On the macroparticle flux from vacuum arc cathode spots

The plasma in vacuum arc cathode spots is always accompanied by a production of metallic macroparticles of size 0.1-10 micrometers. We have studied the macroparticle contamination of vacuum arc deposited thin films generated by a plasma source with an optional axial magnetic field, and have concentrated our attention on the macroparticle flux near the discharge axis. We have varied the arc current, metal species, deposition system geometry and axial magnetic field strength. Distribution functions for macroparticles of Pb, Ag, Cu, Pt, W, and Ni have been determined, normalized to the film thickness deposited or the charge transferred. Application of the axial magnetic field led to a considerable reduction of the normalized macroparticle flux since the plasma was effectively focused by the field whereas the macroparticle production was not influenced. The macroparticle content normalized to the deposited film thickness was reduced to about 20-35% of that without additional magnetic field.