A study of plasma parameters in a BAI 730 M triode ion plating system by means of a Langmuir probe and plasma mass and energy spectroscopy

The plasma in a physical vapor deposition (PVD) system used for the deposition of hard coatings (TiN, CrN) was studied by means of a Langmuir probe and energy resolved spectroscopy (Balzers plasma process monitor PPM 421). I–V measurements gave the plasma (Upl) and floating (Ufl) potentials, as well as the electron temperature Te and plasma density ni. Upl deduced from I–V measurements agreed well with the peak of the positive ion energy distribution, as well as with the highest positive potential for the given operational mode. Energy spectra measured in deposition of TiN show a high degree of ionization of Ti, with Ti2+ as the prevalent ion. Te calculated from the Maxwellian distribution for the standard deposition of TiN is rather high (Te=6–8 eV). We believe that the oscillations of the plasma potential with the measured amplitude up to 15 V are most probably the reason. The electron energy distribution F(E) is better described by the Druyvesteyn distribution one than by a Maxwellian one.