Particle-in-cell Monte Carlo analysis of anomalous target erosion in magnetron sputtering

A parallel computing plasma simulation environment has been implemented at Fraunhofer IST based on the Particle-in-Cell Monte Carlo hybrid approach. Using massiv parallelization 3d3v simulations of low temperature magnetron discharges could be performed within reasonable time. Comparisons with depth profile measurements of eroded magnetron targets and high speed photography of dual magnetron discharges have shown the reliability of the simulation results. Spatial discharge simulations with varying magnetron layouts have been analyzed for the cause of anomalous targets erosin in magnetron sputtering. The simluation showed that the plasma is confind where the magnetic field component perpendicular to the target surface is weakest. This region is referred to as confinement in our work. We found out that two kinds of confinement variations could cause plasma density aggregations in electron drift direction. The subsequent inhomogeneous ion bombardment yields the anomalous target erosion which limits the target material utilization. We state that most of the magnetron related erosion anomalies could be referred to these confinement variations in electron drift direction. According to our thesis we derived two mechanisms for anomalous target erosion in our magnetron sputtering simulation. Both mechanisms have been validated on a simulation basis as well as by experimental measurements.