Formation of a Double Circular Erosion Pattern on SiO2 Dielectric Target and Its Effect to Utilization Rate in RF Magnetron Sputtering

Abstract

A circular erosion pattern is formed on the surface of a circular metal conductor target with permanent magnets on its back in rf magnetron sputtering. In this case, the theory behind the erosion pattern has been established. On the other hand, in the case of a dielectric target, a double circular erosion pattern is formed. This pattern is widely known qualitatively and experimentally; however, it has not yet been studied theoretically. In this study, we performed a magnetron sputtering experiment with a SiO2 dielectric target, and were able to confirm the formation of a double circular erosion pattern, which agrees with qualitative theory. Moreover, insulation resistance varied with the thickness of the SiO2 target; thus the dimensions of the double circular erosion pattern varied. Furthermore, we confirmed that a double circular erosion pattern changed by making a gap between the SiO2 target and guard ring. We discussed about utilization rate of the target.