On the sputtered particle density and flux evolutions in multi-pulse HiPIMS processes

Abstract The neutral and ionized particles’ density as well as their fluxes are investigated in a multi-pulse high-power impulse magnetron sputtering discharge using atomic absorption spectroscopy combined with a biasable quartz crystal microbalance. As the number of micropulses in the burst increases, a noticeable decrease in the mean discharge current is observed, leading to a reduction in both the ion density and the metal flux fractions. Extending the delay between micropulses results in an increased ionized density fraction, while the ionized metal flux fraction (IMFF) remains largely unchanged. Notably, the deposition rate surpasses that of a conventional direct current magnetron sputtering discharge at the same average power input, even when the IMFF is maintained at approximately 20%. The deposition rate enhancement becomes significant as the micropulse duration surpasses ≈ 130 µ s or a burst containing more than eight micropulses is used.