A.W. Oniszczuk1‚ D.A.L. Loch2, A. A. Sugumaran3, W. Gajewski1, K. Markowski1, W. Trzewiczyński1, A.P. Ehiasarian3
1TRUMPF Huettinger Sp. z o.o., Zielonka, Poland
2TRUMPF Hüttinger GmbH + Co. KG, Freiburg, Germany
3Sheffield Hallam University., Sheffield, UK
The study concentrates on the temporal behavior of a HIPIMS discharge with active current control within the pulse duration.
Experiments have been carried out on an AlSi target (600×200 mm) in argon atmosphere. Plasma ignition was performed by applying high power impulses of 8 kW average with voltages up to 1800 V and peak currents up to 600 A. For all tests the average power was held constant by adapting the pulse frequency.
Time resolved optical emission spectral lines were used to monitor gas (Ar I, Ar II) and metal (Al I, Al II, Si I, Si II) species. The HIPIMS discharge evolved through two phases: (1) gas region and (2) metal region, similar to the case of voltage-driven HIPIMS discharge.
The effect of parameters on the temporal evolution of spectral lines intensities was also investigated. The profile of the ionization wave noticeably changed with the change of pulse frequency. In long pulses and off times there was a significant delay in the evolution of Si I and II emission compared to Al due to the differences in sputtering yield. At higher frequencies and shorter off-times, ionization of the metal species occurs faster without delay with respect to the gas. The spectral lines of excited species developed in phase with each other for the whole period. This can be explained with higher density of residual plasma, which aids ignition of the following HIPIMS pulse.