Pulse management in high power pulsed magnetron sputtering of niobium

High power pulsed magnetron sputtering is being intensively explored as a very promising approach for the fabrication of functional coatings with enhanced performance. However, a direct comparison of the results obtained in different systems is complicated given the variety of pulse power supplies with different pulse shape, voltage and current characteristics. In this study, we systematically investigate and compare sputtering processes above a niobium target operated in the same reactor using two commercially available power supplies: (i) a shorter (200 μs) square voltage pulse generator permitting higher cathode voltage values, and (ii) a modulated pulse power generator with longer (800–300 μs) custom-shaped pulses. In addition, target sputtering using a conventional DC power supply is also analyzed for comparison purposes. The pulsed discharges are characterized by time-resolved current and voltage probes and optical emission spectroscopy. The deposition rate, the microstructure, and the mechanical stress of the fabricated Nb coatings are evaluated and compared. Finally, the effect of the power delivery management is discussed in terms of discharge characteristics and coating properties.