Current-voltage characteristic of magnetron sputtering discharges via particle-in-cell simulations

We explore the current-voltage (IV) characteristic in 2D particle-in-cell (PIC) simulations of direct-current magnetron sputtering (DCMS). DCMS is widely used to sputter-coat thin films, and the IV characteristic is essential for device engineering and optimizing operation. The DCMS IV characteristic is poorly understood and simple models struggle to fit experimental results or do so only in restrictive regimes. Predicting the IV dependence is difficult because of the many interacting processes occurring in the discharge, including target sputtering, electron recapture, and anomalous electron transport. These processes can be modelled by first principles PIC simulations. However, traditional PIC simulations are computationally slow due to the multiscale nature of DCMS. To speed up simulations, we use enhanced PIC techniques such as speed-limited particle-in-cell (SLPIC), an algorithm that enables larger timesteps. We obtain an IV curve with a series of PIC simulations run to steady-state. The results are compared with experimental data.