The erosion groove effects on RF planar magnetron sputtering

Magnetron sputtering erodes the target non-uniformly, leading to the formation of a circular deep trench called groove, which will have a direct effect on plasma and thin film deposition properties. These effects are highlighted by measurements of the electrical parameters and the deposition rate. Moreover, the measurements of the discharge electrical equivalent plasma impedance indicate clearly, that the occurrence of the target erosion effects is related to the ion sheath thickness formed in front of the eroded target groove. The effects of the eroded target, on discharge parameters, appear from a certain pressure transition range (0.1-0.5 Pa). The eroded target lowers the self-bias voltage by 50%, reduces the deposition rate by almost 40% and increases the ion current density at the substrate. The use of an eroded target improves the plasma confinement, and the electrical equivalent impedance becomes less capacitive and more resistive. Our results show that measuring the plasma impedance might be used as a tool for monitoring the groove formation.