Invited Paper SE+PS-TuA3
Reactive High-power Impulse Magnetron Sputtering and Pulsed Magnetron Co-sputtering of Multifunctional Films

Tuesday, October 20, 2015, 3:00 pm, Room 212A

In the presentation, we report on discharge and deposition characteristics (including the ion flux characteristics at the substrate), and on film structure and properties for two different pulsed reactive magnetron sputtering techniques.

High-power impulse magnetron sputtering (HiPIMS) with a pulsed reactive gas flow control was used for high-rate reactive depositions of densified, highly optically transparent, stoichiometric ZrO­₂ and HfO₂ films, and of Ta-O-N films with tunable composition and properties. The depositions were performed using a strongly unbalanced magnetron with a planar directly water-cooled Zr, Hf or Ta target in Ar-O­₂ or Ar-O₂-N₂ gas mixtures at an average target power density of up to 2.4 kWcm^-2 in a pulse. The repetition frequency of pulses was 500 Hz at 50 – 200 µs voltage pulse lengths and the total pressure close to 2 Pa. An effective reactive gas flow control made it possible to produce high-quality ZrO₂, HfO₂ and Ta-O-N films with high deposition rates (up to 120 nm/min, 345 nm/min and 190 nm/min, respectively, for the target-to-substrate distance of 100 mm) and to adjust the composition of the Ta-O-N films from Ta­₂O₅ to a mixture of Ta₃N₅ and TaN. We prepared almost stoichiometric TaON films possessing appropriate band-edge levels for water splitting and a narrow optical band gap of 2.5 eV that permits a visible light absorption up to 500 nm. Selected results obtained using a parametric model for the controlled reactive HiPIMS of the ZrO₂ films are presented.

Pulsed dc magnetron co-sputtering of a single segmented target (B­₄C-M, where M = Ti, Zr and Hf, or B₄C-Hf-Si) in Ar gas or Ar-N­₂ gas mixtures was used for deposition of different multifunctional films. The repetition frequency of pulses was 10 kHz at a fixed 85 µs voltage pulse length and the total pressure of 0.5 – 1.7 Pa. Energy-resolved mass spectroscopy was used to correlate the energy of Ar⁺ ions bombarding the growing films with high positive voltage overshoots after the negative voltage pulses and with the energy of Ar atoms backscattered from the sputtered targets. We present the results obtained for nanocolumnar ZrB₂-type Zr-B-C films and nanocomposite Zr-B-C-N films exhibiting a high hardness (37 GPa) and high electrical conductivity, and for nanostructured HfB₂-type Hf‑B‑Si‑C films with a high hardness (34 – 37 GPa), high electrical conductivity and significantly improved oxidation resistance in air up to 800 °C.