High Power Pulsed Reactive Sputtering of Zirconium Oxide and Tantalum Oxide

Zirconium oxide and tantalum oxide films were deposited in an inverted cylindrical magnetron cathode using high power pulsed sputtering. Average power densities were between 5 and 7 W/cm2 and peak power densities were in the range of 0.5 kW/cm2. In all of the experiments the oxygen was introduced using flow control, and the current and voltage waveforms of the HPPMS supply changed in a reproducible manner as the targets went from the metallic to the poisoned mode. Coatings were done with the targets in the poisoned mode and for both materials high index films were deposited with very little evidence of arcing. The maximum deposition rate achieved for zirconium oxide was 1.9 nm/min, while tantalum oxide was deposited at 18 nm/min. Comparisons are made with coatings deposited using mid frequency AC sputtering in the same system. The specific deposition rate for zirconium oxide made using the HPPMS power supply was 25% of that when using the AC power supply. In contrast, the specific deposition rates for tantalum oxide were very similar for the two power supplies. X-ray diffraction revealed that the zirconium oxide grew in the monoclinic phase.