Simulation of plasma properties in magnetron sputtering for two kinds of cathode targets

Abstract

During magnetron sputtering process, the common structure of cathode target is planar target and cylindrical rotating target. In this study, cylindrical rotating target is used and two kinds of cathode targets were investigated by COMSOL Multiphysics software (The official network of COMSOL Multiphysics software. https://uk.comsol.com/). We will elucidate the difference between the two types of cathode target and determine the type of cathode target used in the final experiment. We explore the plasma distribution in the radio frequency cavity, so the simulation process was divided into two steps: building RF cavity model and setting up plasma discharge parameters. The main part of the model included the radio frequency cavity substrate (divided into two tube parts and middle ellipsoid part), the cathode and the magnet. And the plasma discharge parameters are as follows: Ar gas was used with 1.5 Pa; magnetic field strength of iron core was set to 1000 Gs; the applied voltage of cathode was set to − 160 V; and anode was set to 0 V. For the long cathode target and the short cathode target, the main difference is the electric field distribution. Because the electric field lines are denser for the long cathode target, the electric field intensity is stronger, and then the initial energy obtained by electrons is higher. During the plasma discharge process, because of the high electron energy, the plasma density produced is more than the simulation of the short cathode target. And under the same simulation time, the residual energy of electrons is more for the long cathode target, which is the reason for the higher electron temperature. From the previous experimental experience, we know that the film quality formed by higher electron energy is better. The simulation in this work shows that the electron energy corresponding to the long cathode target is higher than that of the short cathode target, so we choose the long cathode target as the experimental target in the subsequent coating experiments.