Sputter etching of steel substrates using DC and MF pulsed magnetron discharges

For many high rate PVD processes an adequate pre-treatment is necessary immediately before the deposition. Because the high deposition rate of some PVD techniques (e. g. electron beam (EB) evaporation) enable a very high throughput, the pre-treatment must be carried out with an adequate speed. The sputter etching in a magnetron discharge where the substrate serves as a cathode (target) seems to be a very promising pre-treatment technique for this purpose. This technique is especially suitable for flat, electrically conducting substrates like metal strips and sheets. Because of arc problems in direct current (DC) magnetron discharges due to insulating layers on the cathode surface experiments were carried out using discharges in the medium frequency (MF) range (10...100 kHz). During the magnetron sputter etching the light emitted by the etching plasma was investigated by optical emission spectroscopy (OES). After the magnetron sputter etching the substrate surface was investigated by optical glow discharge emission spectroscopy (GDOES). Using a MF pulsed magnetron discharge for sputter etching the damage caused by cathode arcs on the substrate surface could be significantly diminished. However, the MF sputter etching process needs nearly twice as much energy as the DC process to remove a contamination layer from the substrate surface