Ion fluxes in medium frequency pulsed DC magnetron sputtering

The ion fluxes which bombard the substrate during deposition by asymmetric medium frequency pulsed DC magnetron sputtering have been measured as a function of substrate position and pulse frequency. It has been found that, particularly at higher pulse frequencies, the ion flux is dominated by very high energy fluxes which are determined by the positive overshoot voltage in the pulse off period. The behaviour of the ion fluxes on the magnetron centre line and in an offset position has been compared and it is shown that on the centre line there is an additional mid energy ion flux which is not present in the offset position and is thought to arise from the ion flow directed along the magnetic field lines from the racetrack region to the substrate or probe position because of the unbalanced magnetron configuration.