Design of rotational RF magnetron sputtering plasma and its characteristics for target utilization saving resources

Good target utilization to save resources in magnetron sputtering is one of the sustainable development goals (SDGs). Rotating cylindrical targets were developed in 1986 [1], while in 2006 rotating unbalanced and asymmetrical magnet arrangements have also been proposed for uniform erosion of the disk target [2]. These magnetron systems have a target utilization rate higher than 80 %. However, they suffer from high costs of the cylindrical target and the rotation shaft can break easily because the center of gravity is not located at the center of the yoke.

In this work, various RF rotational magnetron plasmas, of which some small-magnetron-plasmas are symmetrically arranged on the target disk, have been proposed to improve the target utilization under a center of gravity positioned at the yoke center. The maximum target utilization rate is attained to be higher than 80 %. A design for the RF rotational magnetron plasma is proposed as follows: (a) the small-magnetron-plasma form is selected not to be circular but to correspond to a race-track that widens the target utilization. (b) Various magnet arrangements are used to distribute some small-magnetron-plasmas at rotational symmetry. (c) The rectangular magnet for the small-magnetron-plasma is chosen with considering the diameter of the iron yoke mounted. (d) The magnetic field around the magnets is simulated by a 2D or 3D electromagnetic simulator. (e) The Hall parameter and Larmor radius of electrons are estimated to investigate the electron magnetic confinement in the small-magnetron-plasma. The ion saturation current and the target erosion depth in the proposed rotational RF magnetron plasma are measured to evaluate its characteristics by a Langmuir probe and surface analyzer, respectively.



[1]EP Patent : No.2553137B1, J. T. Gudmundsson, Plasma Sources Sci. Technol. 29 (2020)113001.

[2]T. Iseki, Vacuum, 80(2006)662.