excitation mode on plasma characteristics and target utilization was investigated, with an axially external magnetic field $Bext$ being superimposed to the original field of the magnetron source in a dc-planar magnetron sputtering system. The magnetic field configuration was simulated using the finite-element method. Langmuir probe measurement showed that the coil position had a strong effect on the near-substrate plasma parameters, resulting from the variations of magnetic field configuration in the substrate region. Furthermore, it was a relatively simple and effective method to improve the target utilization by supplying a low-frequency ac power to the external coil situated around the magnetron. The target utilization efficiency was highly sensitive to the coil position. The coil was more suitable to be placed in the vicinity of the magnetron for improving the target utilization or near the substrate for increasing the near-substrate plasma density. Finally, a novel method was proposed to simultaneously realize both objects by choosing an appropriate solenoid coil arrangement and excitation mode.