Optical emission spectroscopy during the deposition of zirconium dioxide films by controlled reactive high-power impulse magnetron sputtering

Time-resolved optical emission spectroscopy was performed near the sputtered Zr target and in a plasma bulk during a controlled high-rate reactive high-power impulse magnetron sputtering of stoichiometric ZrO₂ films in argon-oxygen gas mixtures at the argon pressure of 2 Pa. The repetition frequency was 500 Hz at the deposition-averaged target power density of 52 W cm⁻² with a peak target power density of 1100 W cm⁻². The voltage pulse duration was 200 μs. From the time evolutions of the excited-state populations for the chosen atoms (Zr, Ar, and O) and ions (Zr⁺, Zr²⁺, Ar⁺, and O⁺), and of the excitation temperature during a voltage pulse, the trends in a time evolution of the local ground-state densities of these atoms and ions during the voltage pulse were derived. Near the target, a decrease in the ground-state densities of Ar and O atoms, caused by a gas rarefaction and intense electron-impact ionization, was observed in the first half of the voltage pulse. Simultaneous, very effective electron-impact ionization of sputtered Zr atoms was proved. A composition of particle fluxes onto the substrate during a film deposition was found almost independent of the instantaneous oscillating oxygen partial pressure.