Characterisation parameters for unbalanced magnetron sputtering systems

Abstract Low pressure sputtering with controlled ratio of ion flux to deposited atom flux at the condensing surface is one of the main directions of development of magnetron sputtering methods. In this paper comparative analysis of three configurations of the magnetron sputtering system has been made. The following parameters, which serve as criteria for the estimation of unbalanced magnetron parameters have been developed: the unbalance coefficient ( K ) and the coefficient of geometrical unbalance ( K G ), which characterise the field configuration at the front of a target. These parameters can be determined by numerical simulation of the magnetic field distribution and the relation between them is characterised by arranging magnetron parameters. Their dependence on the distribution of ion current drawn at the substrate is determined which, taking into account distribution of deposited material, allows calculation of the ion-to-atom ratio on the surface of the condensing material and its dependence on the level of magnetron unbalance. It was determined that the unbalance coefficient K was almost proportionally related to the ion-to-atom ratio for various magnetron types with the same sputtering zone. Also, comparative analysis of three of the magnetron configurations carried out showed that a magnetron with an additional electromagnetic coil is most suitable for low pressure sputtering. Decrease of working pressure down to 0.03 Pa allowed the use of a closed-field configuration of magnetron with an independent ion source of the closed-drift type.