The effect of negative ions from the target on thin film deposition in a direct current magnetron sputtering system

The effect of the negative oxygen ions in direct current magnetron sputtering on the thin film deposition is investigated with a two-dimensional particle-in-cell simulation with the variation of argon gas pressure ranging from 1.33 to 6.67Pa (10 to 50mTorr). While the plasma density increases with the increase of gas pressure, the total amount of the negative oxygen ions emitted from the target surface does not change significantly with respect to the gas pressure. The amount of high energy O− ions having small incident angles on the substrate decreases with increasing gas pressure especially at the target erosion region. On the contrary, the amount of low energy O− ions having large incident angles on the substrate increases with increasing gas pressure especially at the center region. The tendency for the change of spatial resistivity of ZnO thin films with respect to gas pressure can be explained with the simulation results. •The damage by O− ions on the substrate is analyzed using a particle-in-cell simulation.•With increasing gas pressure, the total amount of O− ions on the substrate decreases.•The amount of high energy O− with small angles decreases with increasing pressure.•The amount of low energy O− with large angles increases with increasing pressure.